Problem in getting accurate measurement using NI 9227

[Deepa_Krishnamurthy]

Yes I did try and I tried again today

Floating : values were 0,2 r 0.1mA lesser in A0, A1, A3. A2 had 0.8-0.9mA difference.

when grounded: the channels A0, A1, A3 gave exact values. But, at channel A2 1mA lesser output

[Henrik_Volkers]

What happens if you swap channel A2 sensor (Source)  with A1?

[CFER_STS]

It is possible that a ground loop is to blame.  This is why your power supplies should be part of your wiring schematic.  Are the four devices which produce the 4-20 mA DC all powered directly by the AC mains? Or do you have DC power supplies? Access to the DC power rails if not? How are you supplying DC to the the cDAQ 9185? The power supply common rail should be common between the cDAQ and the current sources if possible.

I concur with the suggestion to swap the sources on channel 1 and 2 to see if it is the source that is the problem, or the cDAQ 9185 / NI 9227.

Also, check the specifications on the multimeter you are using to compare against.  It is also possible that the NI 9227 is the more accurate device.