Hello,

I am using a CS1 PLC with an ETN21 card. The card is addressed at Unit #9 and is marked as Node 31. It will work for about 2 to 3 weeks at a time and then stop sending and receiving. It gives no error just stops working. When this happens the SEND and RECEIVE lights go out and the RUN, 100M, LNK, and HOST lights stay on. If I go in and reset the card it will work fine for another few weeks. We have tried 2 cards and they act the same way. We are only using the ETN21 for remote programming purposes.

Anyone have an idea?

What is the unit communication used for?

When the unit stops communicating:
-Are you still able to access the CPU through CX-Programmer by Ethernet?
-Have you checked the unit error registers in the CIO memory and error log through CX-Programmer I/O table?

If you "go in" do you reset the card by setting the special I/O unit restart bit?

Although there is no ERR indicator on it might be worth to check.
Have you got the manual W343-E1? See section troubleshooting for memory locations.

CS/CJ Series CS1W-ETN01 (10Base-5)/CS1W-ETN11 (10Base-T)/CJ1W-ETN11 (10Base-T) Ethernet Units Operation Manual

The unit is only used for communicating with the PLC from CX-Programmer. I am unable to connect to the PLC with Programmer when it stops working I have to use the peripheral port. The restart I use is an option when you put the PLC in program mode, open the I/O table, and click restart. I will check on the memory areas when we take the line down to change some things on second shift and I will let you know.

There are no errors in the memory area.

So when it 'stops' communicating, and you try to connect with CX-Programmer, does the receive LED lit up?
Can you ping it?

See section 9: Communication testing functions.

The receive light does not come on and I cannot ping the card.

One last thing I would check is if you are not accidentally misusing the unit setup area memory in your code.
For unit #9, this is D30900 - D30999.

Can you save the setup parameters of the card and post the file?

Alright, after weeks of battling this issue it was inadverdantly solved. A few days ago we lost the monitoring of our device net. An error message in CXIntegrator that wasn't worded very well had us believing it was a setup issue. It also kept informing us that we could not connect to the card but wouldn't say why. Turns out something else was already connected and you can only be connected to one thing at a time. We selected the network adapter (puts the little lightning symbol over it) and were told by Omron tech support that this should fix our Ethernet card issue as well.

This was the explanation given to me by the engineer who figured it out. If something doesn't make sense let me know and I'll try to get him to explain it better.