virtous_77,
The most likely cause for a "PLC Not Responding" error is that you have lost the communications between the PLC and the GP2400 touch screen. Stepping down through the troubleshooting matrix, the most likely reason for losing communications is your cable is unplugged or loose. Next most likely is your PLC is not in run mode, has faulted, or has lost its power supply. Third, someone may have changed the communications setup parameters to be incorrect. Fourth, you have a malfunction, wither at the touch screen, or at the PLC.
