Sourcing vs sinking

[Mark.W]

Hey Chaps

Just a quick one, how do we know when to use sourcing vs sinking I/O on a PLC?

Examples would be great please.

Many Thanks

Regards
Mark

 

[ackbarthestar]

Hey Chaps

Just a quick one, how do we know when to use sourcing vs sinking I/O on a PLC?

Examples would be great please.

Many Thanks

Regards
Mark

Here you go

What Is the Difference Between the Terms Sinking and Sourcing? - National Instruments

Most digital cct, if not all work on Low = go (0) and high = stop (1), and very high = not available

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Hey Chaps

Just a quick one, how do we know when to use sourcing vs sinking I/O on a PLC?

Examples would be great please.

Many Thanks

Regards
Mark

Here you go

http://digital.ni.com/public.nsf/allkb/A10122C63A7F5CFE86256B4C007491DD

Most digital cct, if not all work on Low = go (0) and high = stop (1), and very high = not available

 

[plugsandsparks]

Depends on the nature of the design, if its all from scratch you have more options as you can generally get devices for the plc that can switch either way. If you are replacing a plc then unless you want a real headache then you need to wire it how its wired currently.
In simple terms plcs will "see" either a high voltage condition as an input or "see" a low (o) voltage as an input.
Download any PLC manual for its wiring options and it will show you how to wire up for the two different methods.
When you order your sensors PNP/NPN make sure you get the correct ones.
I usually get it wrong but think i am a bit dyslexic

 

[newbec]

On the output side, an output that sinks current is more preferable. Especially if its a floating output, as this allows a different DC voltage, with reference to the controller voltage, to be switched as long as they are both referencing the same 0V.