GE 90-30 CPU374 and Cognex Cameras

[Chris Elston]

Hey guys/gals, I am just about ready to roll out another big GE project. I have some serious questions about communicating with Cognex cameras. I will have a series of Cognex cameras on this system running on Ethernet. I need to know how to communicate with a Cognex Camera using a GE 90-30 CPU 374. Or maybe I need something else to do it right. Like an Ethernet IP master card or something. I've done this in the past using an Allen Bradley processor with an ethernet port (without an Ethernet IP master, direct using a Message Instruction) I don't see any support or functions in GE 90-30 for ethernet messaging. Here is a whitepaper that explains the connection to an Allen Bradley CPU. http://forums.mrplc.com/index.php?autocom=downloads&showfile=429 Does GE have a whitepaper? Has anyone done this yet?

[Steve Bailey]

Does Cognex support any protocols other than Ethernet IP? GE Fanuc's preferred method is what they call Ethernet Global Data, but they also support Modbus TCP. I'm not sure about whether the CPU374 can handle ModbusTCP though. You may need to use an ethernet module (IC693CMM321) in the rack.

[Chris Elston]

Under networking at Cognex, it mentions Modbus TCP. http://www.cognex.com/products/InSight/Networking.asp I am trying to confirm this. I also need to confirm if the 374 can talk Modbus TCP I/P without using the CMM321 ethernet card in the rack. I created a ticket in my GE global support. I got a call back within 5 minutes from a GE support guy that was very knowledgeable about Cognex and GE 90-30. He recommended using the Cognex Device Net gateway (I didn't even know they made one) and a GE 90-30 DeviceNet master card. He said it's been done in the past and it works. (I thought he said) that the 374 supports Modbus TCP I/P but could not confirm if it can message or do a "Comm Req" to a Cognex camera. I am pretty sure from the Cognex website they support Modbus TCP I/P, however this support guy couldn't commit that it actually worked because he hasn't set it up, nor does he know it's been tested. I was thinking about testing this on my own. I know this is against GE's recommendation but it would save us a TON of money and worth a look if we can get the Modbus communications working. I would rather put the devicenet method as plan "B" at this point, and think it merits a look at if we can get Modbus working. If Modbus works, we don't need any additional hardware to make it work. Just an ethernet switch, which we already have anyway to network the cameras and PLCs. -

[Steve Bailey]

Everything I can find seems to indicate that you will need the CMM321 module to do Modbus TCP communications as client (initiator of communications). I can find a reference in the release notes for the CPU364 (GFK-1875) about setting up COMREQ instructions for ethernet communications through the port on the CPU, but it doesn't say anything about Modbus TCP, only that you can do SRTP (GE's SNP protocol over TCP/IP ethernet). Furthermore, the release notes for the CPU374 (GFK-2123*) lists "COMREQs for ethernet messages" among the CPU364 features not supported on the CPU374. However, there is supposed to be a CPU374 PLUS being touted as the replacement for the discontinued CPU364. See this thread: http://gefanuc.bnsi.net/eforum/showthread.php?threadid=5705 You may want to start a thread on the subject over at the GE Fanuc forum.

[Chris Elston]

Thank you very much for this information. I think I see what I am up against now. I will keep picking on the brains of GE Support. They seem very responsive today I am such a happy camper!

[RussB]

Neither the CPU364, 374 nor the new 374 support Modbus TCP/IP right now. The CPU374 (new enhanced version) is scheduled to have it added in a future release. You can use the CMM321 as Steve indicated, we have done this with the Banner Vision Sensor so it should work with Cognex. It should work as well with Devicenet, but there are advantages to having everything on the same wire.