If you use the raw data count from the card you could simply do the following.
4095 - (Analog Value )
4 - 20 mA = 0 - 4095 counts so...
4095-20mA(4095) = 0(4 mA o/p)
4095 - 4 ma(0) - 4095 (20 mA)
Copy the result to your AO point.
Anyone familiar with Foxboro / Invensys SCD 2100 RTU's.
I am programming using Isagraph but cannot find any information on raw data from the analog modules.
FYI It is a MX2 Mixed IO Board.
The vendor is not responding to any of my requests.
I need to scale an AI and map to some modbus...