1746-OB 16 Question about usable outputs

Hi all,

I have a SLC 5/04 that we recently needed 24vdc outputs to control a heating application. I used 4 of the 16 outputs and it works great with PID control and the outputs are connected to SSRs. I also use 4 other of the outputs to send control signals to a remote variable speed fan. Through a series of on and off signals I can remotely set the fan speed without using an analog signal.

Both applications work great. The problem is I can only get usable voltage from 8 of the 16 outputs. All the outputs with the CR designation in the AB wiring diagrams don't give me 24vdc when toggled on. I need to get these 8 other outputs working because we would like to add some additional dc wiring to the PLC.

This is the first time I have worked with this card and any help would be appreciated.

Thanks,

Jamie

Aren't there a jumper involved.

All 16 outputs use the same voltage source on the OB16.

There really isn't anything special about those outputs. the diagram uses the CR designation just to show a general mix of outputs. How are you trying to turn them on? Are you forcing or did you write logic to turn them on? Are you just writing zeros into the output image table?

Keith

My guess is that for some reason your program is not activating the outputs. Do the amber lights illuminate on the output module? If so then you should be able to measure a voltage. You shouldn't need any jumpers on this particular module.

Yup that is the same diagram I was looking at. I will try again and see if I get the lights to illuminate and measure a voltage. Maybe it was just a strange coincidence on how I was toggling the outputs.

I wll try them again.

Thanks

If you can post the program we can take a look at it and see if there is something you are missing.

Also, you might want to take a look at the following discussion from our distinguished collegue Ron Beaufort's web site about the difference between toggling a bit and forcing a bit. Scroll down to the links on "Toggling and Forcing"

http://www.ronbeaufort.com/sample_lessons.htm