Profile management for rotary

RUIDA RDC6445S Firmware V26.01.16
Chuck style rotary run by swapping Y axis connection to rotary device.

When swapping to rotary setup, my present method is to “load from file” the set of parameters that suit my rotary.
Power down machine.
Swap in the rotary by plugging the Y axis connection to rotary and power up again.
The process in reverse when swapping back to standard X/Y.

There is probably a smarter method of doing this. Any one have some advise?

Don’t cringe but, I hot swap the Y cable … always have…

You can connect the rotary, turn the machine on and press ‘esc’ to quit the homing sequence. You can then load the rotary configuration…


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Do you mean that you swap the stepper driver without powering down?

From everything I have read that is very bad for the health of the driver.
Un plugging is fine, it is reconnecting while powered that is bad.

As far as aborting homing then loading new parameters. That is pretty much the same as my process.

I was hoping someone would have some smart idea for managing profiles.

Maybe… it’s pretty tough hardware and I’ve been doing it over a couple of years at least weekly if not more often.

Inserting or removing connectors causes issues in the interface, usually because all connections don’t ‘make’ or ‘break’ at the same time…

I leave my machine on for the day. My experience with electronics is they fail when you power them up… so I limit how often I power them up…

A motor driver is about $15…


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That’s harmless almost all the time. When it isn’t, the motor driver dies.

Each phase of the usual H-bridge bipolar driver has current flowing through the motor winding and two MOSFETs. When you unplug the stepper motor with the winding energized, the energy stored in the winding inductance produces a (sometimes small, sometimes large) arc between the connector pins. The arc voltage appears across the two MOSFETs conducting the current, raising the high side MOSFET hundreds-to-thousands of volts above the low side MOSFET.

Air has a breakdown voltage around 1 kV/mm. The voltage across the arc drops when it gets up and running, but the damage happens at breakdown. This is all fast enough that the usual assumptions about power supply capacitors, decoupling, and suchlike don’t apply.

The arc voltage pushes the high side MOSFET far above the motor supply voltage, with the current continuing to flow toward the low-side driver, so its body diode does not turn on. The upper MOSFET shuts down as its source voltage rises above its gate, the winding current pushes its body diode into breakdown, and the supply voltage steps upward by another hundred volts or so.

What happens next depends on a bunch of imponderables (usually the phase of the moon and definitely recent karma), but AFAICT the upper MOSFET and its gate drive circuitry generally takes a hit as the semiconductor insulation layers break down.

Again, mostly this doesn’t happen. When it does, the driver is trash and, if it’s one of those fancy all-in-one controller boards with SMD MOSFETs, the whole board is trash unless you’re a dab hand at PCB rework.

The risk-to-reward ratio is much like eye protection in the shop: sometimes you’re really really glad that sliver stabbed your goggles.

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Sorry, I cringed, just a little.

Don’t let it bother you. I understand what I’m doing and the risk that I’m taking, so in the end it’s my choice…

All my solenoids are missing diodes … I don’t let it keep me up at night…

I run air assist and swap out the Y axes motor leads with it hot… if it fails I’ll fix it. The whole machine is really a consumable… considering where it was manufactured…

I wouldn’t recommend it to anyone, and I made a point of that fact that I do and many wouldn’t like it…

Many people that work to keep things straight and proper are usually the ones that turn it on and it no longer works, so who’s the winner…?


Cool, cool…no judgement here, it was just a lame attempt at being funny. :grin:

That’s ok, I get hammered every time I mention that I do that, but it’s still up and running… knock on wood…

I’m also sitting on a hardware replacement for the driver… :face_with_spiral_eyes:

Don’t really trust the Chinese manual on the output of the Ruida… they show it going through an optical isolator driving a solenoid. I know of no optical isolator that will allow 500mA… we know they drive some kind of N channel open collector type output. Many have replaced them…


I know what you mean about the diodes, I bought a package of 100 just to get 2, and they’re still sitting on the bench next to my laser. One of these days. You provide good counsel to those of us seeking it, and we appreciate it. Thank you.

You realize that you know only the tip of the iceberg as you grow older… :face_with_spiral_eyes:


Yah, I know, I watched one roll over once, off the coast of Newfoundland. Iceberg that is. :laughing:

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