sink vs source
sink vs source
(OP)
Greetings From Colorado.
Can anyone tell me the if there is seriously an advantage to sourcing IO current vs sinking it?I have an old design here at the plant that sinks(pnp)and wouldnt be that hard to change the wiring to accomodate sinking(NPN).I heard PNP is faster but noisier.
Thanks for the input
Montech
Can anyone tell me the if there is seriously an advantage to sourcing IO current vs sinking it?I have an old design here at the plant that sinks(pnp)and wouldnt be that hard to change the wiring to accomodate sinking(NPN).I heard PNP is faster but noisier.
Thanks for the input
Montech





RE: sink vs source
PLC inputs that are referenced to ground are usually easier to deal with.
I see no reason to change from one method to the other if it's working.
Roy
RE: sink vs source
Keith Cress
kcress - http://www.flaminsystems.com
RE: sink vs source
Happy coding!
Montech
RE: sink vs source
Most PLC manufacturers usually only produce dc input card where it is looking for 24vdc or sourcing outputs and inputs. If you look at lead times it is hard to get any quantities for sinking or npn type cards. Most PLC manufacturers have sourcing or PNP type cards on the shelf.
RE: sink vs source
RE: sink vs source
The first one is that it is more fail-safe to have a signal that doesnt turn into a True signal when the wire is shorted to GND, which was almost universally the case with old sinking (NPN) I/O.
The second reason is that it has been a safety standard to use nothing but sourcing I/O for longer than I can remember. There is even a standard prescribing sourcing I/O in machine tools and some other equipment. I have forgotten that number, too. It is so taken for granted that no one remembers there is a standard any more.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
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(I enjoyed the input statement by the way)
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