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Finally added a safety feature that I wanted

My mill was lacking something very important: the drives would remain powered, and drifting due to test/offset, when EMC2 was not commanding any motion.

Just to clarify: if EMC is holding position, then the drives are held in position by EMC. But if EMC is not holding position, for example because it stopped due to following error, then the drives would start drifting.

It happened a couple of times already that I would forget about EMC left without controlling position, and the mill would drift next day to some unacceptable position and trip the limit.

I finally added an extra instruction to "inhibit" the drives when the axes were not position controlled. Now, if EMC is stopped due to following error, or I turned the motion off, the drives are inhibited and would not do anything.

i
Reply to
Ignoramus12820
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Do you have them inhibited if the watchdog timer expires due to a software crash / hang?

Reply to
Pete C.

If watchdog timer expires, the all output of Jon's PPMC shuts down, and that turns off the main motive power contactor. There is no problem with that.

I really should try to simulate a system crash while moving, for example by pulling a power cord.

i
Reply to
Ignoramus12820

I would STRONGLY recommend putting in a couple relays on the power lines going to the servos. When machine power goes out..it instantly opens the relays and prevents the servos from running away for a second or two as the power supply caps discharge.

My customers busted a bunch of tooling because of that not being implimented in OmniTurns the first couple years.

Gunner

Reply to
Gunner Asch

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