Computer(s) won't see PLC any more - Please help

[paigeh]

Hi,

I hope someone can help! We have programmed the PLC, and have been communicating with the computer via a 9-pin RS232 cable. Things were working fine, and we updated the program successfully several times. Now, however, the computer will no longer recognize the PLC. We have tried using a different cable, and we even tried two other computers. We have a critical update that has to be done, and we can?t get to it.

Thanks for your help! You can?t imagine how happy we will be when we solve this!

[support]

What PLC model? If it is M-series is it because the PLC program has changed the comm port settings? Tried to turn ON DIP switch #4, reset the PLC and use TLServer (with baud rate set to 9600) to type in "IR*" at the serial port setup page and see if you get a response. If so, clear the PLC program with a blank program, turn OFF dip switch #4 and put TLServer baud rate back to 38,400bps and things will work normally again.