QtPlasmaC

Installation instructions are available at: http://linuxcnc.org/docs/devel/html/getting-started/getting-linuxcnc.html

Following these instructions will yield a machine with the current stable branch (v2.8) of LinuxCNC on Debian Buster.

A package installation (Buildbot) uses prebuilt packages from the LinuxCNC Buildbot, instructions for upgrading from 2.8 to 2.9 are available at: http://buildbot.linuxcnc.org

Following these instructions by using the below stanzas will upgrade the machine to the last LinuxCNC Buildbot build master branch (v2.9) of LinuxCNC. This may not always be the latest version of master branch (v2.9) as from time to time the LinuxCNC Buildbot may stop due to errors.

A run in place installation runs LinuxCNC from a locally compiled version usually located at ~/linuxcnc-dev, instructions for building a run in place installation are available at: http://linuxcnc.org/docs/master/html/code/building-linuxcnc.html

Following these instructions will install the latest master branch (v2.9) of LinuxCNC.

QtPlasmaC requires the selection of one of following three operating modes:

Only one of either Float Switch or Ohmic Probe is required. If both are used then Float Switch will be a fallback if Ohmic Probe is not sensed.

If Ohmic Probe is used then Ohmic Probe Enable is required to be checked on the QtPlasmaC GUI.

Breakaway Switch is not mandatory because the Float Switch is treated the same as a breakaway when not probing. If they are two separate switches, and there are not enough inputs on the breakout board, they could be combined and connected as a Float Switch.

Refer to the Heights Diagram diagram for a visual representation of the terms below.

where: o = overrun, a = acceleration in units/sec2 and v = velocity in units/sec.

Metric example: given a Z axis MAX_ACCELERATION of 600mm/s² and MAX_VELOCITY of 60mm/s, the overrun would be 3mm.

Imperial example: given a Z axis MAX_ACCELERATION of 24in/s² and MAX_VELOCITY of 2.4in/s, the overrun would be 0.12in.

On machines that will utilize an ohmic probe as the primary method of probing, it is highly recommended to install a switch on the floating head as a backup means of stopping Z motion in the event of ohmic probe failure due to dirty surfaces.

LinuxCNC provides two configuration wizards which can be used to build a machine configuration. The choice of these wizards is dependent on the hardware used to control the machine.

If the user wishes to use a Run In Place installation then prior to running one of the following commands they will need to run the following command from a terminal:

If using a Package installation then no additional action is required.

If using a parallel port, use the StepConf wizard (enter the following command into a terminal window):

If using a Mesa Electronics board, use the PnCConf wizard (enter the following command into a terminal window):

If using a Pico Systems board:
This LinuxCNC forum thread may be helpful.

The machine specific settings are not described here, refer to the documentation for the particular configuration wizard that is being used.

There are Linuxcnc forum sections available for these wizards:

StepConf Wizard

PnCConf Wizard

Fill in the required entries to suit the machine wiring/breakout board configuration.

QtPlasmaC adds two pages to the LinuxCNC configuration wizards for QtPlasmaC specific parameters, the two pages are QtPlasmaC options and User Buttons. Complete each of the wizards QtPlasmaC page to suit the machine that is being configured and the user button requirements.

Note that PnCConf options allow user selection of Feed Override, Linear Velocity, and Jog Increments whereas in StepConf these are automatically calculated and set.

PnCConf QtPlasmaC Options:

StepConf QtPlasmaC Options:

QtPlasmaC User Buttons:

QtPlasmaC THCAD:

The THCAD screen will only appear if a Plasma Encoder is selected in the card screen.

More information on Mesa THCAD.

When the configuration is complete, the wizard will save a copy of the configuration that may be loaded and edited at a later time, a working QtPlasmaC configuration will be created in the following directory: ~/linuxcnc/configs/<machine_name>

The newly created QtPlasmaC configuration can be run by entering the following command into a terminal window (change "<machine_name>" to the machine name entered into the configuration wizard):

For a package installation (Buildbot):

For a run in place installation:

After running the above command LinuxCNC should be running with the QtPlasmaC GUI visible.

ONLY WHEN this criteria is met should the user proceed with the QtPlasmaC initial setup.

If any Qt dependency errors are encountered while attempting to run the QtPlasmaC configuration, the user may need to run the QtVCP installation script to resolve these issues.

For a package installation (Buildbot) enter the following command in a terminal window:

For a run in place installation enter the following command in a terminal window:

The following heights diagram will help the user visualize the different heights involved in plasma cutting and how they are measured:

Click on the Parameters Tab to view the CONFIGURATION section which shows the user settable parameters. It is necessary to ensure every one of these settings is tailored to the machine.

To set the Z axis DRO relative to the Z axis MINIMUM_LIMIT, the user should perform the following steps. It is important to understand that in QtPlasmaC, touching off the Z axis DRO has no effect on the Z axis position while running a G-Code program. These steps simply allow the user to more easily set the probe height as after performing the steps, the displayed Z axis DRO value will be relative to Z axis MINIMUM_LIMIT.

If the machine is equipped with a float switch then the user will need to set the offset in the CONFIGURATION section of the PARAMETERS tab. This will be done by running a "Probe Test" cycle.

A quick method to move to QtPlasmaC from PlasmaC (loaded on top of either Axis or Gmoccapy) is to use the plasmac2qt conversion program which will attempt to create a new QtPlasmaC configuration from an existing PlasmaC .ini file. This program will convert the user’s parameters, settings, and materials from the previous PlasmaC configuration and create a new QtPlasmaC configuration folder in the ~/linuxcnc/configs folder.

This methods will keep the original PlasmaC config as a backup with _plasmac and a time stamp appended to the directory name.

To run the plasmac2qt conversion program, use the following instructions:

For a package installation (Buildbot) enter the following line in a terminal window:

For a run in place installation enter the following lines in terminal window:

The following screen will be displayed:

Mandatory Settings

Optional Setting

This setting is not required unless the machine has a laser for sheet alignment.

Leave this blank if it is not used/required.

After filling in the appropriate entries, press CONVERT.

This method to move to QtPlasmaC from PlasmaC (loaded on top of either Axis or Gmoccapy) is to use a configuration wizard to create a new configuration. This method then allows changing of the base machine configuration at a later date via the configuration wizard provided that the base ini and base hal files have not been edited.

This method requires that the user take note of all HAL pins used in the existing config so they can be entered into the configuration wizard. Any custom HAL commands will also need to be noted and added manually to either the custom.hal file or the custom_postgui.hal file which will be created by the configuration wizard.

After using the wizard, the user can then run a conversion program (cfg2prefs) to convert the parameters, settings, and materials from the previous PlasmaC configuration to the new QtPlasmaC configuration. This tool should be used immediately after the user has created a new QtPlasmaC configuration.

Prior to running this conversion program, it is mandatory that the user have both an existing PlasmaC configuration and a new QtPlasmaC configuration. This program WILL overwrite the existing QtPlasmaC preferences and materials files, and should be used with caution if it is not being run on a new QtPlasmaC configuration.

The program will create a time stamped backup of the original preferences file and the existing materials file (if it exists).

It will read the existing <machine_name>_config.cfg, <machine_name>_run.cfg, <machine_name>_wizards.cfg, and plasmac_stats.var files and write them to an existing qtplasmac.prefs file. It will also copy the <machine_name>_material.cfg file to the existing QtPlasmaC configuration.

To run the cfg2prefs conversion program, use the following instructions:

For a package installation (Buildbot) enter the following line in a terminal window:

For a run in place installation enter the following lines in terminal window:

Select the .ini file of the old PlasmaC configuration, select the .ini file of the new QtPlasmaC configuration, then press CONVERT.

The plasmac HAL component has a built in lowpass filter that if used is applied to the plasmac.arc-voltage-in input pin to filter any noise that could cause erroneous voltage readings. The lowpass filter should only be used after using Halscope to determine the required frequency and whether the amplitude of the noise is large enough to cause any issues. For most plasma machines lowpass is not required and should not be used unless it is required.

The HAL pin assigned to this filter is plasmac.lowpass-frequency and is set to 0 (disabled) by default. To apply a lowpass filter to the arc-voltage, the user would edit the following entry in the custom.hal file in the machine’s configuration directory to add the appropriate cutoff frequency as measured in Hertz (Hz).

For example:

The above example would give a cutoff frequency of 100Hz.

Contact bounce from mechanical relays, switches, or external interference may cause some inconsistent behavior of the following switches:

Due to the fact that the software is capable of sampling rates faster than the contact bounce period, it is possible that the software may see contact bounce as several changes in input states occurring in a very small time period, and incorrectly interpret this as a very quick on-off of the input. One method of mitigating contact bounce is to "debounce" the input. To summarize debounce, it requires the input state to be stable at the opposite state of the output state for consecutive delay periods before changing the state of the output.

