Posted ByMike Bargnesi on January 10, 2002 at 20:09:43:
I am using a Momentum 1760 00 style processor and i am trying to use a PC to communicate to PLC on Modbus port 1. The PC is 205 feet from the plc so I bought a B&B rs232/485 converter for both ends (PC & PLC) I have a Null modem connected at the PLC side and a standard RS-232 9pin to 25 pin cable at the PC side. I am able to read data from the PLC but I can not send any commands down to the PLC from the PC. Using ProworxNxt I get an error message that states I am not logged on to the PLC, Using LOOKOUT software I see the values update dynamically but if I turn a switch on/off it does not get sent to the PLC.