Analog input not showing true indication

I have a Ktek level meter, AT26. Yesterday, for some odd reason, the meter failed - as in, no longer shows the proper level. To date, I have changed the transmitter, the analog card (1756-IF16), and the fuse holder just for luck.

voltage = 24V.
current in runs the full range of the 4-20ma scale.
scaling for the meter is 60"
PLC scaling is 12-72"
Simulating an input at the PLC shows the true reading (12-72") for 4-20ma

No matter what I do, I can't get a reading of over 18". I can't figure out how I am losing the signal. I measured voltages at the terminal strip, getting the same thing as another meter right next to it. I'm thinking a voltage problem, but it all seems to check out.

One possibility is the ranging is reversed, but still, with 19ma in, I expect something on the PLC toward the high end.

I'm confused. Any ideas?

Sounds to me like you've eliminated about all possible culprits except the wiring between the instrument and the PLC. Have you tested the copper at all? A corroded connection could certainly limit the current flow.

Bill

Yeah that's a thought. There's lots of wiring between hither and yon. I'm still confused about getting full scale at the terminal strip; it could be a voltage problem with the wiring even though it all "looks good". I'll check.

Bad, apparently "very sensitive" terminal strip on back of transmitter, had a spot of corrosion on it. Replaced it and all was well. Yuk.