Hello everyone, I'm using Applicom's IE TCPIP OPC Server V3.5/OPC Client to access data blocks (DB) words from an S7-300 PLC (CPU315-2DP V1.2) via a CP343-1 V2.0 (TCP/IP Interface) module. Utilizing a network monitoring program, I have found the device turnaround time to be consistently 30ms. I've played with the CPU settings "Scan Cycle Load from Communication" and "Scan Cycle Monitoring Time" and have found that they do play a role in this time. Regardless, i cannot get the turnaround time to better the high-20s. Does anyone know of any other settings that may play a role in communications performance? Are there any settings in the Applicom OPC Server that may have an effect on this? I've tried INAT and Simatic NET's OPC Server but obtained the same results. 30ms is just unacceptable for my customer. Any help would be greatly appreciated.

Thanks in advance,
Richard Sanchez

 

Richard,
Using a S7-300 offer such performance. This kind of PLC reply to a request at each cycle time (you cannot go faster). That means that, if your time cycle is 100 ms, the request will be answered after 100 ms. If the scan cycle is 5 ms then, you will reach the maximal performance of your CP (30 ms).

Only S7-400 can be asynchronous to the PLC scan time, but unfortunately, even if the time to answer is constant (does nor depend on the scan cycle) the measure we made were about 30 ms.