Debounce delay periods can be changed by editing the appropriate debounce value in the custom.hal file in the <machine_name> config folder.

Each increment of delay adds one servo thread cycle to the debounce time. For example: given a servo thread period of 1000000 (measured in nano seconds), a debounce delay of 5 would equate to 5000000ns, or 5ms.

For the Float and Ohmic switches this equates to a 0.001mm (0.00004") increase in the probed height result.

It is recommended to keep the debounce values as low as possible while still achieving consistent results. Using Halscope to plot the inputs is a good way to establish the correct value.

For QtPlasmaC installations, debounce is achieved by using the HAL dbounce component which is a later alternative to the original debounce component. This new version allows for the loading and naming of individual debounce instances and is compatible with Twopass HAL file processing.

All four signals above have an individual debounce component so the debounce periods can be catered individually to each input. Any changes made to these values in the custom.hal file will not be overwritten by later updates of QtPlasmaC.

The default delay for all four inputs is five servo thread periods. In most cases this value will work quite well. If any of the inputs do not use mechanical switches, it may be possible to either reduce or remove the delay for those inputs.

If debounce is required for other equipment like home or limit switches etc. then more dbounce components may added in any of the HAL files without any regard to the signals listed here.

More information on contact bounce can be seen on page IX of Finder Relays General Technical Information

Mechanical relays and switches usually require a minimum current passing through the contacts for reliable operation. This current varies with the material that the contacts in the device are made from.

Depending on the specified minimum contact current and the current drawn by the input device there may be a need to provide a method to increase the current through the contacts.

Most relays using gold contacts will not require any additional current for reliable operation.

There are two different methods available to provide this minimum current if it is required:

Schematics are shown at contact load schematics.

More information on contact switching load can be seen on page III of Finder Relays General Technical Information

Calculations:

If using a Mesa card, the input resistance could be 5000Ω (7i96) or 10000Ω (7i76E), giving a contact current of 4.8mA or 2.4mA assuming a supply voltage of 24V (I = V/R).

As an example, the typical relay used in a Hypertherm Powermax 65 plasma cutter (TE T77S1D10-24) requires a minimum contact load of 100mA @ 5VDC which will dissipate 0.5W (P = I * V). If using a 24VDC power supply this would then equate to a minimum current of 20.8mA. Because there is less current drawn by the Mesa input than is required by the relay there needs to be an increase in the current.

The resistance can be calculated using R = Vs / (Im - Ii) where:

Using a 7i76E with an input current of 2.4mA gives a calculated value of 1304Ω. (24 / (.0208 - .0024) This could then be rounded down to a commonly available 1200Ω resistor giving a small safety margin.

The power dissipation can by calculated using P = Vs² / Rs where:

This gives a value of 0.48W. This could then be rounded up to 1W, giving a good safety margin. The final selection would be a 1200Ω 1W resistor. Note that this resistor could be used on either the 7i96 or the 7i76E.

If a link to the launch the configuration was not created when creating the config, the user could create a desktop launcher to the config by right clicking on the desktop and selecting Create Launcher or similar. This will bring up a dialog box to create a launcher. Give the icon a nice short name, enter anything for the command and click OK.

After the launcher appears on the desktop, right click on it and then edit it with the user’s editor of choice. Edit the file so it looks similar to:

If the user would like a terminal window to open behind the GUI window then change the Terminal line to:

Displaying a terminal can be handy for error and information messages.

After a successful QtPlasmaC installation, the following files are created in the configuration directory:

After running a new configuration for the first time the following files will be created in the configuration directory:

QtPlasmaC has some specific <machine_name>.ini file variables as follows:

[QTPLASMAC] Section

These variables are optional.

[FILTER] Section

These variables are mandatory.

[RS274NGC] Section

These variables are mandatory.

[HAL] Section

These variables are mandatory.

[DISPLAY] Section

This variable is mandatory.

[TRAJ] Section

This variable is mandatory.

[AXIS_X] Section

These variables are mandatory.

[AXIS_Y] Section

These variables are mandatory.

[AXIS_Z] Section

These variables are mandatory.

Screenshot example of the QtPlasmaC MAIN Tab in 16:9 aspect ratio:

Some functions/features are only used for particular modes and are not displayed if they are not required by the chosen QtPlasmaC mode.

PREVIEW WINDOW

MACHINE

BUTTONS

The Button Panel contains buttons useful for the operation of the machine.

The EDIT and MDI buttons are permanent, all other buttons are user programmable in the <machine_name>.ini file.

See custom user buttons for detailed information on custom user buttons.

ARC

CONTROL

SENSOR

THC

JOGGING

CUT RECOVERY

G-CODE WINDOW

DRO

Screenshot example of the QtPlasmaC CONVERSATIONAL Tab in 16:9 aspect ratio:

The CONVERSATIONAL Tab enables the user to quickly program various simple shapes for quick cutting without the need for CAM software.

See Conversational Shape Library for detailed information on the Conversational feature.

It is possible to disable this tab so the conversational feature cannot be used by an operator. This may be achieved either by wiring the pin to a physical key-switch or similar or it may also be set in a HAL file using the following command:

Screenshot example of the QtPlasmaC PARAMETERS Tab in 16:9 aspect ratio:

Some functions/features are only used for particular modes and are not displayed if they are not required by the chosen QtPlasmaC mode.

Due to space constraints, the 4x3 GUI’s PARAMETERS Tab will be spread across two tabs, PARAMETERS and SETTINGS.

This tab is used to display configuration parameters that are modified infrequently.

It is possible to disable this tab so machine settings cannot be modified by unauthorized personnel. This may be achieved either by wiring the pin to a physical key-switch or similar or it may also be set in a HAL file using the following command:

CONFIGURATION - ARC

CONFIGURATION - PROBING

CONFIGURATION - SAFETY

CONFIGURATION - SCRIBING

CONFIGURATION - SPOTTING

CONFIGURATION - MOTION

CONFIGURATION - THC

SAVE & RELOAD Buttons

The SAVE button will save the currently displayed parameters to the qtplasmac.prefs file.

The RELOAD button will reload all the parameters from the qtplasmac.prefs file.

MATERIAL

This section shows the parameters which are active for the current cut.

SAVE, RELOAD, NEW, & DELETE Buttons

The SAVE button will save the current material set to the <machine_name>_material.cfg file.

The RELOAD button will reload the material set from the <machine_name>_material.cfg file.

The NEW button will allow a new material to be added to the material file. The user will be prompted for a material number and a material name, all other parameters will be read from the currently selected material. Once entered, QtPlasmaC will reload the material file and display the new material. The Cut Parameters for the new material will then need to be adjusted and saved.

The DELETE this button is used to delete a material. After pressing it, the user will be prompted for a material number to be deleted, and prompted again to ensure the user is sure. After deletion, the material file will be reloaded and the drop down list will display the default material.

GUI SETTINGS

This section shows parameters that effect the GUI appearance and GUI behaviors.

To return any of the color changes to their default values, see the Returning To The Default Styling section.

UTILITIES

Some standard LinuxCNC utilities are provided as an aid in the diagnosis of issues that may arise:

In addition the following two QtPlasmaC specific utilities are provided:

The SET OFFSETS button is used if the table has a laser or camera for sheet alignment, a scribe, or uses offset probing. The required offsets for these peripherals need to be applied by following the procedure described in Peripheral Offsets.

The BACKUP CONFIG button will create a complete machine configuration backup for archiving or to aid in fault diagnosis. A compressed backup of the machine configuration will be saved in the user’s Linux home directory. The file name will be <machine_name>_<version>_<date>_<time>.tar.gz where <machine_name> is the machine name entered in the configuration wizard, <version> is the current QtPlasmaC version the user is on, <date> is the current date (YY-MM-DD), and <time> is the current time (HH-MM-SS).

Prior to the backup being made, the machine log will be saved to a file in the configuration directory named machine_log_<date>_<time>.txt where <date> and <time> are as described above. This file along with up to five previous machine logs will also be included in the backup.

These files are not required by QtPlasmaC and are safe to delete at any time.

The STATISTICS Tab provides statistics to allow for the tracking of consumable wear and job run times.

These statistics are shown for the current job as well as the running total.

Previous job statistics are reset once the next program is run.

The total values may be reset either individually by clicking the corresponding "RESET" button, or they may all be reset together by clicking "RESET ALL".

The RS485 PMX STATISTICS panel will be only be displayed if the user has Hypertherm PowerMax communications and a valid RS485 connection to the PowerMax is established. This panel will show the ARC ON TIME for the PowerMax in hh:mm:ss format.

The MACHINE LOG is also displayed on the STATISTICS Tab, this log will display any errors and/or important information that occurs during the current LinuxCNC session. If the user makes a backup of the configuration from the PARAMETERS Tab then the machine log is also included in the backup.

