MB2HAL is a generic userspace HAL component to communicate with one or more Modbus devices. So far, there are two options to communicate with a Modbus device:

  1. One option is to create a HAL component as a driver see VFD Modbus.

  2. Another option is to use Classic Ladder which has Modbus built in see ClassicLadder.

  3. Now there is a third option that consists of a "generic" driver configured by text file, this is called MB2HAL. Why MB2HAL ? Consider using Mb2hal if:

    • You have to write a new driver and you don’t know anything about programming.

    • You need to use Classic Ladder "only" to manage the Modbus connections.

    • You have to discover and configure first time the Modbus transactions. Mb2hal have debug levels to facilitate the low level protocol debug.

    • You have more than one device to connect. Mb2hal is very efficient managing multiple devices, transactions and links. Currently i am monitoring two axis drivers using a Rs232 port, a VFD driver using another Rs232 port, and a remote I/O using TCP/IP.

    • You want a protocol to connect your Arduino to HAL. Look the included sample configuration file, sketch and library for Arduino Modbus.

1. Example config file.

#This .INI file is also the HELP, MANUAL and HOW-TO file for mb2hal.

#Load the modbus HAL userspace module as the examples below,
#change to match your own HAL_MODULE_NAME and .ini file name
#Using HAL_MODULE_NAME=mb2hal or nothing (default): loadusr -W mb2hal config=config_file.ini
#Using HAL_MODULE_NAME=mymodule: loadusr -Wn mymodule mb2hal config=config_file.ini

#Common section

[MB2HAL_INIT]

#OPTIONAL: Debug level of init and INI file parsing.
# 0 = silent.
# 1 = error messages (default).
# 2 = OK confirmation messages.
# 3 = debugging messages.
# 4 = maximum debugging messages (only in transactions).

INIT_DEBUG=3

#OPTIONAL: HAL module (component) name. Defaults to "mb2hal".

HAL_MODULE_NAME=mb2hal

#OPTIONAL: Insert a delay of "FLOAT seconds" between transactions in order
#to not to have a lot of logging and facilitate the debugging.
#Useful when using DEBUG=3 (NOT INIT_DEBUG=3)
#It affects ALL transactions.
#Use "0.0" for normal activity.

SLOWDOWN=0.0

#REQUIRED: The number of total Modbus transactions. There is no maximum.

TOTAL_TRANSACTIONS=9

#One transaction section is required per transaction, starting at 00 and counting up sequentially.
#If there is a new link (not transaction), you must provide the REQUIRED parameters 1st time.
#Warning: Any OPTIONAL parameter not specified are copied from the previous transaction.

[TRANSACTION_00]

#REQUIRED: You must specify either a "serial" or "tcp" link for the first transaction.
#Later transaction will use the previous transaction link if not specified.

LINK_TYPE=tcp

#if LINK_TYPE=tcp then REQUIRED (only 1st time): The Modbus slave device ip address.
#if LINK_TYPE=serial then IGNORED

TCP_IP=192.168.2.10

#if LINK_TYPE=tcp then OPTIONAL.
#if LINK_TYPE=serial then IGNORED
#The Modbus slave device tcp port. Defaults to 502.

TCP_PORT=502

#if LINK_TYPE=serial then REQUIRED (only 1st time).
#if LINK_TYPE=tcp then IGNORED
#The serial port.

SERIAL_PORT=/dev/ttyS0

#if LINK_TYPE=serial then REQUIRED (only 1st time).
#if LINK_TYPE=tcp then IGNORED
#The baud rate.

SERIAL_BAUD=115200

#if LINK_TYPE=serial then REQUIRED (only 1st time).
#if LINK_TYPE=tcp then IGNORED
#Data bits. One of 5,6,7,8.

SERIAL_BITS=8

#if LINK_TYPE=serial then REQUIRED (only 1st time).
#if LINK_TYPE=tcp then IGNORED
#Data parity. One of: even, odd, none.

