question about logix 500 ONS instruction.

Hey all,
Im looking for a little clarity on the ONS instruction

When taking a pump from auto to manual, I would like a bumpless transition. So I am moving an automatic pid cv in to the pumps power output, when manual control has been selected.

Im doing this with a ONS instruction, and from there the manual sp can be played with.

If I put the pump back into auto, and then again back into manual that ONS instruction will not move the CV into the manual sp again.

I was under the assumption that if the rung the ons instruction is on becomes false and then true again it should function on the next scan?

Can anyone help me with a way to assure that this will function as intended in the event of toggling like as mentioned above?

Thanks so much for your help.

I suspect you are referencing the ONS storage bit in multiple locations. The storage bit may be used only once.

Are you using the PID A/M bit? For bumpless transfer set the PID A/M bit and then write directly to the CV.

It would help if you told us what processor you are using and post your code ( .RSS file) zip it first if you can.



The PID instruction is also different depending on the processor you have.

I'm assuming a ML1100, 1200, or 1400 since he's using ONS instead of OSR.

Thanks for your help guys,
I did find I was referencing the ons in multiple spots, appears to have solved the problem.

Many Thanks