A dedicated service that take modbus command from ROS to modbusTCP. This service should be run after the main ROS application is launched.

This service subscribes to ROS topic /modbus_tcp_cmd and detects incomming commands. If the incomming message is a read command, the service publishs the modbus response to ROS topic /modbus_tcp_data.

This service requires rospy, pymodbus to run. The installation command should be:

sudo pip install -r requirements.txt

The read commands must follow the following format:

• READ [register address] COUNT [# of registers]

For example:

• READ 0x0426 COUNT 4

If the read command is issued successfully, the response is then publish to /modbus_tcp_data:

• [1, 2341, 1, 3122]

The write commands must follow the following format:

• WRITE [register address] COUNT [# of regiser] [list of unsigned-16-bit integer (uint_16[])]

For example:

• WRITE 0x1620 COUNT 3 1 100 200