What are the two categories of Instrument transmitters?

Two categories of Instrument Transmitters are

1.Loop-powered 2.Non-Loop powered

Loop Powered

2 wire connection supplying both power and communication Power is supplied over the current loop from the control room Entire transmitter must operate on <3.2 mA for a standard transmitter and <2.7 mA for a HART enabled transmitter.

Non-Loop powered

4 wire connection,two for power and two for communication No power consumption limitations Used in situations where sufficient power cannot be derived from the current loop.