All settings and parameters in QtPlasmaC are required to be in the same units as specified in the ini file, being either metric or imperial.

If the user is attempting to run a G-Code file that is in the "other" units system then all parameters including the material file parameters are still required to be in the native machines units. Any further conversions necessary to run the G-Code file will be handled automatically by the G-Code filter program.

For example: if a user had a metric machine and wished to run a G-Code file that was set up to cut 1/4" thick material using imperial units (inch - G20) then the user with the metric machine would need to ensure that either the material number in the G-Code file was set to the corresponding metric material to be cut, or that a new material is created with the correct metric parameters for the metric material to be cut. If the metric user wanted to cut the G-Code file using imperial material, then the new material parameters would need to be converted from imperial units to metric when they are entered.

The following stanzas are the minimum recommended codes to include in the preamble and postamble of any G-Code file to be run by QtPlasmaC:

Metric:

Imperial:

A detailed explanation of each G-Code can be found in the docs here.

Note that throughout this user guide there are several additional recommendations for codes that are prudent to add to both the preamble and postamble depending on the features the user wishes to utilize.

Aside from the preamble code, postamble code, and X/Y motion code, the only mandatory G-Code syntax for QtPlasmaC to run a G-Code program using a torch for cutting is M3 $0 S1 to begin a cut and M5 $0 to end a cut.

For backwards compatibility it is permissible to use M3 S1 in lieu of M3 $0 S1 to begin a cutting job and M5 in lieu of M5 $0 to end a cutting job. Note that this applies to cutting jobs only, for scribe and spotting jobs the $n tool identifier is mandatory.

See recommended Z axis settings.

Each time LinuxCNC (QtPlasmaC) is started Joint homing is required. This allows LinuxCNC (QtPlasmaC) to establish the known coordinates of each axis and set the soft limits to the values specified in the <machine_name>.ini file in order to prevent the machine from crashing into a hard stop during normal use.

If the machine does not have home switches then the user needs to ensure that all axes are at the home coordinates specified in the <machine_name>.ini file before homing.

If the machine has home switches then it will move to the specified home coordinates when the Joints are homed.

Depending on the machine’s configuration there will either be a Home All button or each axis will need to be homed individually. Use the appropriate button/buttons to home the machine.

As mentioned in the Initial Setup section, it is recommended that the first time QtPlasmaC is used that the user ensure there is nothing below the torch then jog the Z axis down until it stops at the Z axis MINIMUM_LIMIT then click the 0 next to the Z axis DRO to Touch Off with the Z axis selected to set the Z axis at zero offset. This should not need to be done again.

If the user intends to place the material in the exact same place on the table every time, the user could jog the X and Y axes to the machine to the corresponding X0 Y0 position as established by the CAM software and then Touch Off both axes with a zero offset.

If the user intends to place the material randomly on the table then the user must Touch Off the X and Y axes at the appropriate position before starting the program.

QtPlasmaC is able to read a material file to load all the required cut paramaters. To enable to G-Code file to use the cut feed rate setting from the cut parameters use the following code in the G-Code file:

It is possible to use the standard G-Code F word to set the cut feed rate as follows:

If the F word is used and the F word value does not match the cut feed rate of the selected material then a warning dialog will indicate this during loading of the G-Code file.

Material handling uses a material file that was created for the machine configuration when the configuration wizard was ran and allows the user to conveniently store known material settings for easy recall either manually or automatically via G-Code. The resulting material file is named <machine_name>_material.cfg.

QtPlasmaC does not require the use of a material file. Instead, the user could change the cut parameters manually from the MATERIAL section of the PARAMETERS Tab. It is also not required to use the automatic material changes. If the user does not wish to use this feature they can simply omit the material change codes from the G-Code file.

It is also possible to not use the material file and automatically load materials from within the G-Code file.

Material numbers in the materials file do not need to be consecutive nor do they need to be in numerical order.

The following variables are mandatory and an error message will appear if any are not found when the material file is loaded.

The following variables are optional. If they are not detected or have no value assigned, they will be assigned a value of 0 and no error message will appear.

The material file uses the following format:

It is possible to add new material, delete material, or edit existing material from the PARAMETERS tab. It is also possible to achieve this by using magic comments in a g-Code file.

The material file may be edited with a text editor while LinuxCNC is running. After any changes have been saved, press Reload in the MATERIAL section of the PARAMETERS Tab to reload the material file.

For manual material handling, the user would manually select the material from the materials list in the MATERIAL section of the PARAMETERS Tab before starting the G-Code program. In addition to selecting materials with materials list in the MATERIAL section of the PARAMETERS Tab, the user could use the MDI to change materials with the following command:

The following code is the minimum code necessary to have a successful cut using the manual material selection method:

For automatic material handling, the user would add commands to their G-Code file which will enable QtPlasmaC to change the material automatically.

The following codes may be used to allow QtPlasmaC to automatically change materials:

For automatic material handling, the codes MUST be applied in the order shown. If a G-Code program is loaded which contains one or more material change commands then the first material will be displayed in the top header of the PREVIEW WINDOW on the MAIN Tab as the program is loading. The following code is the minimum code necessary to have a successful cut using the automatic material selection method:

By using "magic comments" in a G-Code file it is possible to do the following:

Temporary materials are numbered automatically by QtPlasmaC and the material change will also be done by QtPlasmaC and should not be added to the G-Code file by CAM software or otherwise. The material numbers begin at 1000000 and are incremented for each temporary material. It is not possible to save a temporary material, however the user could create a new material while a temporary material is displayed and it will use the settings from the temporary material as the defaults.

The options are:

Mandatory parameters are:

Optional parameters are:

A complete example:

If a temporary material has been specified in a G-Code file then the material change line (M190…) and wait for change line (M66…) will be added by the G-Code filter and are not required in the G-Code file.

This application is used to convert existing tool tables into QtPlasmaC material files. It can also create a material file from manual user input to entry fields.

At this stage the only conversions available are for tool tables exported from either SheetCam or Fusion 360.

SheetCam tool tables are complete and the conversion is fully automatic. The SheetCam tool file must be in the SheetCam .tools format.

Fusion 360 tool tables do not have all of the required fields so the user will be prompted for missing parameters. The Fusion 360 tool file must be in the Fusion 360 .json format.

If the user has a format from a different CAM software they would like converted, create a New Topic in the PlasmaC forum section of the LinuxCNC forum to request this addition.

Material Converter may be run from a terminal using one of the two following methods.

For a package installation (Buildbot) enter the following command in a terminal window:

For a run in place installation enter the following two commands in a terminal window:

This will bring up the Material Converter Main dialog box with Manual selected as the default.

Select one of:

For SheetCam only, select whether the user requires a metric or imperial output file.

To convert:

For both a Manual creation or a Fusion 360 conversion, a dialog box will show with all available parameters displayed for input. Any entry marked with *** is mandatory and all other entries are optional depending on the user’s configuration needs.

QtPlasmaC has the ability to use a USB camera to set the origin with or without rotation compensation. The CAMERA button will be enabled after the machine is homed.

To use this feature, the user must set the camera’s offset from the torch center by following the procedure described in Peripheral Offsets.

To add or modify the offsets manually, the user could add or edit the following line in the [QTPLASMAC] section:

"offset" is distance from the center line of the torch to the camera’s cross hairs. Offsets could be specified as x25.4, X25.4, or 25.4.

To set the origin with zero rotation:

To set the origin with rotation:

In the CAMVIEW panel, the mouse can affect the cross hairs and the zoom level as follows:

QtPlasmaC has the ability to use a laser to set the origin with or without rotation compensation. The LASER button will be enabled after the machine is homed.

To use this feature, the user must set the laser’s offset from the torch center by following the procedure described in Peripheral Offsets.

To add or modify the offsets manually, the user could add or edit the following line in the [QTPLASMAC] section:

"offset" is distance from the center line of the torch to the camera’s cross hairs. Offsets could be specified as x25.4, X25.4, or 25.4.

Additionally, the laser can be tied to any available output to turn the laser on and off via a HAL pin with the following name:

To set the origin with zero rotation:

To set the origin with rotation:

To turn the laser off and cancel an alignment:

The provided RS274NGC_STARTUP_CODE files: metric_startup.ngc and imperial_startup.ngc set the motion blending path tolerance with a G64 command P value to 0.1mm and 0.004" respectively. The P value corresponds to the amount the actual cut path followed by the machine may deviated from the programmed cut path before reducing velocity. If LinuxCNC (QtPlasmaC) receives an E-stop signal at any stage, the path tolerance will be set to the default (no P value) which will maintain the best possible speed and round corners off as a result. To prevent this, it is recommended that the path tolerance is set by placing the appropriate G64 command and P value in the header of each G-Code file.

