I am at the end of ideas. I know I am grabbing at straws here but I dont have enough PLC programming experience to rule it out. So I gotta ask. Using iFix4.0 and 5.0 for HMI, GE OPC and ABR drivers through RSLinx 2.51, 2.54 to PLC5,1 SLC , CompactLogix and ControlLogix PLCs. I have intermittent but frequent connection losses to multiple PLCs around the plant causing the HMI screens to show ??? in place of the data. So far they clear thmeselves up in just a few seconds but this is only getting worse. The OPC driver in every machine will show errors similar to this: AB_ETH-1\0.(10.10.28.17).1.0 : F07_Air_Alarm_Reset : 03/13/09 - 20:01:44 : 00h Items: F07_Air_Alarm_Reset Type: READ Mfg: Allen-Bradley PlcType: Logix5000 Desc: ControlLogix Optimized packet being reinitialized 74bf620, connection 4813329, packet's connection 4813329, packet's read connection 0, packet's state --Creating Optimized Packet - and - Desc: CIP Messaging Error: a message timed out waiting for a response -and- AB_ETH-1\0.(10.10.28.42).1.0 : @IsPresent : 03/13/09 - 21:01:09 : EE00036h Items: @IsPresent Type: READ Mfg: Allen-Bradley PlcType: Logix5000 Desc: Control Net Service cannot be performed while Object is in current state Number of occurrences: 20 Last Error occurred: 03/23/09 - 07:15:18 - and I just love this one - Desc: A Timeout occurred where the engine didn't generate a timeout in the time required. Every single SCADA does this so I can't imagine out how it could be a configuration issue on a SCADA. Even a machine I purposefully havent touched for a year does this. I really thought it was RSlinx but how could this happen on so many machines like this and what could cause it? I examined the HTTP interface to the PLCs and their CPU's are running at about 5%. There are ZERO errors in the Ethernet Statistics. So I spent the entire afternoon with my Packet Sniffer at each PLC in question and at one of the SCADA servers. All I found (and fixed) was a single HDX port mismatch on the switch but that port isn't even in the PLC circuit. I examined the managed switch through which everything flows and it has no errors noted. I am going to borrow one and replace it as a test but I am not hopeful. I can see nothing wrong with the Ethernet layer, I think I saw 2 TCP retransmits, a bunch of immediatly answered keep alives but nothing else. I'm truly stumped. So the question becomes; Since it appears that all traffic that actually gets generated is being properly handled, Is there anything within a CLX program that can make RSLinx or a single or multiple PLC's stop responding like this? Something like a program sending a message to itself that would consume all the CPU resources until it failed, yet have no external traffic? (told ya, straws!) I welcome ALL ideas, I got none left.
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