Clear DROs and force operator to re-home after EStop

[Jimbo]

Is there any way to request the CNC software to clear the DRO's (display dashes) and force the user to re-home the machine when an EStop condition has occurred. Like return to a state similar to the state the control is in on initial power up of the PC.
Since its open loop, if there is ever any reason for a drive hiccup, I think it would be nice to have the operator be required to re-home. My M15's retain the encoders with servos free, but with the Acorn, I'm concerned about drive faults, miscommunications or other drive issues that would cause the machine to be not in sync with the control.
I read a lot of posts, watched several videos, and poked around in the PLC but want able to discover a clear path, or if it was even possible without power cycling the PC which just seemed like a brute force solution to a simple idea.
Am I missing the obvious? Any thoughts, pointers, or constructive criticism would be appreciated.
Thank you
Jim

[cnckeith]

hello.
some easy options for you.

- Use the Reset Home button on the VCP to re run the home program therefore resetting the machine home position.

- or load the cncm.home program using F2 Load and run the program with cycle start.

- power cycle method... you don't have to power cycle the PC, just close CNC12, and power cycle Acorn then restart CNC12..CNC12 then asks for user to home the machine on startup of cnc12

[Jimbo]

Great, Thank you for the response.
So no way to get it to clear the DRO's and return to the CNC app entry point (or at least simulate that) programmatically with out power cycling something? Id like to create a fail-safe condition. You have some great recommendations. I believe all of them require the operator being responsible enough to know that if an EStop happened, they have to go thru the re-home procedure. I was hoping to force them/me to do it somehow.
Drivefault seems to force an EStop toggle but no mention of homing. I would like to squeeze in a home required step after clearing the EStop. Otherwise how do I know the drives didn't move on their own without some sort of feedback if resetting EStop just picks up where it left off?
--If drivefault then must rehome.
On a closed loop not rehoming seems ok after a drive fault cleared but on an open loop to me it seems like it should be a requirement...
Is my thinking wrong?

[cnckeith]

with open loop system it is common to rehome much more often than a closed loop system, that is why the button "Reset Home" is on the VCP for open loop systems and not for closed loop systems.
running Acorn in a hybrid closed loop configuration drastically reduces the amount that a user has to re home the machine and goes a long way in eliminating lost steps so that is the number one recommended method of using an Acorn CNC controller. (with AC brushless motors and drives or will closed loop stepper motors and drives)

[Jimbo]

I agree, and my goal is not to eliminate lost steps in the typical sense of the words. I am using a hybrid closed loop system and its highly effective. But when the drive faults or EStop is pressed the motors can free wheel so home is essentially lost. I was simply looking for a way to prevent running a program or setting a zero until it had been re-homed. Just seems like if the software knows a drive has faulted and knowing its running is an open loop system, that it should call for a re-home at that point and I was trying to emulate that (create a comfort zone). But I understand that's just my thinking. Not trying to be critical or confrontational, just curious if there was some way I could do it.
Thanks for your feedback!

[cnckeith]

alot of AC drives can continue to read the axis motor encoder position in an Estop condition then when drive power is returned and drive fault cleared the drive will correct the motor position if needed. it all depends on the make/model and how you have the axis drive wired and configured.

[martyscncgarage]

I agree, and my goal is not to eliminate lost steps in the typical sense of the words. I am using a hybrid closed loop system and its highly effective. But when the drive faults or EStop is pressed the motors can free wheel so home is essentially lost. I was simply looking for a way to prevent running a program or setting a zero until it had been re-homed. Just seems like if the software knows a drive has faulted and knowing its running is an open loop system, that it should call for a re-home at that point and I was trying to emulate that (create a comfort zone). But I understand that's just my thinking. Not trying to be critical or confrontational, just curious if there was some way I could do it.
Thanks for your feedback!

Describe the make and model of your drives please....
Marty

[Jimbo]

That's good to know moving forward. Right now I am using Gecko 320 drives. (DC servo) They work good, but on error they just kill power to the drives and have no retention of the encoders.
Ive been thinking if its not possible to return to the startup screen then maybe just setting a flag and doing something like message the operator and disabling DoCycleStart or whichever until the flag is cleared by a homing. But I think I'll have to get my head a little bit farther around the PLC code before I can see if something like that is feasible. Everything works great, I just thought I could create a simple safeguard and was soliciting for clues.

[martyscncgarage]

Yeah, you just have to train the operators...

[tblough]

Well, you could always put a NC relay on the power line leading to the PC and have the drive fault output trigger it.