software relay

hi friends. can any one tell me whether plc uses software or hardware relay on its output terminal. if it is software relay then how does it work.

Depends on the hardware you buy. both are available

Hardware relay on an output terminal. Always.

You can't connect software to a physical terminal.

Relay implies physical isolation which triac outputs with a common voltage supply do not have.

True software never translates directly into hardware but there are varying degrees of isolation.

Nope. The difference that you are explaining, is "Solid State" output versus "Relay Output". Both are hardware.

There is no physical 'Software' output, ever.

The only 'software' outputs are internal coils in a processor's memory. The OP may have misphrased their question, but that is the one I've answered

True

Obviously software can't directly act on the real world. A PLC discrete output uses an internal software "relay" to operate the output hardware that is connected to the terminals. This discrete output hardware connects the load to a voltage source and physically turns on the load. The discrete output hardware may be an actual relay, a transistor, or a triac.

Mayhap, you would like to read what goes on inside the PLC device. It will cover some things related to what you are asking.:nodi:

But my answer is: a PLC output always connects to hardware devices, no matter it be relays, terminals, display devices..etc. But before the signals goes to the physical output, it is being processed inside its brain, the CPU. In there, are lots of "software" relays and output coils are makes up the its basic functions. Just like how a human brain works...nerves sends signals to the brain, and the brain processes the signals with the help of nurons (can't remember the spelling), i.e the internal relays and memory coils; and then to the physical output, which is your reaction (output) to what you had experienced (input).

Am I making a lot of repeating here?

regards
Sherine T.