jog a velocity stepgen while paused

I have a stepgen running in velocity mode from a hypot component that would be handy to be able to jog it while my machine is paused. The part I need to move is run by a servo through a belt drive and I can disable the drive and reach in the machine to grab the pulley and move it but it is a bit of a chore depending on where the gantry is. One options I can think of are to have a separate stepgen hooked up to the same pins that I could control when paused by a switch or keyboard but I don't think that would work while paused. Another option would be to hook up a cheap signal generator in parallel from the BOB to the servo drive to feed it steps while LinuxCNC is paused but that sounds like a good way to damage the drive. Can LinuxCNC stop in mid-step where the breakout board may, or may not be sending a step signal to the servo drive?

Thanks, Badger

Just add an offset component between the joint command and the stepgen.
linuxcnc.org/docs/2.6/html/man/man9/offset.9.html

Thanks Todd. I was thinking that offsets would return to the previous position like "moveoff" but I will try to figure out how to implement it.

The offset component will hold the value set to offset.N.offset. as long as you can live with the joint moving at the max settings of the stepgen. If you want more controlled motion you will need to add a few more things like a limit3.

If it's a velocity stepgen then you could use a mux-N component.

Connect the existing PID (?) to the in0 input of the mux. setp the other inputs to varius jog speeds. Connnect the .sel bits to the fast/slow jog buttons.

The PID will attempt to return to the original position when re-enabled. You will tend to get following-errors too.
The solution probably involves the offset component and a sample-hold to store the current offset that is latched when the PID is re-enabled.

If there isn't a position loop, then there is no need for the extra stuff.

Nah, why mess about with something that will give you following errors, just use a limit3 to the offset connected to the position input of the PID. You should not get any following errors then. (if it's all connected right) The limit3 should smooth out the step change in position command and the offset will handle the feedback.