SERIAL_PARITY=none

#if LINK_TYPE=serial then REQUIRED (only 1st time).
#if LINK_TYPE=tcp then IGNORED
#Stop bits. One of 1, 2.

SERIAL_STOP=2

#if LINK_TYPE=serial then OPTIONAL:
#if LINK_TYPE=tcp then IGNORED
#Serial port delay between for this transaction only.
#In ms. Defaults to 0.

SERIAL_DELAY_MS=10

#REQUIRED (only 1st time).
#Modbus slave number.

MB_SLAVE_ID=1

#REQUIRED: The first element address.

FIRST_ELEMENT=0

#REQUIRED: The number of elements.

NELEMENTS=16

#REQUIRED: Modbus transaction function code (see www.modbus.org specifications).
#    fnct_01_read_coils               (01 = 0x01)
#    fnct_02_read_discrete_inputs     (02 = 0x02)
#    fnct_03_read_holding_registers   (03 = 0x03)
#    fnct_04_read_input_registers     (04 = 0x04)
#    fnct_05_write_single_coil        (05 = 0x05)
#    fnct_06_write_single_register    (06 = 0x06)
#    fnct_15_write_multiple_coils     (15 = 0x0F)
#    fnct_16_write_multiple_registers (16 = 0x10)

#fnct_01_read_coils and
#fnct_02_read_discrete_inputs: creates boolean output HAL pins 'bit' and 'bit-inv'.
#fnct_03_read_holding_registers and
#fnct_04_read_input_registers: creates floating point output HAL pins 'float'.
#                         also creates u32 output HAL pins 'int'.
#fnct_05_write_single_coil:    creates a boolean input HAL pin 'bit'
#       NELEMENTS needs to be 1 or PIN_NAMES must contain just one name
#fnct_06_write_single_register: creates a floating point input HAL pin 'float'
#                          also creates a u32 input HAL pin 'int'.
#       NELEMENTS needs to be 1 or PIN_NAMES must contain just one name
#   Both pin values are added and limited to 65535 (UINT16_MAX). Normally use one and let the other open (read as 0).
#fnct_15_write_multiple_coils: creates boolean input HAL pins 'bit'.
#fnct_16_write_multiple_registers: creates floating point input HAL pins 'float'.
#                             also creates u32 input HAL pins 'int'.
#    Both pin values are added and limited to 65535 (UINT16_MAX). Normally use one and let the other open (read as 0).

#The pins are named based on component name, transaction number and order number.
#Example: mb2hal.00.01.<type> (transaction=00, second register=01 (00 is the first one))
MB_TX_CODE=fnct_03_read_holding_registers

#OPTIONAL: Response timeout for this transaction. In INTEGER ms. Defaults to 500 ms.
#This is how much to wait for 1st byte before raise an error.

MB_RESPONSE_TIMEOUT_MS=500

#OPTIONAL: Byte timeout for this transaction. In INTEGER ms. Defaults to 500 ms.
#This is how much to wait from byte to byte before raise an error.

MB_BYTE_TIMEOUT_MS=500

#OPTIONAL: Instead of giving the transaction number, use a name.
#Example: mb2hal.00.01 could become mb2hal.plcin.01
#The name must not exceed 28 characters.
#NOTE: when using names be careful that you dont end up with two transactions
#using the same name.

HAL_TX_NAME=remoteIOcfg

#OPTIONAL: Maximum update rate in HZ. Defaults to 0.0 (0.0 = as soon as available = infinit).
#NOTE: This is a maximum rate and the actual rate may be lower.
#If you want to calculate it in ms use (1000 / required_ms).
#Example: 100 ms = MAX_UPDATE_RATE=10.0, because 1000.0 ms / 100.0 ms = 10.0 Hz

MAX_UPDATE_RATE=0.0

#OPTIONAL: Debug level for this transaction only.
#See INIT_DEBUG parameter above.

