Biesse Rover 346 Retrofit

There should be a way to do this. If there isn't someone aught to make one, because it isn't an uncommon machine configuration.

First lets nail down exactly what your machine behavior is. The limit switches are fed to your servo drives. Are they also connected to Linuxcnc? Do the drives differentiate between pos/neg limit events? Some drives will only inhibit movement in the direction of the detected limit.

It would be nice if there were an override-limits hal output pin that you could use for this, but I don't think there is one. Probably the easiest solution, would be a physical momentary switch/button to use as a limit override. It would physically bypass all of your limit switches. You would press and hold the button while powering up and enabling the machine. You would have to hold the button until you jogged the machine off of the limit.

Todd wrote:

There should be a way to do this. If there isn't someone aught to make one, because it isn't an uncommon machine configuration.

First lets nail down exactly what your machine behavior is. The limit switches are fed to your servo drives. Are they also connected to Linuxcnc? Do the drives differentiate between pos/neg limit events? Some drives will only inhibit movement in the direction of the detected limit.

It would be nice if there were an override-limits hal output pin that you could use for this, but I don't think there is one. Probably the easiest solution, would be a physical momentary switch/button to use as a limit override. It would physically bypass all of your limit switches. You would press and hold the button while powering up and enabling the machine. You would have to hold the button until you jogged the machine off of the limit.

They are not connected to linuxcnc. I intend to do this eventually but they are not connected at the moment. I could tie a solid state relay to the limit going to the drives but I do not know what that would do to the drive if its input could handle it or not. I already passed the wires for adding them to LinuxCNC for the X and Y. So they should be a no brainer.
There are two limits connected in series and one input into the drives, so If I would use your scenario I would remove the ability to jog off the other way so as to to drive it into the hard stops.I could achieve this by disabling the job buttons that would drive it into the stops.I am not worried for the X and Y because I can just push it off the stops, but the Z however is 800lbs so I won't be able to do that. I would implement this on the Z only.

The X and Y should theoretically never get to the limits becasue of the soft limits.

Another option is to place styrofoam on the bottom of the Z so it doesnt hit the limit and then just jog off when I power up the machine. In theory I should leave air on the machine so it doesnt hit its stops. Once I fix the leaks..... Only when compressor malfuctions at night it will drop, so I would need some means of getting it off the stops.

OK I got XYZ working.

The Z is going down while pressing page-up. And that is backwards.

I dont want to mess this up and get a runaway becasue I only have 6" to play with a 800lbs Z. Dont want to break anything.

Do I just swap the output scale on the joint? The min is - and max is +.

Swap them so the OUTPUT_MIN = 10.0 and the OUTPUT_MAX = -10.0

To reverse an axis you need to reverse both the input (encoder) scale and output (analog out) scale

That is, you change the sign of both hm2_5i25.0.encoder.0N.scale and
hm2_5i25.0.7i77.0.1.analogoutX-scalemax

(if you reverse just one of these, you will get a runaway)

You do not change the minlim and maxlim values

The idea with the limit override button, it is just away to fool the drive it is off the limit, so you can enable them and jog off of the limit switch. It should not cause a crash unless you jog the wrong way when using it. I've used lots of machines that have something like this setup and it works perfectly fine.

A possible way to keep your head up. Some of our machines have an air actuated valve on the counterbalance air cylinder. So when the air is shut off or the machine is shut down, the air pressure is trapped in the counterbalance so the head can't fall. (works great so long as the air cylinder doesn't leak.) Most of our other machines have a pin that locks the Z screw when power or air is removed.

PCW wrote:

To reverse an axis you need to reverse both the input (encoder) scale and output (analog out) scale

That is, you change the sign of both hm2_5i25.0.encoder.0N.scale and
hm2_5i25.0.7i77.0.1.analogoutX-scalemax

(if you reverse just one of these, you will get a runaway)

You do not change the minlim and maxlim values

So change the ENCODER_SCALE and OUTPUT_SCALE to negative values?

Those are the variables from what I see to the hm2_5i25.0.encoder.0N.scale and hm2_5i25.0.7i77.0.1.analogoutX-scalemax
from what I see.

I had this conversation with you Peter on my VMC.....lolI guess it didnt sink in.

/EDIT On my VM40 I only change4d the OUTPUT_SCALE to negative, the encoder scale is positive. I just checked......

PCW wrote:

To reverse an axis you need to reverse both the input (encoder) scale and output (analog out) scale

That is, you change the sign of both hm2_5i25.0.encoder.0N.scale and
hm2_5i25.0.7i77.0.1.analogoutX-scalemax

(if you reverse just one of these, you will get a runaway)

You do not change the minlim and maxlim values

Thanks PCW, that worked....

So change the ENCODER_SCALE and OUTPUT_SCALE to negative values?

No, change their signs (change to - if existing is + and + if existing is - )

Todd wrote:

The idea with the limit override button, it is just away to fool the drive it is off the limit, so you can enable them and jog off of the limit switch. It should not cause a crash unless you jog the wrong way when using it. I've used lots of machines that have something like this setup and it works perfectly fine.

A possible way to keep your head up. Some of our machines have an air actuated valve on the counterbalance air cylinder. So when the air is shut off or the machine is shut down, the air pressure is trapped in the counterbalance so the head can't fall. (works great so long as the air cylinder doesn't leak.) Most of our other machines have a pin that locks the Z screw when power or air is removed.

I understand but that override button wont do anything.... The limit switches are going directly to the drives. So unless I can energize an output and physically simulate "limit switch ok", or connect limit switches to Linuxcnc, then that button does nothing for me.

There are valves that are letting air out via exhaust port. The compensation cylinder is not leaking. so I dont know about this issue yet.

bevins wrote:

I understand but that override button wont do anything.... The limit switches are going directly to the drives. So unless I can energize an output and physically simulate "limit switch ok", or connect limit switches to Linuxcnc, then that button does nothing for me...

That is exactly what the override button must do, bypass the signal of the limit switch.

Surely the original system had some similar arrangement for overriding the limits. (On one of our machines the power on/machine enable button is also the limit override, so you have to hold that button in until you jog off the switch.)