This White Paper on Intro to the Two Wire Transmitters and the 4-20mA Current Loop is kindly provided by our friends Acromag. Contact us for any Acromag product query.
In two-wire 4-20mA control loops, we use 2-wire transmitters to convert various process signals. Process Signals such as representing flow, speed, position, level, temperature, pressure, strain, pH, etc., to 4-20mA DC for the purpose of transmitting the signal over some distance with little or no loss of signal.
This paper reviews the operation of this transmission standard and its advantages. In particular, as it relates to the transmitter and the associated 4-20mA current loop.