DEBUG=1

#While DEBUGGING transactions note the returned "ret[]" value correspond to:
#/* Modbus protocol exceptions */
#ILLEGAL_FUNCTION        -0x01 the FUNCTION code received in the query is not allowed or invalid.
#ILLEGAL_DATA_ADDRESS    -0x02 the DATA ADDRESS received in the query is not an allowable address for the slave or is invalid.
#ILLEGAL_DATA_VALUE      -0x03 a VALUE contained in the data query field is not an allowable value or is invalid.
#SLAVE_DEVICE_FAILURE    -0x04 SLAVE (or MASTER) device unrecoverable FAILURE while attempting to perform the requested action.
#SERVER_FAILURE          -0x04 (see above).
#ACKNOWLEDGE             -0x05 This response is returned to PREVENT A TIMEOUT in the master.
#                              A long duration of time is required to process the request in the slave.
#SLAVE_DEVICE_BUSY       -0x06 The slave (or server) is BUSY. Retrasmit the request later.
#SERVER_BUSY             -0x06 (see above).
#NEGATIVE_ACKNOWLEDGE    -0x07 Unsuccessful programming request using function code 13 or 14.
#MEMORY_PARITY_ERROR     -0x08 SLAVE parity error in MEMORY.
#GATEWAY_PROBLEM_PATH    -0x0A (-10) Gateway path(s) not available.
#GATEWAY_PROBLEM_TARGET  -0x0B (-11) The target device failed to repond (generated by master, not slave).
#/* Program or connection */
#COMM_TIME_OUT           -0x0C (-12)
#PORT_SOCKET_FAILURE     -0x0D (-13)
#SELECT_FAILURE          -0x0E (-14)
#TOO_MANY_DATAS          -0x0F (-15)
#INVALID_CRC             -0x10 (-16)
#INVALID_EXCEPTION_CODE  -0x11 (-17)

[TRANSACTION_01]
MB_TX_CODE=fnct_02_read_discrete_inputs
FIRST_ELEMENT=1024
NELEMENTS=24
HAL_TX_NAME=remoteIOin
MAX_UPDATE_RATE=0.0
DEBUG=1

[TRANSACTION_02]
MB_TX_CODE=fnct_15_write_multiple_coils
FIRST_ELEMENT=1280
NELEMENTS=8
HAL_TX_NAME=remoteIOout
MAX_UPDATE_RATE=0.0

[TRANSACTION_03]
LINK_TYPE=serial
SERIAL_PORT=/dev/ttyS0
SERIAL_BAUD=115200
SERIAL_BITS=8
SERIAL_PARITY=none
SERIAL_STOP=2
SERIAL_DELAY_MS=50
MB_SLAVE_ID=1
MB_TX_CODE=fnct_03_read_holding_registers
FIRST_ELEMENT=1
NELEMENTS=2
HAL_TX_NAME=XDrive01
MAX_UPDATE_RATE=0.0
DEBUG=1

[TRANSACTION_04]
MB_TX_CODE=fnct_03_read_holding_registers
FIRST_ELEMENT=4
NELEMENTS=3
HAL_TX_NAME=XDrive02
MAX_UPDATE_RATE=0.0
DEBUG=1

[TRANSACTION_05]
MB_TX_CODE=fnct_03_read_holding_registers
FIRST_ELEMENT=9
NELEMENTS=1
HAL_TX_NAME=XDrive03
MAX_UPDATE_RATE=0.0

[TRANSACTION_06]
MB_TX_CODE=fnct_03_read_holding_registers
FIRST_ELEMENT=1024
NELEMENTS=1
HAL_TX_NAME=XDrive04
MAX_UPDATE_RATE=0.0

[TRANSACTION_07]
MB_TX_CODE=fnct_03_read_holding_registers
FIRST_ELEMENT=1030
NELEMENTS=2
HAL_TX_NAME=XDrive05
MAX_UPDATE_RATE=0.0

[TRANSACTION_08]
MB_TX_CODE=fnct_03_read_holding_registers
FIRST_ELEMENT=1033
NELEMENTS=1
HAL_TX_NAME=XDrive06
MAX_UPDATE_RATE=0.0