TConnolly
Lifetime Supporting Member
I have several Modicon 984s using 875-002 4-20mA input cards. The sensor is a pressure transducer. When the pressure is at 0 the input word from the card tends to roll over backwards to 9999 when the input current drops just below 4.0 mA, ie 3.999 mA reads 9999. This of course creates a bogus pressure reading. To prevent this Bubba calibrates the transducer with a slight zero offset, but that means that it is no longer accurate.
Has any one else ever encountered a similar issue and how did you resolve it?
Has any one else ever encountered a similar issue and how did you resolve it?