It would help greatly to know the make/model of the PLC in mind!
Plus input module.

 

If the sensor and PLC share a common ground seems like a simple transistor inverter should work.
View attachment 282465

Dear Sir,
Thats a great circuit but there is a problem. There is no voltage from the PLC. The circuit I need has to supply
the 24vdc.
Thanks again.

JM

 

There is no voltage from the PLC. The circuit I need has to supply
the 24vdc.

Add R2.

 

What is the source of the "0"? And what voltage does it have when it is not zero?? Are you able to edit the program on the PLC? Is there a 24 volt source available?
There are quite a few simple ways to achieve what is asked, but just asking that without any of the surrounding information is quite useless, really it is.
If that zero is an open switch to common, then the very simple thing will be to add a pull-up to 24 volts resistor.

That is all the advice you get until the questions are answered.

Thanks for the reply. I don't have the answer. All I was told is the circuit needs 24vdc when it senses paper instead
of 0 when it senses paper. The problem is they can't get the correct sensor so there trying to make this one work.
Thanks,

JM

 

Here's another version.

 

Add R2.
View attachment 282487

Thanks so much for your help.

 

REALLY!! We are not told anything about either the source of the voltage signal or the type of input. Is it sinking or sourcing or just voltage sensitive? Nor are we informed about the signal, is it a switch to ground? Or switched to +24 volts? or switched between the two? three quite different possible formats. And the ways to deal with them are different.

 

If the switching source can source 20 milliamps then possibly a resistive opto-relay can be assembled so the +24 lights up LEDs and pulls the input low with a resistive type photocell, and when the switch output is low the input would be pulled up to 24 by a pullup resistor.

 

If the switching source can source 20 milliamps..........

Sounds a bit complicated.
The TS stated in post #22 "There is no voltage from the PLC. The circuit I need has to supply the 24vdc."
My circuit in post #25 should be all that is needed.

 

Would the PLC need a pullup, meaning could it be programmed into the PLC?

The PLC input by itself does not need a pull-up resistor. But the sensor, as described by the OP, does. Should the pull up resistor be internal to the sensor the external one wouldn't be required.

Nandu.

 

Thanks for the reply. I don't have the answer. All I was told is the circuit needs 24vdc when it senses paper instead
of 0 when it senses paper. The problem is they can't get the correct sensor so there trying to make this one work.
Thanks,

JM

Who wrote/maintains the code in the PLC?

 

Thats a great circuit but there is a problem. There is no voltage from the PLC. The circuit I need has to supply
the 24vdc.
Thanks again.

Is that simply because the input is sink input instead of source?
If so no extra circuit needed.
Again, PLC input module details would help!!

 

It seems that the TS is also burdened by a lack of information.
If the sensor information is available it may be possible to suggest a work-around connection that will solve the problem.
And that "four terminal" option i suggested is not complex or complicated, but it certainly demands an understanding of how it works.

 

Thanks so much for your help.

The NPN version will work but it needs to sink at least .1A @24VDC. The circuit I built only sinks approximately 5ma. Is
there a circuit I can build that would meet these requirements?
Thanks in advance for your time and help.

Jeff.M

 

The NPN version will work but it needs to sink at least .1A @24VDC. The circuit I built only sinks approximately 5ma.

Can you post your circuit to verify?
I think it would be better to use the PNP version I posted in #25.

 

Can you post your circuit to verify?
I think you would be better to use the PNP version I posted in #25.

 

That is the circuit I used and when the input switched to 24
vdc the input to the PLC wouldn't go below 12.8vdc.
Thanks again,

Jeff M.

 

I'm confused, which circuit shown below did you use the NPN or the PNP version?

 

I'm confused, which circuit shown below did you use the NPN or the PNP version?
View attachment 283155

I used the PNP version.
Thanks

 

Try adding R2 and R3.