Custom machine power ON

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05 May 2017 12:29 - 05 May 2017 15:15 #92700 by my.cnc.brother
Retrofitted by myself Brother CNC TC225 milling machine has more advanced power distribution than usual. There is a distribution plate with contactors supplying main power to XYZ servo drives and spindle drive.
In original setup those contactors were controlled by mainboard through relay and after energisation state of contactors were monitored continuously by mainboard through auxiliary contact mounted on each contactors. I would like to keep such agile solution functional.

What I would like to have is following custom power ON sequence in LinuxCNC:
- after Power On button (power toggle button in Axis UI) press close drive power contactors, but do not enable drives yet
- wait for feedback signal from aux contact
- after receiving feedback signal enable drives
- continuously monitor feedback signal from contactors, if not present -> e-stop?

Could you advice something, please? How to prevent instantaneous servo drive enable after Power ON button switch? How to include additional condition before enabling drives?
Last edit: 05 May 2017 15:15 by my.cnc.brother.

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05 May 2017 14:20 #92704 by Todd Zuercher
Most of the normal servo interface hardware available for Linuxcnc have provisions for servo enable out signals, and there are hal pins dedicated for controlling them in Linuxcnc. What hardware were you planning to use to interface with your servo drives?

Monitoring feed back from something such as a contactor's overload relay, would be easy. But if you just want the machine to enter e-stop, simply wire them into your e-stop loop (which Linuxcnc can both monitor and/or be a part of.)
The following user(s) said Thank You: my.cnc.brother

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05 May 2017 15:02 - 05 May 2017 15:04 #92707 by my.cnc.brother
Yeah, I know how to use classic drive enable output. Actually this works like a charm in my test setup :-).

BTW my setup is: mesa 5i25 + meas 7i77 + original sanyo +/-10V servo drive.

What I want to achieve is to close contactors before enabling servodrives. If I enable servos and close contactors at the same time, there is "unstability" period, resulting in vibrations and shake.

Ps.
Idea with continous contactors monitoring via e-stop is clever and I can easly do this in my hal :-).
Last edit: 05 May 2017 15:04 by my.cnc.brother.

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05 May 2017 15:30 #92709 by Todd Zuercher
Can you have your servo contactors close when you take the machine out of e-stop (F1) , then only enable them when you press F2. (This is how I have mine set up.)

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05 May 2017 18:42 #92717 by andypugh
Replied by andypugh on topic Custom machine power ON
This might be a good use for a simple Classic Ladder system.

I don't understand that, though :-)

What the system on my lathe does is monitor the bus voltage at the drives, and only enables the drives when that is over a threshold (monitored by a wcomp HAL module, I think)

It helps that in my case the drives report back bus voltage to HAL.

I also have a GPIO pin monitoring the voltage at the main contactor coil. (with a protection diode so that my GPIO does not see the breaking pulse). This means that if the E-stop loop breaks then LinuxCNC knows about it.

If your contactor coils are 12V or 24V then the 7i77 GPIO can safely monitor it. (but add the diode, as I did, if the coil does not already have one (some do))

Maybe add a timedelay HAL component or a (long) debounce.

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