I have installed one PCM301 alongwith CPU374 for serial communication with 2 slave devices on RS485. This system was working since last 5 years. Few days back the communication between PCM and 2 slave devices got broke up for unknown reasons. Following is the sequence of checks i have done.
1) First i checked all the cables and found that all cables were ok.
2) I installed the master file again and tried to restablish the communication. but it didnt worked out.
3) I checked both the slave devices by connecting them with my PC using serial converter (232 to 485) and both were communicating with PC on 485.
4) I installed the master file again and tried to restablish the communication. but it didnt worked out.
5) I had spare PCM card, I installed the same and tried to restablish the communication. but it didnt worked out.
6) I changed the rack of the system but it didnt worked out.
7) For trials i connected one of slave devices with PCM card on RS232. and it started communicating with the PCM.
8) I again tried to establish the communication on RS485 but it didnt worked out.
9) Previously my network was without terminating resistance. I even connected one terminating resistance but it didnt worked out.
10) LED blinking pattern of PCM seems to be normal.
If anybody has faced any problems like this, then please revert back.
Regards,
Mayank
1) First i checked all the cables and found that all cables were ok.
2) I installed the master file again and tried to restablish the communication. but it didnt worked out.
3) I checked both the slave devices by connecting them with my PC using serial converter (232 to 485) and both were communicating with PC on 485.
4) I installed the master file again and tried to restablish the communication. but it didnt worked out.
5) I had spare PCM card, I installed the same and tried to restablish the communication. but it didnt worked out.
6) I changed the rack of the system but it didnt worked out.
7) For trials i connected one of slave devices with PCM card on RS232. and it started communicating with the PCM.
8) I again tried to establish the communication on RS485 but it didnt worked out.
9) Previously my network was without terminating resistance. I even connected one terminating resistance but it didnt worked out.
10) LED blinking pattern of PCM seems to be normal.
If anybody has faced any problems like this, then please revert back.
Regards,
Mayank