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pattyo

CP1H networking issues

8 posts in this topic

Hey guys, First I want to thank you for the support in the past. We have our machine up and running and have hooked it into our company network in order to collect SPC. We have the PLC running so it can be standalone, but also have a PC running XP attached for a Visual Basic user interface. We basically store SPC in an access database on the network. The first problem we had was when we connected the PLC and the computer to the network, the PLC software would keep crashing. When doing nothing, the activity light on the ethernet module was blinking. We think the PLC was receiving too much network traffic and being overloaded, even though I thought ethernet protocol shouldn't really let this happen. In order to fix this, we isolated the PLC from the network by installing another network card in the PC and put it on a different subnet. Now we have the issue that the PC is extremely slow when accessing the network. The VB software is laggy and even doing simple windows explorer tasks are very very slow. How the heck do big companies set up their PC/PLC/Network with many machines? We are clearly doing something wrong. Any guidance is appreciated.

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Specifically what do you mean "the PLC software would keep crashing"???? Does the PLC stop operating or do you lose the communications with it??? Which Ethernet module are you using on the CP1H??? The fact that moving the Ethernet connection to a different adapter on the PC changed the symptoms leads me to suspect that your problem is related to your network configuration.

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Sorry, I said that part completely wrong. What I meant to say was the PLC and PC would lose connection. The data being updated on the user interface would freeze frequently and sometimes not update at all. We are using the CIF41 ethernet option board. This very well could be a network configuration issue. Unfortunately, our IT guy can't figure it out and I don't know enough about it to fix it.

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Without knowing all the details of your network setup it would be impossible to solve your problem. It does appear that what you have done so far isolates the problem to an issue between your PC and your network rather than a PLC problem. As far as alternative methods, I normally use a touchscreen with data logging capability to capture data from PLCs and upload the data file from the touchscreen on a scheduled basis.

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I think the CIF41 cannot handle the client's polling rate... It is not a "full blown" ethernet module and has a limited framesize of about 1000 bytes I believe. You should look up the CIF41 specs and make sure the client is designed to poll within the througput limitation.

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Quite possible. It is just a serial to ethernet converter after all and thus limited to serial speeds (as well as the frame size limitation).

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The other issue that I have seen is that the CP1W-CIF41 does not handle all of the other network traffic (Rapid Tree Spanning, Tree Spanning, etc) very well. Isolating the PLC removes all of the other 'IT' traffic from the PLC, and lets the CIF41 focus on what it was designed for: FINS communciations.

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So perhaps would a CJ1W-EIP21 (Shielded twisted-pair cable (STP), category 5 or 5e or higher. Tag data links and message communications supported) a better option if we wanted to integrate directly to our LAN? I can find out more information about our network configuration if that would help. Thanks for the input thus far.

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