Communication break down several time in day

Hi,
I was using Siemens Profibus CP5611 communication to communication with Citect in Windows 2000 Professional. The system is installed at the POWER PLANT. The distance between the PLC master and Slave is around 150 Metre and Between CPU and Scada(Citect0 is only 4 Metre.

The communication between Citect and PLC was break down frequenctly, around 10 times per day. and it take about 2 ~ 10 minute to recover back.

The version of citect is V5.41 Services Pack B and Softnet i am using is SoftNet-S7/Windows V6.0.

I was try to slow down the Communication speed from 1.8 kbs to 187.5 bps but the problem still remain.........

Anyone can give me a help on that?

I had a similar problem with communications via the S7 ethernet card.
It turned out to be the version of simatic net that I was using.
We upgraded to the latest version, and seem to be running OK.
I will try to find out which version I used.

Check with Citect, my guess is, you need Simatic Net (Softnet) Ver. 6.0 SP4. You may be running without a SP.
Check the terminations and make SURE you have terminators ON at both ends and OFF in the middle of the cable runs. You may want to try new connectors. Are you using the Siemens Profibus cable? If all else fails, upgrade the profibus card to a CP5613, it is more robust.
Softnet comes with an OPC server built-in and SCOUT is a free OPC client. If you want to check the communication between Simatic Net and the PLC, you can use SCOUT and look at the tag values, along with your HMI running. If the HMI stops communicating, check with SCOUT. This will tell you if the problem is between the computer and the PLC or between the porfibus card and the HMI.