Level logic

[dandrade]

Objective know which the level logic frequently common.

Vote and specify the brand and Model PLC, avoiding repeat.

If the PLC have levels logic (digital) not equal for set input high speed counter or interruption, vote option 07.
Or levels adds, case will not be in the list.

Also it can insert problems that occurs due to the levels logics. Component or class of sensors that are little compatible.

 

[CaseyK]

I'm not sure I understand your question clearly enough.

Are you looking for the common voltage states for the inputs when they are logic high (ON) and logic low (OFF)?

regards.....casey

 

[dandrade]

Yes,kc9ih correct is simple question.

Detail that generates problems with disgusts and long delay

The leds of INPUT can be lightened and do not represent the state ON.
Potential factor for the electricians will accuse that the software does not operate.

...by this, the importance

 

[CaseyK]

Normally, I see no more then 2-3 volts in the off stage, if that much. We often use a R-C network for spike suppression, which probably helps.

I have turned down supply voltage on an input from 24 to 5 volts without dropping the input. Depending on brand, I have made the input high with voltages sometimes under 10 volts, ONLY on some units. I don't think that there is any consistancy.

With AC 120v inputs, I've seen a wide range too.

Regards.....casey

PS - Do you use the translate feature on here?

If so, how does it work?

 

[CaseyK]

Don't remember if I have ever seen the input LED on, with the input not actually being on.

I suppose that this is possible with some brands of plc's.

I could see where it could happen on some smaller moe inexpensive brands, that utilize fewer components.

I would not expect to see it on Allen Bradley, GE Fanuc, Siemens, or any other big name. I would expect theie input LED to be driven from the input circuit AFTER it has been processed.



ANYONE out there seen input LED's lit, without the input circuit fired or program recognizing it? This would be from a floating voltage of several volts lighting the LED but not reaching the threshold to turn on the plc.

this could be caused by internal leakage, or from the external components to the input circuit.

regards.....casey