For Metric:

For Imperial:

QtPlasmaC has the ability to allow the repositioning of the X and Y axes along the current cut path while the G-Code program is paused.

In order to use this feature, LinuxCNC’s Adaptive Feed Control (M52) must be turned on (P1).

To enable Paused Motion The preamble of the G-Code must contain the following line:

To turn off Paused Motion at any point, use the following command:

This feature can be used to allow the arc to "catch up" to the torch position to fully finish the cut. It is usually required for thicker materials and is especially useful when cutting stainless steel.

Using this feature will cause all motion to pause at the end of the cut while the torch is still on. After the dwell time (in seconds) set by the Pause At End parameter in the MATERIAL section of the PARAMETERS Tab has expired, QtPlasmaC will proceed with the M5 command to turn off and raise the torch.

QtPlasmaC has the ability to allow the use of more than one type of plasma tool by utilizing LinuxCNC spindles as a plasma tool when running a G-Code program.

Valid plasma tools for use are:

A LinuxCNC spindle number (designated by $n) is required to be in the starting command and also the end command to be able to start and stop the correct plasma tool. Examples:

It is permissible to use M5 $-1 in lieu of the M5 $n codes above to stop all tools.

In order to use a scribe, it is necessary for the user to add the X and Y axis offsets to the LinuxCNC tool table. Tool 0 is assigned to the Plasma Torch and Tool 1 is assigned to the scribe. Tools are selected with a Tn M6 command, and then a G43 H0 command is required to apply the offsets for the selected tool. It is important to note that the LinuxCNC tool table and tool commands only come into play if the user is using a scribe in addition to a plasma torch. For more information, see scribe.

There is a HAL pin available named motion.analog-out-03 that can be changed in G-Code with the M67 (Synchronized with Motion)/M68 (Immediate) commands. This pin will reduce the velocity to the percentage specified in the command.

It is important to thoroughly understand the difference between Synchronized with Motion and Immediate:

Examples:

The minimum percentage allowed is 10%, values below this will be set to 10%.

The maximum percentage allowed is 100%, values above this will be set to 100%.

If the user intends to use this feature it would be prudent to add M68 E3 Q0 to both the preamble and postamble of the G-Code program so the machine starts and ends in a known state.

The THC can be enabled or disabled from the THC frame of the MAIN Tab.

The THC can also be enabled or disabled directly from the G-Code program.

The THC does not become active until the velocity reaches 99.9% of the CutFeedRate and then the THC Delay time if any in the THC section of the PARAMETERS Tab has timed out. This is to allow the arc voltage to stabilize.

QtPlasmaC uses a control voltage which is dependent on the state of the AUTO VOLTS checkbox on the MAIN Tab:

G-Code THC

THC may be disabled and enabled directly from G-Code, provided the THC is not disabled in the THC Section of the MAIN Tab, by setting or resetting the motion.digital-out-02 pin with the M-Codes M62-M65:

It is important to thoroughly understand the difference between Synchronized with Motion and Immediate:

Velocity Based THC

If the cut velocity falls below a percentage of CutFeedRate (as defined by the VAD Threshold % value in the THC frame of the CONFIGURATION section of the PARAMETERS Tab) the THC will be locked until the cut velocity returns to at least 99.9% of CutFeedRate. This will be made apparent by the THC Velocity Lock indicator illuminating in the CONTROL Panel on the MAIN Tab.

Velocity based THC prevents the torch height being changed when velocity is reduced for a sharp corner or a small hole.

It is important to note that Velocity Reduction affects the Velocity Based THC in the following ways:

LinuxCNC (QtPlasmaC) has the ability to automatically adjust the cut path of the current program by the amount specified in Kerf Width of the selected material’s Cut Parameters. This is helpful if the G-Code is programmed to the nominal cut path and the user will be running the program on different thickness materials to help ensure consistently sized parts.

To use cutter compensation the user will need to use G41.1, G42.1 and G40 with the kerf width HAL pin:

IHS may be skipped in one of two different ways:

A value of zero for Skip IHS will disable IHS skipping.

Any errors encountered during a cut will disable IHS skipping for the next cut if Skip IHS is enabled.

Probing may be done with either ohmic sensing or a float switch. It is also possible to combine the two methods, in which case the float switch will provide a fallback to ohmic probing. An alternative to ohmic probing is Offset Probing

If the machine’s torch does not support ohmic probing, the user could have a separate probe next to the torch. In this case the user would extend the probe below the torch. The probe must NOT extend more than the minimum Cut Height below the torch and the Z axis offset distance needs to be entered as the Ohmic Offset in the PROBING frame of the CONFIGURATION section of the PARAMETERS Tab.

Probing setup is done in the PROBING frame of the CONFIGURATION section of the PARAMETERS Tab.

QtPlasmaC can probe at the full Z axis velocity so long as the machine has enough movement in the float switch to absorb any overrun. If the machine’s float switch travel is suitable, the user could set the Probe Height to near the Z axis MINIMUM_LIMIT and do all probing at full speed.

Some float switches can exhibit a large switching hysteresis which shows up in the probing sequence as an excessive time to complete the final probe up.

where n is a value from 1-10. It is recommended to keep this value as low as possible.

Using this feature will change the final height slightly and will require thorough probe testing to confirm the final height.

This speed value affects ALL probing so if the user uses ohmic probing and the user changes this speed value then the user will need to probe test to set the require offset to compensate for this speed change as well as the float travel.

The reliability of this feature will only be as good as the repeatability of the float switch.

Offset Probing is the use of a probe that is offset from the torch. This method is an alternative to Ohmic Probing and uses the plasmac.ohmic-enable output pin to operate a solenoid for extending and retracting the probe. The plasmac.ohmic-probe input pin is used to detect the material and the Ohmic Offset in the PROBING frame of the CONFIGURATION section of the PARAMETERS Tab is used to set the correct measured height.

The probe could be a mechanically deployed probe, a permanently mounted proximity sensor or even simply a stiff piece of wire extending about 0.5mm below the torch tip. If the probe is mechanically deployed then it needs to extend/retract rather quickly to avoid excessive probing times and would commonly be pneumatically operated.

To use this feature, the user must set the probes’s offset from the torch center by following the procedure described in Peripheral Offsets.

To add or modify the offsets manually, the user could add or edit the following line in the [QTPLASMAC] section:

where n.n is the offset of the probe from the torch center in machine units for the X and Y axes and t.t is the time in seconds to allow for any mechanical deployment of the probe if required.

Each of these parameters is optional and also may appear in any order. If a parameter is not detected then the default is 0.0. There can be no space after the X or Z, lower case is permissible.

When this variable appears in the INI file with either X or Y not equal to zero then QtPlasmaC will do all Ohmic Probing as Offset Probing. When a probe sequence has begun, the plasmac.ohmic-enable pin will be set True causing the probe to extend. When the material is detected the plasmac.ohmic-enable pin will be reset to false causing the probe to retract.

The probe will begin moving to the offset position simultaneously with the Z axis moving down to the Probe Height, probing will not commence unless the deployment timer has completed. It is required that the Probe Height in the PROBING frame of the CONFIGURATION section of the PARAMETERS Tab is above the top of the material to ensure that the probe is fully offset to the correct X/Y position before the final vertical probe down movement.

QtPlasmaC allows two different cut modes:

Pierce Only mode is useful for thick materials which may produce enough dross on the material surface from piercing to interfere with the torch while cutting. This enables the entire sheet to be pierced and cleaned off before cutting.

This also enables near-end-of-life consumables to be used for piercing and then they can be swapped out for good consumables to be used while cutting.

There are two ways of enabling this feature:

If using a custom user button is utilized then QtPlasmaC will automatically reload the file when the cut type is toggled.

It is recommended that any holes to be cut have a diameter no less than one and a half times the thickness of the material to be cut.

It is also recommended that holes with a diameter of less than 32mm (1.26") are cut at 60% of the feed rate used for profile cuts. This should also lock out THC due to velocity constraints.

QtPlasmaC can utilize G-Code commands usually set by a CAM Post Processor (PP) to aid in hole cutting or if the user does not have a PP or the user’s PP does not support these methods then QtPlasmaC can automatically adapt the G-Code to suit. This automatic mode is disabled by default.

There are three methods available for improving the quality of small holes:

G-Code commands can be set up by either by a CAM Post Processor (PP) or by hand coding.

Hole Cutting Velocity Reduction

If cutting a hole requires a reduced velocity then the user would use the following command to set the velocity: M67 E3 Qnn where nn is the percentage of the velocity desired. For example, M67 E3 Q60 would set the velocity to 60% of the current material’s CutFeedRate.

See the Velocity Based THC section.

