[gcamlibel]

I built a cnc controller for steppers and I converted an Optimum BF-20 mill to CNC with this stepper controller and Art’s Mach2. Some picture can be seen at http://gunol.otocamlibel.com/cnc

Nowadays I am interested on closed loop servo control. In fact I have no idea about this however 4 months ago I was at same condition about steppers

Today I bought a DC servo motor with encoder from a local scrap seller. It has only one label written DIGITAL B54715 however google search doesn’t give any result about this motor.

It has two cables at motor side (one white one red) and four cables at encoder side (white, red, black, blue)

I uncovered encoder side of motor; it is not en optic encoder.

I posted detailed pictures of this motor and encoder at http://gunol.otocamlibel.com/cnc/servo you can enlarge each picture by clicking.

If any of you have any idea about this motor, please share with us.

[Greg Fill]

It looks like a magnetic encoder. Check the black ring to see if it is truly a magnet. The ring is magnetized so that it has many North and South poles side by side. The magnet triggers the hall effect sensor as it rotates. I am not sure what the resolution would be for yours. On the 4 wire side I would hazard to guess that the Red would be +5 volts, the black is ground. The quadrature output would be the white and blue. The motor connections of course would be the other two wires.

[Al_The_Man]

I would guess that it is a simple quadrature encoder, two of the leads could be 5v (red) & com (either the Black or blue, you may have to trace them to a ground trace to confirm) the other two the outputs, they may require pull up resitors to the +5 if they are open collector. But the type of medium is not obvious, as you say it does not look like optical, it is hard to see what the composition of the outer of the wheel is, it looks like a magnetic material? Probabally very low resolution 100 p/turn max. maybe.
Al
Greg, we must have been typeing in at the same time.

[gcamlibel]

thanks for quick replies.

For Al_The_Man: you can see detailed pictures of encoder side at http://gunol.otocamlibel.com/cnc/servo it looks like something magnetic.

I will check this encoder with my friends osciloscope tomorrow. I will post the results.

do you know any opensource servo controller?

[Al_The_Man]

Originally posted by gcamlibel
thanks for quick replies.

For Al_The_Man:
do you know any opensource servo controller?

By open source controller , I gather you mean a cnc control? there are some Linux based systems out there but I have not explored that in any depth.
BTW I would guess that motor is rated at 24vdc at around 1500 rpm. If you can spin the armature up to around that rpm and measure the DC output on the armature leads this will give you an idea.
Al

[jimbo]

I believe I have one of those motors laying around. It came out of a DEC printer terminal. It is a Hitachi Permanent Magnet motor. Dont know anything about the encoder though.

Label says:
Torque 30 oz-in
Volts 24vdc
Amps 2.2
RPM 1580
Output 33W
Type TO-M-E
Rating Cont.