plcforum.uz.ua

Hi

I am involved in a project consisting S7-315 2DP, 3 ET200M, 5 ACS800, 8 ACS550, and WinCC station as a PLC commisioner and programmer. Which are all connected through Profibus.

ABB drives are equipped with RPBA-01. Design of the electrical cabins are in a way that drives are powered up with a contactor by PLC and then starts whenever is needed by Profibus.

The problem is when RPBA-01 powers up PLC goes to stop mode. So, contactor switches off and drive powers down as a result. I managed to use external power for RMIO in ACS800 drives, and ACS800's problem is solved. RPBA-01 in ACS800 drives is always powered on and there is no fault on PLC, but still when ACS550 drives are powered up PLC goes to stop mode. I would be grateful if anyone could guide me or recommend a solution for this problem.

I should mention the settings in ABB drives are correct. If drive's powering up contactor is bypassed, the first time RPBA-01 powers up there will be a fault in the PLC, but when PLC's fault is reset everything works prefect. Problem arises when RPBA-01 powers up during PLC's run mode, if RPBA-01 powers up before PLC starts there will be no problem.

I appreciate your kind response in advance.

Regards
Mojtaba Azarnoosh

I think you need to try using diagnostic OB in the STEP 7 program.

Thanks for your response.
Unfortunately I'm not at the site right now.
I'll try as soon as possible.