As a nub in Python I struggled quit a while finding the way to get data from Unitronics PLC to my computer. all of our technicians at work where abroad and i did not want to bother them . nun of us worked with python before.
I tried opc and then stumbled on modbus-tk (tool kit) python library.
so here is my solution.
on the PLC side you need to set the PLC to allow Modbus connection like so:
set plc name, card socket (use socket 2 port 502 as it is the default and unitronics asked you to :).
set the network id and remember it for the python code this is the slave number.
rung 2 sets the Modbus scan to work always so you will refresh values every PLC cycle.
on the python side :
install modbus_tk : pip install modbus_tk
reading values works with this code
import modbus_tk.defines as cst import modbus_tk.modbus as modbus import modbus_tk.modbus_tcp as modbus_tcp master = modbus_tcp.TcpMaster(host='172.21.2.183', port=502, timeout_in_sec=5.0) master.open actual_bytes = master.execute(slave=1, function_code=cst.READ_COILS, starting_address=1, quantity_of_x=25) print("actual_bytes =", actual_bytes) master.close
this code reads MI:1 to MI:26
Hope in the future I will have time to explain how to read other data.
