The difference between independent power supply, loop power supply and output circuit power supply?

Independent power supply refers to the need for individual 24V power supply.

Loop power supply: there is no need to supply power individually, and the power and signal are in the same loop.

Output Circuit Power Supply: This situation is slightly more complicated. It is "independent power supply", but the output part is "circuit power supply", that is, the output is passive signal, which requires PLC/DCS to provide power.

Generally, the automatic control system uses independent power supply, the input can be passive or active signal, and the output can be active signal.