Sample code:

Arc Dwell (Pause At End)

This method can be invoked by setting the Pause At End parameter in the MATERIAL frame of the PARAMETERS Tab.

Overcut

The torch can be turned off at the end of the hole by setting the motion.digital-out-03 pin with the M-Codes M62 (Synchronized with Motion) or M64 (Immediate). After turning the torch off it is necessary to allow the torch to be turned on again before beginning the next cut by resetting the motion.digital-out-03 pin with the M-Codes M63 or M65, this will be done automatically by the QtPlasmaC G-Code parser if it reaches an M5 command without seeing a M63 P3 or M65 P3.

After the torch is turned off the hole path will be followed for a default length of 4mm (0.157"). This distance may be specified by adding #<oclength> = n to the G-Code file.

It is important to thoroughly understand the difference between Synchronized with motion and Immediate:

Sample code:

QtPlasmaC has the ability to automatically modify the G-Code to reduce the velocity and/or apply Overcut which can be useful when cutting holes.

For valid hole sensing it is required that all values in the G2 or G3 G-Code line are explicit, an error dialog will be dispalyed if any values are mathematically calculated.

QtPlasmaC Hole Sensing is disabled by default. It can be enabled/disabled by using the following G-Code parameters to select the desired hole sensing mode:

The default hole size for QtPlasmaC hole sensing is 32mm (1.26"). It is possible to change this value with the following command in a G-Code file:

The default velocity for QtPlasmaC small holes is 60% of the current feed rate. It is possible to change this value with the following command in a G-Code file:

Overcut

If Hole Sensing modes 2 or 4 are active, QtPlasmaC will overcut the hole in addition to the velocity changes associated with modes 1 and 3.

The default overcut length for QtPlasmaC hole sensing is 4mm (0.157"). It is possible to change this value with the following command in a G-Code file:

Arc Dwell (Pause At End)

This feature can be used in addition to setting the desired hole sensing mode via the appropriate G-Code parameter by setting the Pause At End parameter in the MATERIAL frame of the PARAMETERS Tab.

Sample code:

A single cut is a single unidirectional cutting move often used to cut a sheet into smaller pieces prior to running a G-Code program.

The machine needs to be homed before commencing a single cut.

A single cut will commence from the machine’s current X/Y position.

Automatic Single Cut

This is the preferred method. The parameters for this method are entered in the following dialog box that is displayed after pressing a user button which has been coded to run single cut:

Pendant Single Cut

If the machine is equipped with a pendant that can start and stop the spindle plus jog the X and Y axes, the user can manually perform a single cut.

Manual Single Cut

Manual single cut requires that either keyboard shortcuts are enabled in the GUI SETTINGS section of the PARAMETERS Tab, or a custom user button is specified as a manual cut button.

If the user is using a custom user button then substitute F9 with User Button in the following description.

QtPlasmaC is capable of cutting of expand (mesh) metal provided the machine has a pilot arc torch and it is capable of Constant Pilot Arc (CPA) mode.

Mesh Mode disables the THC and also ignores a lost Arc OK signal during a cut. It can be selected by checking the Mesh Mode check button in the CONTROL section of the MAIN Tab.

If the machine has RS485 communications enabled with a Hypertherm PowerMax plasma cutter, selecting Mesh Mode will automatically override the Cut Mode for the currently selected material and set it to cut mode 2 (CPA). When Mesh Mode is disabled, the Cut Mode will be return to the default cut mode for the currently selected material.

It is also possible to start a Mesh Mode cut without receiving an Arc OK signal by checking the Ignore Arc OK check button in the CONTROL section of the MAIN Tab.

Both Mesh Mode and Ignore Arc OK can be enabled/disabled at any time during a job.

Ignore Arc OK mode disables the THC, will begin a cut without requiring an Arc OK signal, and will ignore a lost Arc OK signal during a cut.

This mode can be selected by:

It is important to thoroughly understand the difference between Synchronized with motion and Immediate:

This mode may also be used in conjunction with Mesh Mode if the user doesn’t require an Arc OK signal to begin the cut.

Both Mesh Mode and Ignore Arc OK can be enabled/disabled at any time during a job.

This feature will produce a CUT RECOVERY panel that will allow the torch to be moved away from the cut path during a paused motion event in order to position the torch over a scrap portion of the material being cut so that the cut restarts with a minimized arc-divot. The CUT RECOVERY panel will display automatically over top of the JOGGING panel when motion is paused.

It is preferable to make torch position adjustments from the point at which paused motion occurred, however if moving along the cut path is necessary prior to setting the new start point, the user may use the paused motion controls (REV, FWD, and a JOG-SPEED slider) at the top of the CUT RECOVERY panel. Once the user is satisfied with the positioning of the torch along the cut path, moving off the cut path is achieved by pressing the DIRECTION buttons. Each press of the DIRECTION button will move the torch a distance equivalent to the Kerf Width parameter of the currently selected material.

The moment the torch has been moved off the cut path, the paused motion controls (REV, FWD, and a JOG-SPEED slider) at the top of the CUT RECOVERY panel will become disabled.

Once the torch position is satisfactory, press CYCLE RESUME and the cut will resume from the new position and travel the shortest distance to the original paused motion location. The CUT RECOVERY panel will close and the JOGGING panel will display when the torch returns to the original paused motion location.

Pressing CANCEL MOVE (or CYCLE STOP) will cause the torch to move back to where it was positioned when the motion became paused and the CUT RECOVERY panel overlay will return to the JOGGING panel.

If the user has the Run From Line option enabled in the GUI SETTINGS section of the PARAMETERS Tab they will have the ability to start from any line in a G-Code program via the following methods:

Note that the Run From Line function will run from the beginning of the selected line.

It is important to note that G-Code programs can be run from any selected line using this method, however a leadin may not be possible depending on the line selected. In this case, an error message will be displayed to let the user know the leadin calculation was not possible.

Once the user has selected the starting place, the CYCLE START button will blink "SELECTED nn" where nn is the corresponding line number selected. Clicking this button will bring up the following Run From Line dialog box:

After pressing LOAD, the blinking "SELECTED nn" button will change to RUN FROM LINE CYCLE START button. Click this button to start the program from the beginning of the selected line.

Run From Line selections may be canceled in the following ways:

A scribe may be operated by QtPlasmaC in addition to the plasma torch.

Using a scribe requires the use of the LinuxCNC tool table. Tool 0 is assigned to the plasma torch and Tool 1 is assigned to the scribe. The scribe X and Y axes offsets from the plasma torch need to be entered into the LinuxCNC tool table. This is done by editing the tool table via the main GUI, or by editing the tool.tbl file in the <machine_name> configuration directory. This will be done after the scribe can move to the work piece to help determine the appropriate offset.

The plasma torch offsets for X and Y will always be zero. The tools are selected by the Tn M6 command followed by a G43 H0 command which is required to apply the offsets. The tool is then started with a M3 $n S1 command. For n, use 0 for torch cutting or 1 for scribing.

To stop the scribe, use the G-Code command M5 $1.

If the user has not yet assigned the HAL pins for the scribe in the configuration wizard then they may do so by using the appropriate configuration wizard or by manually editing the hal file, see modifying QtPlasmaC.

There are two HAL output pins used to operate the scribe, the first pin is used to arm the scribe which moves the scribe to the surface of the material. After the Arm Delay has elapsed, the second pin is used to start the scribe. After the On Delay has elapsed, motion will begin.

Using QtPlasmaC after enabling the scribe requires the selection of either the torch or the scribe in each G-Code file as a LinuxCNC tool.

The first step is to set the offsets for the scribe by following the procedure described in Peripheral Offsets.

The final step is to set the scribe delays required:

Save the parameters in the Config tab.

After the above directions are completed, the scribe may be tested manually by issuing a M3 $1 S1 command in the MDI input. The user may find it helpful to use this method to scribe a small divot and then try to pulse the torch in the same location to align the offsets between the scribe and the torch.

To use the scribe from G-Code:

It is a good idea to switch back to the torch at the end of the program before the final rapid parking move so the machine is always in the same state at idle.

The user can switch between the torch and the scribe any number of times during a program by using the appropriate G-Codes.

Issuing M3 S1 (without $n) will cause the machine to behave as if an M3 $0 S1 had been issued and issuing M5 (without $n) will cause the machine to behave as if an M5 $0 had been issued. This will control the torch firing by default in order to provide backward compatibility for previous G-Code files.

To achieve spotting to mark the material prior to drilling etc., QtPlasmaC can pulse the torch for a short duration to mark the spot to drill.

Spotting can be configured by following these steps:

The torch is then turned on in G-Code with the M3 $2 S1 command which selects the plasma torch as a spotting tool.

To turn the torch off, use the G-Code command M5 $2.

For more information on multiple tools, see multiple tools.

