Hi everyone, be good to hear suggestions, I will try to explain as best I can.

Scenario

I get a fault and trace it to a missing output on a 24V output card. I assume the output has failed and swap the output for a spare output and change the program to suit, still no output present. So I try another, same problem.

It turns out that no other 24V output will work, only the ones being used originally, no matter how many I try I cannot get another to work.

There is a 110V card, I have changed / added outputs on this card with no issues, all works fine.

I have checked that none of the outputs are duplicated within the program and I have checked all of the cards for supply voltage.

Any ideas?

Thanks

Hello Rob;

Our help could be more precise if we knew what model of 24V Output card you are working with, and the CPU you are using.

My first thought., if all these missing outputs are from the same (or similar) modules, is a wiring problem  a missing power connection required to drive the ouputs. Very often these connectorsis marked L+ and  M.

As an example (for a S7-300 DO module):

https://support.industry.siemens.com/cs/ww/en/view/8859629/97352616203

Check out the wiring diagram fo your own module and verify if you have all the required connections, as a first step.

Hope this helps,

Daniel Chartier

Thank you for your reply.

The outputs are all on the same card, the other (already used) outputs on the card are working ok,  when I try to add/use a spare output, I get no output. I will find out model names etc and post.

Hello,

These spare outputs are on the same group as the working outputs?

Are the leds on?

Take a clear picture of your wiring on the card.

Regards,

Marcjan

Yes these spares are on the same group as the working outputs, no LEDs come on. I also have the same problem with other output cards on different ET200 racks (on the same PLC), it seems that I cannot re address any spare 24V output, the only ones that will work are the ones currently used, its like there is something stopping any changes. 

I'm unable to send a photo of the wiring as I need to email the photo from my phone but the signal here is really poor. 

The wiring has been checked and supply to the cards is correct.

Thanks

Rob

Robotic Rob

Yes these spares are on the same group as the working outputs, no LEDs come on. I also have the same problem with other output cards on different ET200 racks (on the same PLC), it seems that I cannot re address any spare 24V output, the only ones that will work are the ones currently used, its like there is something stopping any changes. 

I'm unable to send a photo of the wiring as I need to email the photo from my phone but the signal here is really poor. 

The wiring has been checked and supply to the cards is correct.

 In the picture, first postet, has Digital outputs on QB4, QB5 and QB108, QB109, QB110, QB111. In the second picture you posted, you are trying to use digital outputs from QB6 and QB112, and they don't exsist in your ET200M station...

I have resolved the issue.

The hardware configuration was incorrect, I compiled and then downloaded system data and the outputs now work.

I'm not sure how this has happened, I assume someone has made an alteration to the hardware and made a mistake.

All the best

Rob