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skjomcs

Kepware/OPC Networking L3

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hi came across a network which used Kepware to collect information from a number of PLC's. some PLC's reside on the network 10.x.x.x these communicate okay with the kepware server which resides on 10.0.0.1 There are then a number of switches which were sitting on a L2 switch on the 192.x.x.x network- these could communicate with the server on 10.0.0.1 when an alternate ip in the 192.x.x.x range was added to the server- however it was noticed that the traffic through the network caused an issued with the PLC, the local ethernet switch was receiving a lot of broadcast traffic from all the 10.x.x.x devices (some were business networked PC's.) We substituted the L2 switch for a L3 switch and created two VLANS on the L3switch , the server was connected to vlan 1 (10.x.x.x vlan), the plc's were connected to vlan 20 (192.x.x.x) and inter vlan routing established on the Layer 3 switch. The issue with the PLC was resolved (it was sending go/nogo signal to device downstream) the server (now only has a 10.x.x.x ) address can ping the PLCS on the other vlan (192.x.x.x), however the Kepware software cannot access the tags on the PLC it needs to read. Can OPC be routed like this? or can someone point me in the correct direction. Thanks

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Shouldn't be a problem. Check that the Kepware server uses the correct interface and not any obsolete physical interfaces. If you can ping the PLC's Kepware should indeed be able to communicate. Do you have any other software on the server that can be used for testing comm except from cmd and Kepware to check if it's just Kepware failing, or just ping working?

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okay thanks when you say correct interface what do you mean? i was thinking of installing wireshark on the server and watching the communication or also transferring a file to a pc on the vlan to make sure something other than a ping works. found this online: www.opcdatahub.com/Download/PDF_Release/OPC%20DataHub%20-%20Tunnelling.pdf "But networking OPC is challenging. The networking protocol for OPC is DCOM, which was not designed for industrial real-time data transfer. DCOM is difficult to configure, responds poorly to network breaks, and has serious security flaws. Using DCOM between different LANs, such as connecting between manufacturing and corporate LANs, is sometimes impossible to configure"

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I was just wondering if Kepware had any kind of approve-list or table that indicated which physical interface to use for the different PLC's, so when you now have removed (or just disconnected) one physical interface, do Kepware still expect the communication to go through the old physical interface, or will it allow for it via the "new" routed interface? All in all; as long as your peripheral PLC's has a configurable gateway or router you should be good to go!

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OPC is what an OPC Client uses to communicate to an OPC Server. It is straight device communications to the PLC's. You should be able to talk to any device as long as the Subnet allows the addresses and routing is enabled via the switch. That is what should be checked in this configuration. You can also contact Kepware for additional help.

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