AMC servo drives pictures

I am trying to convert my 1987 cnc mill with the anilam crusader m control to Linuxcnc. I bought 3 advanced Motion Controls be25a20h drivers but I have no idea how to wire them, mostly because I don't understand the terms. Does anyone have a picture with the wires labeled by chance. My mill has the SEM brushed servo motors with the linear scales and the tachos,there are no encoders but I do have some, just not sure if it is worth installing them or not. Any help would be greatly appreciated.
Thanks Mike

I cannot give an exact connection diagram because I don't know all of your hardware
but there are three basic analog servo interface "sections": ANALOG, ENABLE, ENCODER

ANALOG:

ENABLE:

Enable is a bit awkward since the BE25A20H has a disable (inhibit) line that must be grounded before LinuxCNC starts, the easiest way to do this is with a relay (this relay may in fact already exist in the old control) Another option instead of the relay is a strong pulldown resistor from the /inhibit pin to ground and then driving the pin hive via the 7I77s ENAble outputs. This requires tapping onto the drives +5V encode outpu to supply the pullup power.

Some drives can be modified to change the default inhibit polarity so it would be wise to determine this before starting in case the relay/pulldown resistor parts can be avoided

assuming inhibit must be grounded to disable the drive:

ENCODER

Depending on whether you have a TTL of differential interface scale you will connect
(for TTL encoders, the 7I77s /QA0,/QB0,/IDX0 are left unconnected)

Thank you very much PCW for taking the time to help me out, I will see if I can get things wired up and working.
Thanks Mike

BE drives are for brushless motors You would be better off with standard 25a20 brush drives. They have input for the tach. You can use the brushless drives with brush motors. All of the manuals are available from Amc website. You can also set a jumper in the drive to set the enable to on, I set them up this way and use a contractor to power my dc supply. Hitting estop cuts power to the machine. You might wanna look at the brushed drives.

Any reason to not use the drives that came with the machine?

My mill has the SEM brushed servo motors with the linear scales and the tachos,there are no encoders but I do have some, just not sure if it is worth installing them or not. Any help would be greatly appreciated.

Just read in the linear encoders to linuxcnc. You'll get some dithering which can be annoying if you have excessive backlash but on my BP it's not an issue.

I already have the brushless drives.

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The motors are brushed. Are you switching out the motors to BL type?

BE drives are for brushless motors You would be better off with standard 25a20 brush drives. They have input for the tach. You can use the brushless drives with brush motors.

JR1050, was that a typo or are these drives compatible with brushed motors?? I didn't review the docs...


If the drives are still in the control box with the power supply etc working I would just connect the 7i77 to them. The stock drives will already be tuned and relatively quick to get going.

In the manual, there is a section on driving a brushed motor with a brushless drive. I have done it with amc drives , I have a huge dc motor on the z axis of my mill and it can easily pull 35 amps. Amc only make a brushless drive that handled that much current. It was a B something not a BE, it had the input for the tach.
All this being said, trying to run a motor in current mode with glass scales could be tricky, if you can use the tachs, at least you can close the velocity loop in the drive. If you have a rotary encoder, the drive will convert the signals into velocity feedback, I think ..... The 25a20 brushed drives are cheap on eBay and you will quickly recoup your costs by selling the BE drives. Curious, are the original drives functional?

The brushless drives have a negative tach in, is that not the same thing.