4-20ma customer PLC supplied signal for monitoring (XC43)

mgoutier 3 years ago updated by Gustav Widén (System support) 3 years ago 2

I am designing a new system where the customer has to send me a 2 wire 4-20ma signal to monitor. I can add a resistor to convert it to a voltage input, but I would prefer not to. The manual shows a 3 wire hook up, if I were to not use the Vref pin, would this still work? I am not concerned about the output getting out of scale, and when we do a startup I can calibrate it to the PLC actual range... 

Should this work?

I guess my question is a bit off, the manual shows a 2 wire signal, but it is assuming that the module is sharing the same power as the sensor. 

On this system, the power source is not shared... 

So could I use this method to use this signal? I am assuming not. 

"Using current inputs to monitor voltage inputs
Another use for current inputs is for error monitoring of analogue voltage inputs."

Not sure if I understood the question. 

But the CIN channel on the XC43 does not have to share the same ground as the device that generate the 4-20 mA signl, its current measurement is done across a resistor.