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I am using a Kepware OPC server to interface an Intellution SCADA system to 2 Siemens S7-200 PLCs through their CP243-1 modules. The Siemens PLCs were supplied by someone else and I'm not to familiar with them but the ethernet setup looks pretty straight forward. The problem I am having is they will communicate for a day to a week and then one of the processors loses communications to the Kepware driver. It's not always the same processor and it's very intermittent so I can't nail down what is going on.
When communications is lost the Kepware driver appears to be polling and getting failed reads. Its error is "Device Not Responding". It's as though the ethernet module just stops replying to the polls. I changed my poll times down to about 1 poll every 10 seconds to make sure I'm not overwhelming the modules but it didn't have any affect. Cycling power to the failed Siemens PLC usually immediately reestablishes communications. Both PLCs are set up the same with one configured connection. There is only one computer on the ethernet network. Both PLCs have the same TSAP addresses but different IP addresses. Could the same TSAP addresses be causing an intemittent problem?
There are Allen Bradley devices in the same system connected through the same ethernet switch and network hardware so I don't think its a network problem. The PLCs appear to be running a lot of logic. They are also communicating RS485 and profibus to other devices. Could they be overload or are there settings in the PLC which need adjusting? If anyone has had any experience with these PLCs help would be greatly appreciated.
When communications is lost the Kepware driver appears to be polling and getting failed reads. Its error is "Device Not Responding". It's as though the ethernet module just stops replying to the polls. I changed my poll times down to about 1 poll every 10 seconds to make sure I'm not overwhelming the modules but it didn't have any affect. Cycling power to the failed Siemens PLC usually immediately reestablishes communications. Both PLCs are set up the same with one configured connection. There is only one computer on the ethernet network. Both PLCs have the same TSAP addresses but different IP addresses. Could the same TSAP addresses be causing an intemittent problem?
There are Allen Bradley devices in the same system connected through the same ethernet switch and network hardware so I don't think its a network problem. The PLCs appear to be running a lot of logic. They are also communicating RS485 and profibus to other devices. Could they be overload or are there settings in the PLC which need adjusting? If anyone has had any experience with these PLCs help would be greatly appreciated.