Analog Signal

4-20mA is used because it's convenient, provides good noise and disconnection immunity and for historical reasons.
Applications? All and any.
Del

Thnks,but can u say the PLC related application.

Any analogue measuring application in any process, say measuring ph in water treatment. The reading can then be used to control whatever is necessary to maintain the correct limits..

ok thnks dude

I would never use such language, for venerable Del the cat

For PLCs, 4-20mA is probably still the most common input option for analog data. (Some PLC mfrs do offer specialized RTD or thermocouple input modules, and various other signal protocols.)

this is the most common input (4-20ma or 0-10v)

the applications are pressure transducers and thermocouples also its common in

flow.

...plus the use of a 'live zero' of 4mA means that readings below this can be used to provide an instrument fault alarm at some central control console.