Hi every body,

I am facing some problem of communication from RIO to PLC. In RIO Panel we are using Redundancy bundle (IM153-2) which is connected to Profibus OLM (G12) thorough profibus cable. (Please see the attached network architecture). OLM is communicating through Fiber optic cable to the main PLC Panel. So we have two profibus OLM in the RIO panel and two FO cable network coming from PLC. Each OLM is connected to  respective FO cable network. Each OLM profibus port is connected to the respective slot of IM153-2 in RIO panel. Two Optical channel of the one OLM is not working because of either FO cable termination is wrong or OLM is faulty. another OLM is working and communicating to PLC.

 Every night we are observing communication break between RIO panel and PLC.  This is happening in the night time only.We observed that, suddenly Channel No. 2 LED on the Working OLM and ACT LED on the IM153-2 LED turning OFF and ON again during the communication break. This panel is receiving the supply from electrical voltage distribution panel. we switched off all the MCB in the panel and kept ON only one MCB which is giving power to the RIO Panel. we found that this communication break problem is resolved.

other MCB's in the Electrical distribution panel are giving supply to the field instruments. However , we need to turn ON the MCB's which is giving supply to field instruments. but if we turn ON these MCB's, again the communication break problem will occur.

Can we give the supply to RIO panel from other Electrical voltage distribution panel to avoid any noise..??

I already replaced the IM153-2 module with new one. is there any problem with working OLM..??

Please help me to resolve this problem...Thanks in advance.

Regards

Sacheen