Usage of FB 125 DP Diagnostics

Hi to all

I have a PROFIBUS-DP network with ten nodes. I need to make a diagnostic of every node and to generate a "communication alarm"in the Step 7 program for every node.
There are some problems on the network, like very fast drop of the communication between some nodes, so I need to know which nodes are not responding. The drop of communication are very fast so I need to keep trace of the event so Ihave to generate an alarm for the nodes not responding, which I can found after the event verification.
I want to use the FB125.
I called the FB125 in OB1,OB82,OB86 but I have some troubles:
If I use it in automatic mode I can't know which nodes are down in the case of there are more than 1 node in alarm.
If I use it in manual mode: at every second I increase the address of the node to investigate, make the diagnostic of the node andevaulate the comm. alarm. In this case the problem is that if the errorof one node comes while I am investigating another nodeI lose the event!

Suggestions?

Thanks a lot in advance.