contacts and coils

[atmoha]

hi every one can some one explain to me what are the physical representation of the contacts and coils in PLC? i think that contacts are TRANSISTORS is that true? thx

[Crossbow]

No, that is not true. Contacts can be coded for input switches, photoelectric sensors, all kinds of devices. I'm not sure what you mean by the 'physical representation'.

[atmoha]

i meant what the real definition of a contact in PLC programming..when you code this in your ladder program how it will be represented inside the PLC?

[ianbuckley]

The states of contacts and coils are stored in memory. Memory is essentially a flip-flop circuit or latch (more than one transistor). Is that what you are asking?

[Crossbow]

It's a zero or one for true or false...

[atmoha]

yes that it thx regards