AI-111 Channels are starting to read low or not at all

[plow]

I have several fieldpoint modules connected together, one of them is an FP-AI-111. This module is reading in only 4 different instruments, a flow meter, and three pressure transducers. I have had the setup working well for the past month and a bit then suddenly a few days ago the channel which my flow meter was hooked up to went out of range high, but when measuring on teh flow meter itself it was outputing 4mA. LAter disconnected the flow meter and the channel was still reading an over range condition. I had lots of spare channels so simply moved my input channel. A few days later one of my pressure trasnducers started to read low and found that on MAX the pinput current was reading lower now than what the instrument was outputing (diagnosed instrument with HART). So again moved the channel and on the new channel it is reading fine. Now a thrid instrument is having the same issue and again will move it to a new channel. But this does not give me great confidence in the readings now.

All instruments are loop powered and are supplied with 24VDC on the Vsup. Nothing changed to the setup to start this cascading downgrade on my input channels. Has anyone ever experienced this issue with FP-AI-111's before? 

[Smootastic]

Hi plow,

How long have you had these modules?  Do you have any replacement or similar modules to test the measurements with?  Does supplying a known signal to the ai-111 measure correctly? 

[plow]

I have had these modules for about a year, we got them second hand off a company liquidating some of their equipment.

I don't have another AI-111 to test out. 

I did use a Fluke process calibrator on the channels and found that when inputing a curretn of 4mA it would read about 5.8mA and with 20mA it owuld read 18.4mA. 9mA was the point where it would read equal to what the process calibrator was sending out. 

Found that this reading was very similar across most of the channels of the module.

[Smootastic]

Hi Plow,

It sounds like the AI-111 may need to be calibrated.  You can find information on this at http://www.ni.com/calibration