NPN Inputs??

Good day everyone, I am new to the site so go easy on me, haha. I have a Siemens Simatic S7-400 PLC, I also have an Omron E3S-BD61 General Purpose Photoelectric Sensor which is NPN, my question is will the digital input card (421-1BL00-0AA0) accept a NPN input or will I have to go through a relay to achieve it??

Not directly, it is possible to use a resistor from 24v supply to the input (and signal of Prox) this gives you an inverse logic.
the NPN when de-energised will feed the plc input via the resistor
when energised the NPN of the prox will pull the input to ground so the resistor needs to be selected to allow a nom 10ma for the plc input + a little for the prox, so a 2K should do it.

Hi Guys, I am currently trying to use an PNP 3 wire sensor to PLC with sourcing inputs.

After looking at a few threads, I realised I could use a resistor for that purpose, without performance penalties.

Can I confirm that for PNP to be used with sourcing PLC inputs, I have to connect the sensor output (also to PLC Input) to one end of a 2.2K resistor, and the other end of the resistor to 0VDC?

Would the signal become inverted? as in it becomes normally closed, and opens when it senses?

Thanks!

Phoenix Contact have very inexpensive converters that will do the conversion both ways. Looks a heck of a lot more professional than a resistor hanging out of terminals.

... needs to be selected to allow a nom 10ma for the plc input ...

I believe the input card will draw about 10 mA if connected directly to +24. The resistor will protect the transistor when energized (low signal to PLC) at the expense of lowering the ouput (signal) voltage at high signal to PLC.

Most sensors have a more or less complicated instrument (could be integrated) for signal conditioning. In this case the instrument could be just a "proffesional" looking resistor but it would probably filter the raw signal too.