New Keling DC servo - won't stop..

[Spinnetti]

First off, I'm a bit of an electrical dunce, so hopefully this is just a dumb miss.

I have a Mach3 controlled 4 axis mill with DC servos, US digital encoders and Gecko drivers. These encoders have 5 wires, (green, white, red, black, brown) of which all are used except the brown. The mill works just fine.

I set up my 12x37 lathe to also be servo controlled, and got big Kelling servo motors. I used the same encoders, and pin assignments, but when I arm the Servo box, the motors just run away. In fact, regardless of what I do with ports, pins, or even plugged in or not, the motors always run away when armed. Even if I disable all outputs in mach or unplug the parallel cable or encoders the result is the same.

What am I missing here? Was hoping to get running tonight....

[Al_The_Man]

Is it motor/encoder phasing maybe? try swapping the two armature leads on the motor.
Al.

[Spinnetti]

Is it motor/encoder phasing maybe? try swapping the two armature leads on the motor.
Al.

You mean the +/- power leads or two of the encoder wires?

thanks...

Well, either way, I changed the power leads, and now it just free runs the other way... something wonky. The controller doesn't see it at all, but on my other servos they still work fine.... (same brand encoders)

[Al_The_Man]

Either would do it but to test it is usually easier to swap the +- motor leads.
Al.

[awerby]

Usually, servo runaway means that the system isn't getting any feedback from the encoders. That's what regulates the servos. Take a close look at the encoders - are they getting power? Are the encoder inputs and outputs hooked up correctly? If, as it sounds like, you swapped these encoders off other motors, make sure they are adjusted and installed correctly, so the read heads can "see" the calibrated discs.

Also, if the servos are a long way off, on more than 5 ft of cable, you might be inducing some RFI that's influencing the system. In that case, a differential system might help - US Digital probably has a kit with sender, receiver, and shielded cable that will work with your encoders. They also offer tech support, so you might try calling them if trying our suggestions doesn't fix your problem.

Andrew Werby
ComputerSculpture.com — Home Page for Discount Hardware & Software

[Spinnetti]

Usually, servo runaway means that the system isn't getting any feedback from the encoders. That's what regulates the servos. Take a close look at the encoders - are they getting power? Are the encoder inputs and outputs hooked up correctly? If, as it sounds like, you swapped these encoders off other motors, make sure they are adjusted and installed correctly, so the read heads can "see" the calibrated discs.

Also, if the servos are a long way off, on more than 5 ft of cable, you might be inducing some RFI that's influencing the system. In that case, a differential system might help - US Digital probably has a kit with sender, receiver, and shielded cable that will work with your encoders. They also offer tech support, so you might try calling them if trying our suggestions doesn't fix your problem.

Andrew Werby
ComputerSculpture.com — Home Page for Discount Hardware & Software

Thanks Andrew...

> Encoders are new, they are just wired just like my other ones which work fine with the same controller.
> Leads are new, shielded and from US digital to match with the encoders.
>The software is not "seeing" the encoders at all, so I assume the wires to my breakout box are wrong.
>The only real difference is that on my other encoders, there's just 4 wires, but on the new ones there are 5 - a "b channel", but I assumed that was not needed.
> Looks like I need to take the control box apart to see what wires are going where. I assumed that the pinouts would be the same, but I guess maybe not.

Do you need both the "A" and the "B" channels wired? I would have thought not.... Thanks for the tips....

Dave.

[Al_The_Man]

Gecko take single ended encoders, Just A & B if you have A&B complements or a marker pulse, these are not connected.
You mention software is not seeing encoders?
Mach does not see them, just the drives.
Al.

[Spinnetti]

Gecko take single ended encoders, Just A & B if you have A&B complements or a marker pulse, these are not connected.
You mention software is not seeing encoders?
Mach does not see them, just the drives.
Al.

Ok, I guess my point was that Mach and the drives work fine with my other motors and those also have US digital encoders, but with these motors they just free run uncontrolled when hooked up - I would think the default mode would be "off" rather than free run. I have the Black, White, Red and Green wires hooked up same as my other motors. Just odd that results aren't the same. Kinda at a loss.

[Al_The_Man]

Did you try swapping the motor leads, this is the same effect of swapping the encoder inputs in order to pin it down?
Al.

[Spinnetti]

Did you try swapping the motor leads, this is the same effect of swapping the encoder inputs in order to pin it down?
Al.

Yep, swapping the motor leads has it free run in the opposite direction..... Since the controller hasn't changed and still works fine (just used it on my mill 15 min ago), its gotta be something different between the encoder pinouts between the old version I have and the new ones. Just not sure what.

[Al_The_Man]

Disconnect motor.
Turn the motor/encoder as slow as possible and see if you see a 0v to 5v transition on the A & B pulses to common on the drive input.
Al.

[Spinnetti]

So I probably just have my wires hooked up wrong, but not sure why. So on my Mill motors, it uses White, Black, Red and Green, but not brown. I was guessing it needed the index and A per this picture, but sounds like I need A&B and not the index one?