Converting PNP output for device Expecting NPN output

ndzied1

Lifetime Supporting Member
Join Date
Aug 2002
Location
Chicago, Illinois
Posts
2,852
The subject question says it all.

I have a device with sinking NPN inputs and all my PLC outputs are set up to source current (PNP) with 24VDC on the common. :(

I have a device from OMRON to convert NPN to PNP (which i need for the other part of the interface) but it doesn't seem to work the other way around (OMRON PN EE-2002).

I can probably put a relay in to tie the device input to ground when the PLC output comes on but wondering about other methods?....

Help appreciated.
 
I recently posted a couple of bitmaps that should show you how to do it with a resistor for each connection. Remember that when you wire them this way, its like replacing a NO contact with a NC.

http://www.plctalk.net/qanda/showthread.php?s=&threadid=1615

The technique is fine for for one or two isolated connections, but it can be rather labor-intensive. If you have quite a few cross connections, it would be a lot easier to buy the correct flavor input module.
 
Thanks,

Yes, this is just one input and one output. The device I have handles the PLC Input side but not the output.

However, the whole issue is moot now as after I came back from lunck, the PNP flavor of the field device was sitting there on our receiving table. The rep originally said it would take 2 weeks to get (after our ship date) but he'd try to expedite it. I guess it worked 'cuz it's here now.

I'll keep your bitmaps handy for reference though... great info

Thanks again!
 
However, the whole issue is moot now as after I came back from lunck, the PNP flavor of the field device was sitting there on our receiving table.

NOT banghead

They sent another NPN device!!!! ARGH!

But.... the resistor worked great .... once I figured out the function of my PLC output is now inverted.

Thanks ALL
 

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