Problem with PLC?

[sid80555]

i am not receiving any kind of response from my FMD88-10 PLC when i connect it using RS232 cable.It was working fine all these days but now its not responding at all.I can see the RTC error LED glowing does this mean something?I am in the UK and my project deadline is soon approaching:(

[support]

Most likely you may have loaded a bad program into the PLC and is causing communication problem.

What you can try to do is to turn DIP switch #4 to ON and reset the PLC (power off and ON). The PLC should start up with the "PAUSE" light ON and it means it is not running the user program. Now try to use TLServer to communicate with the PLC again. If it works then overwrite whatever program inside the PLC with a blank program. You would then have recovered the PLC from error condition.

If this still does not work, then it could be a bad DB9 cable, a bad USB-RS232 connector (What brand of USB-RS232 converter are you using?), or a bad RS232 chip (ST232 or MAX232) on the PLC.

Rgds

[support]

From your other post on this forum it appears that you are trying to use COMM1 port to communicate with GSM modem. If that is the case then you will not be able to use the same COMM port for online monitoring via TLServer since the PLC is sending different data out of the COMM port from what the TLServer would expect when it send a command and waiting for a response. That would cause COMM failure.

If you are using FMD88-10 you can communicate with the PLC via the Ethernet port or the RS485 port and leave RS232 port dedicated to communicating with the modem.