Messages

1

General Mach Discussion / Re: Retrieving position after an e-stop or other position loss

« on: December 07, 2018, 12:59:13 PM »

I don't care about between sessions, though that might be nice, and I guess there's no reason not to do that if the drive were backed (it is not).

I want to preserve position when the machine is moved not under mach control, such as during an e-stop event or position loss event due to over-torque and drive disabling.

What methods does mach software have for updating position based on an external reference?

2

General Mach Discussion / Re: Retrieving position after an e-stop or other position loss

« on: December 07, 2018, 12:50:12 PM »

Yes, it does. It provides the number of accumulated pulses since startup. Same as any other digital encoded servo amplifier.

3

General Mach Discussion / Re: Retrieving position after an e-stop or other position loss

« on: December 07, 2018, 12:13:45 PM »

Since the drive is tracking the encoder starting at powerup, why would it matter?

What I imagine is that on startup, after enabling, the mach software would query the drive to determine position and store that as an offset. Ideally it's all zeroes, but just in case it isn't.

Then, upon subsequent enables (after loss of enable due to estop/etc), the system would re-query and shift mach's internal known position by the amount the drives differ from mach's expectations.

4

General Mach Discussion / Re: Retrieving position after an e-stop or other position loss

« on: December 07, 2018, 12:03:26 PM »

The encoders on the motors are incremental 2500ppr encoders. Standard stuff.
The drive can output the value of current position from powerup. Not at all absolute, but that's not a problem.

I just want to update mach software with the actual position the system wound up in after a position loss event. probably only a few hundred pulses off maximum.

5

General Mach Discussion / Retrieving position after an e-stop or other position loss

« on: December 07, 2018, 10:57:34 AM »

Hello,

I'm building my first system using Mach software. It's a custom unit designed and built in house.
I'm using the warp9 ess board and MACH3 now, tho I'm open to mach4 if it makes more sense.
I've got it built and wired up, it's running well.

The drives are Automation direct sureservo units, the 2kw units. They're actually rebranded delta drives, from what I can tell. Fairly basic, but they do have modbus multi-drop communication and can spit out the motor's actual current position, which leads me to my query...

My question is: Can I have mach3/4 read the actual position of the drives after an e-stop or other position error event where mach would otherwise have lost position certainty due to coasting? I'd like to recover from an e-stop/etc without needing to re-home.
Is this a feature that's already written, and/or would it be reasonable for me to add if it isn't?

Thank you