LinuxCNC (QtPlasmaC) requires some motion between any M3 and M5 commands. For this reason, a minimal movement at a high speed is required to be programmed.

An example G-Code is:

Virtual keyboard support is available for only the "onboard" onscreen keyboard. If it is not already on the system it may be installed by typing the following in a terminal:

The following two custom layouts are used for soft key support:

If the virtual keyboard has been repositioned and on the next opening of a virtual keyboard it is not visible then clicking twice on the onboard icon in the system tray will reposition the virtual keyboard so the move handle is visible.

Below is a list of all available keyboard shortcuts in QtPlasmaC.

In order to utilize them, KB Shortcuts must be enabled in the GUI SETTINGS section of the PARAMETERS Tab.

Global settings for the shape library can be set by pressing the SETTINGS button in the CONVERSATIONAL Tab. This will display all of the available settings parameters that are used for G-Code program creation. These include:

Any internal circle that has a diameter less than Small hole diameter is classified as a small hole and will have a straight lead-in with a length that is the lesser of either the radius of the hole or the specified lead-in length. It will also have its feed rate set to Small hole speed.

Pressing the RELOAD button will discard any changed settings.

Pressing the SAVE button will save all the settings as displayed.

After pressing SAVE or RELOAD, the settings panel will close and the user may press click on any shape to start/resume the Conversational process.

Lines and arcs have an additional option in that they may be strung together to create a complex shape.

There are two line types and three arc types available:

To use lines and arcs:

If the user wishes to create a closed shape, they will need to create any required lead-in as the first segment of the shape. If a lead-out is required it will need to be the last segment of the shape.

The following shapes are available for creation:

To create a shape:

For CIRCLE, the OVERCUT button will become valid when a CUT TYPE of INTERNAL is selected and the value entered in the DIAMETER field is less than the Small Hole Diameter parameter in the Conversational SETTINGS section.

For BOLT CIRCLE the OVERCUT button will become valid if the value entered in the HOLE DIA field is less than the SMALL HOLES DIAMETER parameter in the Conversational SETTINGS section.

For the following shapes, KERF OFFSET will become active once a LEAD IN is specified:

Multiple shapes can be added together to create a complex group.

The cut order of the group is determined by the order in which the individual shapes are added to the group.

Once a shape is added to the group it cannot be edited or removed.

Groups cannot have shapes removed, only added to.

To create a group of shapes:

The Conversational Block feature allows block operations to be performed on the current shape or group of shapes displayed in the CONVERSATIONAL Tab. This can include a G-Code file not created using the Conversational Shape Library that has been previously loaded from the MAIN Tab.

A previously saved Block G-Code file may also be loaded from the MAIN Tab and then have any of its operations edited using the Conversational Block feature.

Block operations:

To create a block:

COLUMNS & ROWS - specifies the number of duplicates of the original shape arranged in columns and rows as well as the offset distance from the original shape.

ORIGIN - offset the result from the origin coordinates.

ANGLE - rotate the result.

SCALE - scale the result.

ROTATION - rotate the shape within the result.

MIRROR - mirror the shape about its X coordinates within the result.

FLIP - flip the shape about its Y coordinates within the result.

If the result is an array of shapes then the cut order of the result is from the left column to the right column, starting at the bottom row and ending at the top row.

The current job displayed in the Preview Panel may be saved at any time by using the bottom SAVE button. If the G-Code has been sent to LinuxCNC (QtPlasmaC) and the user has left the CONVERSATIONAL Tab, the user may still save the G-Code file from the GUI. Alternatively, the user could click the CONVERSATIONAL Tab which will reload the job, at which time they can press the SAVE button.

All errors are logged into the machine log which is able to be viewed in the STATISTICS Tab. The log file is saved into the configuration directory when QtPlasmaC is shutdown. The five last logfiles are kept, after which the oldest logfile is deleted each time a new log file is created. These saved log files may be viewed with any text editor.

By default, QtPlasmaC will display error messages via a Operator Error popup window. In addition, QtPlasmaC will alert the user that an error has been sent to the machine log by displaying the message "ERROR SENT TO MACHINE LOG" in the lower left portion of the status bar.

The user may opt to disable the Operator Error popup window, and view the error messages by going to the STATISTICS Tab by changing the following preference to False in the [SCREEN_OPTIONS] of the qtplasmac.prefs file in the <machine_name> folder:

Additionally, it is possible for ERROR SENT TO MACHINE LOG to flash to get the user’s attention by adding or editing the following line in the [QTPLASMAC] section of the <machine_name>.ini file:

There are a number of error messages printed by QtPlasmaC to inform the user of faults as they occur. The messages can be split into two groups, Critical and Warning.

Critical Errors will cause the running program to pause, and the operator will need to clear the cause of the error before proceeding.

If the error was received during cutting then forward or reverse motion is allowed while the machine is paused to enable the user to reposition the machine prior to resuming the cut.

When the error is cleared the program may be resumed.

These errors indicate the corresponding sensor was activated during cutting:

These errors indicate the corresponding sensor was activated before probing commenced:

The Arc OK signal was lost during cutting motion, before the M5 command was reached:

The Z axis reached the bottom limit before the work piece was detected:

The work piece is too high for any safe rapid removes:

One of these values in MATERIAL section of the PARAMETERS Tab is invalid (For example: if they are set to zero):

No arc has been detected after attempting to start the number of times indicated by Max Starts in the ARC frame of the CONFIGURATION section of the PARAMETERS Tab:

THC has caused the bottom limit to be reached while cutting:

THC has caused the top limit to be reached while cutting:

These errors indicate move to pierce height would exceed the Z Axis MAX_LIMIT for the corresponding probe method:

These errors indicate the move to pierce height would exceed the Z axis maximum safe height for the corresponding probe method:

Warning errors will not pause a running program and are informational only.

These errors indicate the corresponding sensor was activated before a probe test commenced:

This indicates that the corresponding sensor was activated during a consumable change:

This indicates that the corresponding sensor was activated during probe testing:

This indicates that probe contact was lost before probing up to find the zero point:

This indicates that the bottom limit was reached during a probe test:

This indicates that the move to pierce height would exceed the Z Axis MAX_LIMIT during the corresponding probe method:

This indicates that the safe height has been reduced due to THC raising the Z axis during cutting:

This indicates that the value for the Arc Voltage was invalid (NAN or INF) when QtPlasmaC launched.

QtPlasmaC update notices are posted at: https://forum.linuxcnc.org/plasmac/37233-plasmac-updates

Users are strongly encouraged to create a Username and subscribe to the above thread to receive update notices.

For a standard ISO installation, LinuxCNC will only be updated when a new minor release has been released. QtPlasmaC will then automatically update its configuration the first time it is run after a LinuxCNC update.

LinuxCNC is normally updated by entering the following commands into a terminal window (one at a time):

Enhancements and bug fixes will not be available on a standard installation until a new minor release of LinuxCNC has been released. If the user wishes to update whenever a new QtPlasmaC version has been pushed, they could use the LinuxCNC Buildbot repository rather than the standard LinuxCNC repository by following the instructions at: http://buildbot.linuxcnc.org/

Adding style changes to the default stylesheet is achieved by creating a file in the <machine_name> configuration folder. This file MUST be named qtplasmac_custom.qss. Any required style changes are then added to this file.

For example the user may want the arc voltage display in red, a green Torch On LED of a larger size and a larger Torch Enable button. This would be done with the following code in qtplasmac_custom.qss:

Custom stylesheets are enable by a setting in the [QTPLASMAC] section of the INI file with the filename of the stylesheet.

The filename may be any valid filename. The standard extension name is .qss but this is not mandatory.

There are some constraints on the custom stylesheet for QtPlasmaC, e.g. the jog buttons, cut-recovery buttons, and the conversational shape buttons are image files and are not able to be custom styled.

The custom style file requires a header in the following format:

The colors may be expressed in any valid stylesheet format.

The above colors are used for the following widgets. So any custom styling will need to take these into account. The colors shown below are the defaults used in QtPlasmaC along with the color name from the PARAMETERS Tab.

The user may return to the default styling at any time by following the following steps:

The next time QtPlasmaC is loaded all custom styling will be removed and the default styling will return.

Below is an example of the section to be deleted from qtplasmac.prefs:

The QtPlasmaC GUI offers user buttons that can be customized by adding commands in the <machine_name>.ini file.

The number of user buttons varies by display type and resolution as follows:

The user will need to run QtPlasmaC at the desired screen size to determine how many user buttons are available for use.

All <machine_name>.ini file settings for the buttons are found in the [QTPLASMAC] section.

The text that appears on the button is set the following way:

Where n is the button number and HAL Show is the text.

For text on multiple lines, split the text with a \

If an ampersand is required to be displayed as text then two consecutive ampersands are required:

Buttons can run the following:

External Commands

To run an external command, the command is preceded by a % character.

