Trouble with a AB IN4 analog card

[escski 0]

I'm having a problem with a NI4 analog card. I am reading a 0-10v analog voltage coming off of a Process Meter (Newport INFCPo) and after 12hrs or so the NI4 0 channel no longer functions I'm reading 0 off that channel I change to a different channel and it works for a while then the same thing happens.....the analog voltage coming in to the card comes from a process Meter (Newport INFCPO) which has a analog output of 0-10 volts and that's still remains operational , I' don't know if its the meter of if I have a defective NI4 card.... If someone has any experience with this type of problem I would appreciate your help.......thanks

[Ken Roach 194]

Are you still able to measure a voltage ( with a meter ) at the input terminal of the 1746-NI4 module that has "stopped working" ? When a channel on the 1746-NI4 stops working, does it remain failed forever or does a power cycle or reset of the controller make it work again ?

[jstolaruk 9]

Also, what are you doing with unused analog inputs? I believe you are to short them to ground (possibly with a resistor to restrict input bias currents). I recall having a similar incident as yours many years ago and I thought that a floating unused input had given us some grief before we terminated it.

[escski 0]

Ken R. ...... Yes I can still see the proportional voltage coming into the damaged analog channel and the two damaged channels remain even if I reset the PLC. Jstolaruk : I left the unused inputs floating... I have 2 good channels left ...I have moved to one of the remaining good channels and grounded the rest.... the Machine has been running now for about 24hrs....I think that was my problem.. Thanks Guys ...I really appreciate all your help.....Product was begining to pile up....you guy got my manager off my back ......many thanks.....