Open loop ok, no operation in Axis

Guys not sure if this belongs here or in the Axis section.

I got both X and Z axes moving in open loop and reading position feedback but when I open in Axis the axes just drift.

I see the feedback position moving with the drift ... like the control is not closing the position loop so it is not holding position.

I have a feeling it's just some fundamental error preventing enable ... like an estop input or something that got added in there while I was pasting things together.

Have a look at my files and see if anything jumps out.

cheers










The drives have no separate enable pins.

Thank you

This is expected since the P terms are 0

HOWEVER be aware that you may get a runaway as soon as you set a non-0 P term

So its crucial that your drive enables be under LinuxCNC control so LinuxCNC can disable the drives if a following error is sensed

PCW wrote:

This is expected since the P terms are 0

HOWEVER be aware that you may get a runaway as soon as you set a non-0 P term

So its crucial that your drive enables be under LinuxCNC control so LinuxCNC can disable the drives if a following error is sensed

Thank you for the response. I tried P values of 50.0 on both axes and still they are creeping.

The strange thing to me is the commanded position is moving with the creeping. Shouldn't the controller be sending a position of zero as command? Instead it is following the axis. It makes sense how an axis creeps especially in velocity mode when sitting idle in open loop because any voltage is a velocity ... but if it is closing position loop which should be zero, why is the commanded position moving? Following error staying at zero also..

What else could I look at?

Thank you for any thoughts.

cheers

edit: motors are unhooked from machine so no damage will occur if they run away

Are you sure the commanded position is creeping?
( Axis's DRO shows the feedback position, not the commanded position )

PCW wrote:

Are you sure the commanded position is creeping?
( Axis's DRO shows the feedback position, not the commanded position )

I'll double check it is command.

The function boxes in the axis gui are grayed out/not clickable if that means anything.

If following error was staying zero wouldn't that mean the command is equal to feedvack? I will double check.

Analog out is zero.

It is like it is just minimal voltage on the analog output.

The e stop doesn't seem to do anything. Just throwing out observations.

I will double check there are not enables on the drives I have brain faded.

Cmd-pos is following feedback in lock step.

There are no enable inputs on the drives. They are wired into limit switches which shut the drives down when triggered. And there are override buttons on the original operator panel that orverride the switches to jog off.

I'm mentioning this because I do no "enabling" of any outputs or halpins (that I'm aware of) related to drives. I guess this is all just happening in the background when I launch axis? edit: My thought process here being when does the control actually look at the current position and close the position loop to it? Do I have an error preventing this from happening?

I included some e-stop ladder when I was first putting things together and deleted those ladders. Did a variable get introduced somewhere that is related to e-stop or something? Sorry for the rambling post. Just trying to shed light on the problem.

Are my pyvcp's with my classicladder tool changer holding things up?

My ladder is running looking at a pyvcp for a tool changer value for now. I will be calling that with an M6 command ultimately.

Not having linuxcnc enable the drives is a safety issue
(a bad encoder connection/ drive /controller fault could lead to a undetected runaway)
I would get this fixed first

(this will also fix the drift since the drives will not be enabled until linuxcnc is in control)