Communication loss

Hello all,

I'm experiencing some communication problems with my project.

I have a WinCC server, 3 Clients, an S7-315 PLC.

Each 3 seconds I get a pulse from the PLC, on this pulse I'm supposed to do some actions in a separate SQL database.

I already removed all database related stuff and stripped my project down to just interaction with a PLC tag and the diagnostics screen.

In my PLC I also count all transactions, and there I have nog loss. But from time to time my WinCC acts as if it doesn't see the bit coming in, so the numbers don't match.

I also spoke a colleague, he suggested to work with a FIFO in the PLC and pass to me every 5 pulses the information, so I have more time.

Could this be something in my configuration that WinCC doesn't see the signal fast enough ?

I use S7 protocol suit connection, type is TCP/IP

The global script that starts to do things is triggered on change of my PLC tag.

Also, one more thing to add, due to circumstances I was obliged to use a S7-lean card, there was no more space inside the electrical cabinet. Me, me colleague, the server are working on this PLC one way or another, maybe this is the cause ?

Please advice,

Tom