G-Code

To run G-Code, just enter the code to be run.

To run an existing subroutine.

<machine_name>.ini file variables can be entered by using {} (a space must be placed after the })

Multiple codes can be run by separating the codes with a \ symbol. The exception is the special commands which are required to be a single command per button.

External commands and G-Code may be mixed on the same button.

Toggle HAL Pin

The following code will allow the user to use a button to invert the current state of a HAL bit pin:

This code is required to be used as a single command and may only control one HAL bit pin per button.

The button colors will follow the state of the hal pin.

After setting the code, upon clicking, the button will invert colors and the HAL pin will invert pin state. The button will stay "latched" until the button is clicked again, which will return the button to the original colors and the HAL pin to the original pin state.

There are three External HAL Pins that are available to toggle as an output, the pin names are qtplasmac.ext_out_0, qtplasmac.ext_out_1, and qtplasmac.ext_out_2. HAL connections to these HAL pins need to be specified in a postgui HAL file as the Hal pins are not available until the QtPlasmac GUI has loaded.

It is possible for the user to mark a toggle-halpin button’s associated hal pin as being required to be turned "ON" before CYCLE START can be pressed by adding "runcritical" after the hal pin in the button code.

Toggle Alignment Laser HAL Pin

The following code will allow the user to use a button to invert the current state of the alignment laser HAL bit pin:

This code is also able to be used as a multiple command with g-code or external commands but may control only the alignment laser HAL bit pin.

The button colors will follow the state of the alignment laser hal pin.

After setting the code, upon clicking, the button will invert colors and the alignment laser HAL pin will invert pin state. The button will stay "latched" until the button is clicked again, which will return the button to the original colors and the alignment laser HAL pin to the original pin state.

The following code would allow the user to use a button to invert the current state of the alignment laser HAL bit pin and then move the X and Y axes to the offset for the alignment laser as specified in the <machine_name>.ini file:

The position of the "toggle-laser" command is not important as it is always the first command actioned regardless of position.

Pulse HAL Pin

The following code will allow the user to use a button to pulse a HAL bit pin for a duration of 0.5 seconds:

This code is required to be used as a single command and may only control one HAL bit pin per button.

The pulse duration is specified in seconds, if the pulse duration is not specified then it will default to one second.

The button colors will follow the state of the hal pin.

After setting the code, upon clicking the button, the button will invert colors, the HAL pin will invert pin state, and the time remaining will be displayed on the button. The button color and the pin state will stay inverted until the pulse duration timer has completed, which will return the button to the original colors, the HAL pin to the original pin state, and the original button name.

An active pulse can be canceled by clicking the button again.

There are three External HAL Pins that are available to pulse as an output, the pin names are qtplasmac.ext_out_0, qtplasmac.ext_out_1, and qtplasmac.ext_out_2. HAL connections to these HAL pins need to be specified in a postgui HAL file as the Hal pins are not available until the QtPlasmac GUI has loaded.

Probe Test

QtPlasmaC will begin a probe and when the material is detected, the Z axis will rise to the Pierce Height currently displayed in the MATERIAL section of the PARAMETERS Tab. If the user has "View Material" selected in the GUI SETTINGS section of the PARAMETERS Tab, this value will be displayed in the top left corner of the PREVIEW Window next to PH:.

QtPlasmaC will then wait in this state for the time specified (rounded to no decimal places) before returning the Z axis to the starting position. An example of a 6 second delay is below. If there is no time specified then the probe time will default to 10 seconds.

Ohmic Test

QtPlasmaC will enable the Ohmic Probe Enable output signal and if the Ohmic Probe input is sensed, the LED indicator in the SENSOR Panel will light. The main purpose of this is to allow a quick test for a shorted torch tip.

Cut Type

This button if selected will toggle between the two cut types, Pierce and Cut (default cutting mode) or Pierce Only.

Change Consumables

Pressing this button moves the torch to the specified coordinates when the machine is paused to allow the user easy access to change the torch consumables.

Valid entries are Xnnn Ynnn Fnnn. Feed Rate (F) is mandatory and at least one of the X or Y coordinates are required.

The X and Y coordinates are in absolute machine coordinates. If X or Y are missing then the current coordinate for that axis will be used.

There are three methods to return to the previous coordinates:

Load

Loading a G-Code program from the directory specified by the PROGRAM_PREFIX variable in the <machine_name>.ini file (usually ~/linuxcnc/nc_files) is possible by using the following format:

If the user’s G-Code file is located in a sub-directory of the PROGRAM_PREFIX directory, it would be accessed by adding the sub-directory name to the beginning of the G-Code file name. Example for a sub-directory named plasma:

Note that the first "/" is not necessary as it will be added automatically.

Torch Pulse

Pulse the torch on for a predetermined time. The time must be specified in seconds using up to one decimal place. The maximum allowable time is 3 seconds, anything specified above that value will be limited to 3 seconds. An example of a 0.5 second pulse is below. It there is no time specified then it will default to 1 second. Pulse times with more than one decimal place will be rounded to one decimal place.

Pressing the button again during the countdown will cause the torch to be turned off, as will pressing Esc if keyboard shortcuts are enabled in the PARAMETERS Tab.

If the button is released before the countdown is complete then the torch will turn off at countdown completion, holding the button on until after the countdown has completed will cause the torch to remain on until the button has been released.

Single Cut

Run a single unidirectional cut. This utilises the automatic Single Cut feature.

Framing

Framing is the ability to move the torch around the perimeter of a rectangle that encompasses the bounds of the current job.

The laser enable HAL pin (qtplasmac.laser_on) will be enabled during the framing moves and any X/Y offsets for the laser pointer in the <machine_name>.ini file will also be applied to the X/Y motion.

Upon starting a Framing cycle, it is important to note that by default the Z axis will be moved to a height of [AXIS_Z]MAX_LIMIT - 5mm before X/Y motion begins.

The velocity for the XY movements of the Framing motion can be specified so that Framing motion always occurs at a set velocity. This can be achieved by adding the feed rate (F) as the as the last portion of the button code. If the feed rate is omitted from the button code, Framing motion velocity will default to the feed rate for the currently selected material.

The following GUI buttons and Keyboard Shortcuts (if enabled in the PARAMETERS Tab) are valid during Framing motion:

It is possible for the user to omit the initial default Z movement and run the framing sequence at the current Z height by adding "usecurrentzheight" after "framing".

To specify a feed rate:

or:

Enabling a user button as a Framing button will add an external HAL pin that may be connected from a pendant etc. HAL connections to this HAL pin needs to be specified in a postgui HAL file as the Hal pin is not available until the QtPlasmac GUI has loaded.

Manual Cut

Manual Cut functions identically to the F9 button to begin or end a manual cut.

Offset Viewer

This allows the showing/hiding of an offset viewing screen that displays all machine offsets. All relative offsets can be edited and the G54 ~ G59.3 work system coordinates are able to be given custom names.

[underline]*Load Latest File

this allows the loading of the last modified file in a directory. The directory name is optional and if omitted will default to the last directory a file was loaded from.

Use the following sequence to set the offsets for a laser, camera, or scribe:

Cancelling may be done at any stage by pressing the CANCEL button which will close the dialog and no changes will be saved.

By default, QtPlasmaC will remove all Z motion from a loaded G-Code file and add an initial Z movement to bring the torch near the top of travel at the beginning of the file. If the user wishes to use their table with a marker, a drag knife, diamond scribe, etc. mounted in the torch holder, QtPlasmaC has the ability to retain the Z movements when executing a program by adding the following command in a G-Code file:

Omitting this command, or setting this value to anything but 1 will cause QtPlasmaC to revert to the default behavior of stripping all Z motion from a loaded G-Code file and making an initial Z movement to bring the torch near the top of travel at the beginning of the file.

QtPlasmaC creates some HAL pins that may be used to connect a momentary external button or pendant etc.

HAL connections to these HAL pins need to be specified in a postgui HAL file as the Hal pins are not available until the QtPlasmac GUI has loaded.

The following HAL bit pins are always created. The HAL pin has the identical behaviour of the related QtPlasmaC GUI button.

The following HAL pins which allow the use of an MPG to control height override are always created.

The following HAL bit pins are only created if the function is specified in a custom user button. The HAL pin has the identical behaviour of the related custom user button.

The following HAL bit output pins are always created and can be used by either the Toggle HAL Pin or Pulse HAL Pin custom user buttons to change the state of an output.

If the user has external buttons and/or a pendant that emulates any of the program buttons, CYCLE START, CYCLE PAUSE, or CYCLE STOP then it is possible to hide any or all of these GUI program buttons by adding the following code to the [QTPLASMAC] section of the <machine_name>.ini file:

For the 16:9 or 4:3 GUIs, the hiding of each of these GUI buttons will expose two more custom user buttons in the GUI.

