Question about proximity switches

[larsclark]

Hello all,

I am not terribly experienced with all this stuff so forgive me if I am asking a silly question. Hopefully there is some simple answer here, but I am stumped.

I am wiring up a control panel with a 1769 L24ER-QB1B with a thermocouple module and integrated 16 ch input, 16 ch output. The PLC, thermocouple module, HMI and another peripherals are all talking to nicely and the programming seems to be working, but I cannot get the proximity switches to reliably work!

We are using CPS9H-AP-F Magnetic positioning switches PNP N.O. 5-28VDC. with a 24 VDC power supply

When I plug one into the input the PLC does not see it. Additionally assuming I put the switch on position 0, then when I take a voltage meter to the other inputs on the integrated card I get a reading of 22 volts on 1 through 7, zero on 8 through 15.

Any thoughts would be great!

 

[James Mcquade]

Welcome to the forum.

I am assuning you have a 16 point dc input card.
from your description, i would say that you have not wired the common terminal for inputs 8-15 to the dc power supply.

regards,
james

 

[larsclark]

James,

Thanks for answering so promptly.

I just checked the machine I am trying to copy and: indeed, yes it has power going to the card which I omitted in the machine I am building!!!

haha victory is mine! or yours rather...

Thanks!