How to determine unknown encoder pinout ?

[Argofanatic]

Hi, I have a Bayside (now Parker) brushless servowheel for which I am unable to find any thorough documentation.

The encoder has 5 wires. Black, Red, Orange, Green, and White.

Can I assume that Black and Red are ground a power ? Is there any way I can determine the pinout with my only a multimeter ? From the single page I was able to find, the encoder voltage is 6.5V. I am also unable to dissasemble the motor to physically look at the encoder.

Any help would be appreciated.
Marc.

[Al_The_Man]

As you say, you can probabally safely assume that the Red & Blk are Power & common. Apply power and apply a voltmeter to common and the O,G & W in turn and as slow as you can, turn the shaft, you should see a transition from common to + on each, the exception will be the marker pulse which will only occur once per rev. so it is hard to catch.
If you do not see any results on any, try a 1k resistor for each to +, if you now see results, it is probabally an open collector output.
If it is a brushless motor however, this may be the hall commutation pulses, and if so you will get large resolution pulses out, all three the same and the amount will depend on the number of poles.
Al.

[Argofanatic]

Al, you ARE The Man !

Red, Black as predicted.
Nice transitions on Orange and Green, leaving White for the index.

Thanks !

[Argofanatic]

Hi, I've finally managed to hook up a power supply to my bayside servo controller and I have life!

The controller is an analog +-10V. I've fed the 6.25V power source for the encoder (I couldn't find a pot) into the input and the motor spins. WHOHOO!

My question is this.
How can I determine that I wired the encoder correctly ???
Does the fact that the motor spins conclude that the wiring is correct ?
What luck would that be to get the one of 6 possible combinations on the first try.

Thanks,
Marc

[Al_The_Man]

It is only two comibinations if you say it is single ended and have identified the marker.
Is it an Intelligent drive, where the encoder goes into the drive?
The if only three wires and no other connections, it sounds like you just have commutation pulses and not encoder output.
You can confirm the nature of the pulses by 'scope, or with a meter turning the shaft very slowly.
Is it a DC Brushless motor/drive or AC sinusoidal?
Al.

[Argofanatic]

Hi Al,

The motor is DC brushless and the encoder is encased within. Three wires for the encoder (plus Vcc and Gnd) and another three wires for power. Although unable to find documentation for the motor or drive, the board uses an MC33035 motor controller. I painstakingly reverse engineered what I could from the various datasheets of the chips used. So far so good.
The encoder inputs to the MC33055 are simply labeled Sa, Sb, and Sc.

Please pardon my ignorance If I'm not providing the correct information for you to help me. I do appreciate the help though.

Marc.

[Al_The_Man]

I think you will find that the Sa~Sc are commutation pulses, not encoder, so it is possible you do not have encoder feedback on the motor.
Al.

[Argofanatic]

Man you are fast !
And correct.

My trusty multimeter has a frequency counter on it, I get 445hz on all three outputs (at 6.25V command voltage). Therefore no index seems to be the conclusion.

Just to confirm then, if they are simply commutation pulses, does the wiring sequence matter ? Since I get rotation is everything OK.

Marc.

[Al_The_Man]

Yes, if the motor turns in both directions without sign of hesitation or judder, then you probabally got it right first time.
Al.