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4-20ma Input to a VIN using a 250 ohm resistor

Barnhart Crane 3 years ago updated by Gustav Widén (System support) 3 years ago 1

Has anyone had any luck using 4-20ma sensors to a VIN using a 250 ohm resistor to convert the signal 1 to 5 volts?


It seems to me that this is a good option since most IQAN modules (except MC4X series) don't have current loop inputs, but I haven't tried this yet. Obviously using a low tolerance resistor would help, but would doing this take any of the benefit away of using a 4-20ma signal in the first place?

+1

If you are able to source a 0.5 to 4.5V sensor, that should be better. 


In some cases where this was not possible, I have advised a 120 Ω pull down (e.g.PN 5030083) for use with 4..20 mA  sensors 

=> 0.48 to 2.40 V on the VIN input

With a 250 ohm resistor that gives you 1-5 V, you would read 5 V regardless of sensor output in case you get an open circuit on the external pull-down resistor.