Problems with profibus net. (UPS and active terminators)

Once a month, in our factory, the power is shut off for about 40 minutes ( faults, repairers etc.). After the faults I have problem with automatic reawaking the profibus net and visualization system with WinCC server. Industrial net is built with Siemens PLC’s (S7300), few computers with visualization, control and server which task is to archive information and visualization when needed.



Few months ago UPS with active termination was installed – placed where in profibus nets is needed - we suspect that the WinCC server Siemens card after reawaking the supply and reconfiguring the net has some errors because always server restart is the solution. This terminator task was to help server reconnect with PLCs.



It seems that it doesn’t help, we still have to restart the WinCC server to recover the profibus net.



Please give me some hints.



Thank you in advance.

Daniel

http://www.plctalk.net/qanda/newthread.php?do=newthread&f=2

You mention you have WinCC server, S7-300s and a "few" computers. I remember once seeing restart issues on a Profibus network caused where there were multiple masters. I think it was something to do with the different start-up times of each master and then each one trying to handle changes to "its" network as other masters woke up and started to occupy time on the network. Previously healthy slaves would suddenly be detected as temporarily faulty because the token rotation time had been extended for a few scans. I'm sorry, but what I don't remember is how the issue was cured! It was one of these situations when many parts of the installation were being changed at the same time for other reasons as well and somehow all the issues seemed to go away. Not good diagnostic procedure, I know, but that's all I recall.

Ken

GHORT, can you provide much more details, especially about the network layout.
How is the token rotation time calculated ?

Maybe the solution to Kens problem is/was to integrate everything into the same STEP7 project. I suspect that if something works most of the time but not all of the time, then it can be because the token rotation time is incorrectly calculated.

Some tweaks are possible, but we need to know more.