PLC 5 1771 - IFE Trouble

Hi, currently have an series A IFE module in PLC 5 chassis. Running fine for years. Last week starting getting erratic data from all channels (only using 3 channels). Swapped card, power supply nothing works. Funny thing is, if only 1 channel hooked up data is correct for that channel, when hooking another channel up, all data starts to go erratic? Nothing has changed in our process.

The new card you put in, is it a series "A"? Did you check all the jumpers on the new card to match the old?

Yes, I made sure all switches are correct. Don't think it's a card problem, both new and old cards act the same. Could it be a backplane problem? Noise? Interference from another card?

Thanks

It could be a grounding/shielding problem from connected transmitters.

Short answer, yes. Do you have a way to test the cards in another system or test chassis? Thus eliminating the cards as the problem.

All unused channels are jumpered out and cable shields are grounded. Nothing has changed for years?
Thanks

Our production process is 24 hours a day. Only time is on weekend, which I plan to do more testing. Would appreciate any more ideas which I could try now or when production stops for the weekend. I will move card to another chassis to see if problem follows.
Thanks again.

Make sure the transmitters are only shielded/grounded at one end (at power supply point).

If you are using differential analog inputs your problem is more difficult than using single ended inputs

Try to avoid mixing voltage and current signals on the same card unless you can tie the commons very tightly to one end of the same power supply

In fact the only analog inputs that I have difficulty with are differential inputs that cannot, and never will work as single ended inputs, boss won't buy isolators for each channel so I live with the noise and try to develop methods to minimise it

try reading you may need a tech connect contract to sign in to see this one
http://rockwellautomation.custhelp.com/app/answers/detail/a_id/14088/kw/1771 ife noise/r_id/113025

Try reading this manual
Chapter 7
http://literature.rockwellautomation.com/idc/groups/literature/documents/um/1771-um663_-en-p.pdf