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Author Topic: Encoder wiring on OLD machine.  (Read 3209 times)

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Encoder wiring on OLD machine.
« on: January 05, 2011, 02:49:26 PM »
I'm currently replacing a old Allen Bradley Bandit 3 setup with MACH3 software on a early 80's vertical mill.  I realize a lot of hardware will need to be replaced, but I'm taking it step by step.
This is for a mill for personal use, so budget is limited and time isn't very important.

Step one is to get the encoders to read on on Mach 3 software.

There are rotary encoders on the ends of the motors. They have 6 wires coming out of them.  Twisted pairs red-white, black-white, brown-white.  How can I meter these or make a setup to figure out which ones are which?  Or do I need to take them apart to see where the wires end up going. These were going to the computer board on the control unit.  There is a seperate tach signal that goes to the servos.

I build electronics for a living so I have access to any testing stuff I need. 
Thanks

Re: Encoder wiring on OLD machine.
« Reply #1 on: January 05, 2011, 04:57:39 PM »
I think you will find these are resolvers, if so, not compatible with encoder input.
Measure the resistance of each pair, if very low ohms, they are resolvers.
Nosmo

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Re: Encoder wiring on OLD machine.
« Reply #2 on: January 05, 2011, 05:35:09 PM »
if the wire was twisted in delta, it was not an encoder

for mach 3, you need ttl 5volt encoder, ttl encoder had 5 or 8 wires (8 wire if differentiel)
Re: Encoder wiring on OLD machine.
« Reply #3 on: January 05, 2011, 06:39:54 PM »
They have 'encoder' printed on the label.  Not all white wires were hooked up to the CNC motherboard.
Re: Encoder wiring on OLD machine.
« Reply #4 on: January 05, 2011, 06:59:46 PM »
Check for continuity in pairs, if they test for around 28ohms in pairs and no continuity between each pair, then it is a resolver.
Nosmo.
Re: Encoder wiring on OLD machine.
« Reply #5 on: January 06, 2011, 07:40:26 AM »
It was a few weeks ago that I was poking around, but if I remember correct there was a similar resistance across all wires, not just in pairs.
From what I see an encoder wound have 6 wires, A+, A-, B+, B-, +5V and 0V.
Re: Encoder wiring on OLD machine.
« Reply #6 on: January 06, 2011, 10:34:55 AM »
Differential but no marker then.
With no other data you may have to reverse engineer the connections, one you trace the + & - the others can be detected with a D.B. 'scope, or with a meter if turned as slow as you possibly can.
Re: Encoder wiring on OLD machine.
« Reply #7 on: March 29, 2011, 12:30:22 PM »
Been a while, but I took the cover off the motor, and it is clearly labeled. V +/- A +/-, B +/-, and M +/-.  So I'm all set. 
Thanks!