Void sensing may be further tuned by adjusting the required number of consecutive times that the threshold has been exceeded before applying the void lock to the THC.

The HAL pin for adjusting this is named plasmac.kerf-errors-max and the default value is 2. To change this value, add the pin and the required value to the custom.hal file. The following example would set the required number of consecutive times to exceed the threshold to 3:

Some plasma power sources/machine configurations may lose the Arc OK signal either momentarily during a cut, or permanently near the end of a cut causing QtPlasmaC to pause the program and report a "valid arc lost" error. There is a HAL pin named plasmac.arc-lost-delay that may be used to set a delay (in seconds) that will prevent a paused program/error if the lost Arc OK signal is regained, or the M5 command is reached before the set delay period expires. It is important to note that the THC will be disabled and locked at the cutting height at the time the Arc OK signal was lost.

The following code would set a delay of 0.1 seconds:

It is recommended that the user set this pin in the custom.hal file.

This setting should only be used if the user experiences the above symptoms. It should also be noted that the user could use the appropriate Ignore Arc OK G-Code commands to achieve a similar result.

Mode 0 Arc OK relies on the arc voltage to set the Arc OK signal. This is accomplished by sampling the arc voltage every servo thread cycle. There needs to be a specified number of consecutive samples all within a specified threshold for the Arc OK signal to be set. These voltages are also required to be within a specified range.

There are two settings in the PARAMETERS Tab for setting the range, these are:

Both of these values may be changed by direct entry or by the use of the increment/decrement buttons.

There are also two HAL pins that have been provided to allow the user to tune the set point. These HAL pins are:

The following example would set the number of valid consecutive readings required to 6:

Small fluctuations in the arc voltage displayed while the machine is at idle are possible depending on many different variables (electrical noise, incorrect THCAD tuning, etc.). After all contributing factors have been mitigated, if a small fluctuation still exists it is possible to eliminate it by widening the voltage window for which QtPlasmaC will display 0v.

The pin for adjusting this value is named plasmac.zero-window and the default value is set to 0.1. To change this value, add the pin and the required value to the custom.hal file. The following example would set the voltage window to be displayed as 0v from -5v to +5v:

Max Offset is the distance (in millimeters) away from the Z MAX_LIMIT that QtPlasmaC will allow the Z axis to travel while under machine control.

The pin for adjusting this value is named plasmac.max-offset and the default value (in millimeters) is set to 5. To change this value, add the pin and the required value to the custom.hal file. It is not recommended to use values less than 5mm as offset overrun may cause unforeseen issues.

The following example would set the distance from Z MAX_LIMIT to 10mm:

The plasmac HAL component has a HAL pin named plasmac.state-out which can be used to interface with user-coded components to provide the current state of the component.

The different states QtPlasmaC could encounter are as follows:

The DEBUG state is for testing purposes only and will not normally be encountered.

The plasmac HAL component has a HAL pin named plasmac.debug-print which if set to 1 (true) will print to terminal every state change as a debug aid.

Communications can be established with a Hypertherm PowerMax plasma cutter that has a RS485 port. This feature enables the setting of Cut Mode, Cutting Amperage and Gas Pressure automatically from the Cut Parameters of the material file. In addition, the user will be able to view the PowerMax’s Arc On Time in hh:mm:ss format on the STATISTICS Tab.

If Gas Pressure is set to Zero then the PowerMax will automatically calculate the required pressure from the Cut Mode, Cut Current, torch type, and torch length.

Changing the cutting mode will set the gas pressure to zero causing the machine to use its automatic gas pressure mode.

The maximum and minimum values of these parameters are read from the plasma cutter and the related spin-buttons in the Cut Parameters are then limited by these values. Gas pressure cannot be changed from zero until communications have been established.

This feature is enabled by setting the correct port name for the PM_PORT variable in the [QTPLASMAC] section of the <machine_name>.ini file. If the PM_PORT variable is not set in the <machine_name>.ini file then the widgets associated with this feature will not be visible.

Example showing enabling the Hypertherm PowerMax Communications on USB0:

If the user is unsure of the name of the port, there is a python script in the configuration directory that will show all available ports and can also be used to test communications with the plasma unit prior to enabling this feature in the QtPlasmaC GUI.

To use the test script follow these instructions:

For a package installation (Buildbot) enter the following command in a terminal window:

For a run in place installation enter the following two commands in a terminal window:

The gas pressure units display (psi or bar) is determined by the data received during initial setup of the communication link and is then shown next to the Gas Pressure setting in the MATERIAL section of the PARAMETERS Tab.

The PowerMax machine will go into remote mode after communications have been established and may only be controlled remotely (via the QtPlasmaC GUI) at this point. The connection can be validated by observing the PowerMax display.

To switch the PowerMax back to local mode the user can either:

To install pyserial, enter the following command into a terminal window:

A typical connection diagram is shown in the appendix of this document as well as confirmed working interfaces.

There are example configuration files which use the QtPlasmaC GUI to simulate plasma cutting machines.

They can be found in the LinuxCNC chooser under: Sample Configurations -> by_machine -> qtplasmac

Three versions are available in both metric and imperial units:

Each sample configuration includes a popup control panel to simulate various inputs to the GUI such as:

There are some sample G-Code files in nc_files/plasmac.

It is recommended that a backup copy of the existing QtPlasmaC configuration is made before proceeding.

To change the type of LinuxCNC installation from a Package installation (Buildbot) to a Run In Place or vice versa the user will need to run the qtplasmac-setup program.

Enter the following command into a terminal window do one of the following:

Switch to a Package installation (Buildbot):

Switch to a Run In Place installation:

This will load the setup program:

press SELECT which will open a file dialog box, select the .ini file of the QtPlasmaC configuration then press SWITCH. The installation type will now be changed.

The Mesa THCAD is a common way of obtaining the arc voltage from a plasma cutter and is also useful for ohmic sensing of the material during probing. The THCAD may be used for parallel port configurations as well as configurations using Mesa Electronics hardware. The THCAD is available in three different models, THCAD-5, THCAD-10, and THCAD-300.

There is a mode jumper on each THCAD card which should be set to UNIPOLAR

There is a frequency divider jumper on each THCAD card which should be set according to the hardware type:

This value is required to be entered into PNcConf during installation.

Located on the rear of the THCAD is a calibration sticker showing:

or similar values, these values are required to be entered into PNcConf during installation.

PNcConf has entries for all required THCAD parameters and will calculate and configure any required settings. The calculations used are as follows:

Voltage Scale

Voltage Offset

r = divider ratio (see below).

f = full scale value from calibration sticker.

z = 0V value from calibration sticker.

d = value from jumper above.

v = full scale voltage of THCAD

Divider Ratio

THCAD-5 or THCAD-10

If connecting to a plasma CNC port then the divider ratio is selected from the plasma machine. A common ratio used is 20:1

If connecting to the plasma machines full arc voltage then a common setup for a THCAD-10 is to use a 1 Megohm resistor from arc negative to THCAD negative and a 1 Megohm resistor from arc positive to THCAD positive. The divider ratio is obtained by:

THCAD-300

Hypertherm RS485 Wiring Diagram (wire colors inside the Hypertherm in parentheses):

RS485 interfaces that are known to work:

DTECH DT-5019 USB to RS485 converter adapter:

The following is necessary to convert a motherboard Serial connection or Serial card (RS232) to RS485:

DTECH RS232 to RS485 converter:

Serial card example (Sunnix SER5037A PCI Card shown with Breakout Board):

An effective and very reliable method of obtaining an Arc OK signal from a plasma power supply without a CNC port is to mount a reed relay inside a non-conductive tube and wrap and secure three turns of the work lead around the tube.

This assembly will now act as a relay that will switch on when current is flowing through the work lead which only occurs when a cutting arc has been established.

This will require that QtPlasmaC be operated in Mode 1 rather than Mode 0. See the INI File and QtPlasmaC Modes sections for more information.

A full description is at Contact Load

There is a known issue with some combinations of hardware and keyboards that may affect the autorepeat feature of the keyboard and will then affect keyboard jogging by intermittent stopping and starting during jogging. This issue can be prevented by disabling the Operating System’s autorepeat feature for all keys. QtPlasmaC uses this disabling feature by default for all keys only when the MAIN Tab is visible, with the following exceptions when autorepeat is allowed with the MAIN Tab visible: G-Code editor is active, MDI is active. When QtPlasmaC is shut down, the Operating System’s autorepeat feature will be enabled for all keys.

If the user wishes to prevent QtPlasmaC from changing the Operating System’s autorepeat settings, enter the following in the [QTPLASMAC] section of the <machine_name>.ini file:

This issue does not affect any jogging using the GUI jog buttons.