We have an older Modicon A984-145 with P-120 power supply, a 5-slot rack and two I/O cards from a previous project that I would like to use for a new project. When I drafted the program in ProWorx NT and configured the controller settings in the program, everything looked fine. However, when I attempted to power up the PLC and download the program I discovered that the CPU will not function. I have a good power input from the P-120 and the green LED on the power board is lit. But the Ready, Run, Modbus, and Modbus Plus LED's will not light.
I tried to download to the unit from my laptop using the serial port and a Null-modem cable to the Modbus port on the PLC but it will not communicate (time-out errors).
Is the fact that the Ready is out indicative of a "Dim Awareness" condition in the PLC? And if so, how can I download the program to the CPU if the Modbus comms will not respond? Any ideas?
I tried to download to the unit from my laptop using the serial port and a Null-modem cable to the Modbus port on the PLC but it will not communicate (time-out errors).
Is the fact that the Ready is out indicative of a "Dim Awareness" condition in the PLC? And if so, how can I download the program to the CPU if the Modbus comms will not respond? Any ideas?