Centroid Community CNC Support Forum

Double checked how I had things grounded and there were some issues. Thought I had them straightened out but still getting errors.

"412 X (and Y and Z) axis encoder differential error"

I put the black with blue wire on the "G" by itself and the shield ground to the "GC" lug along with a black wire leading directly to machine ground.

From the alarm list:
An error condition was detected in the differential signal levels for this axis encoder. May indicate a loose or severed encoder cable or a bad encoder. This will stop all motion and cancel the job.

I can't imagine all three encoders and cables being bad. I have checked the cables a half dozen times each now and the encoders don't appear to be in bad shape (from appearance).

Is it worth it to send them to someone to get checked out? If so, do you have a recommendation? I'm eyeballing Centroid's 2000 line encoders; not cheap.

Mark

It looks like from the encoder photos on page 1 of this thread that all of the ABZ channel negative wires are black while the positive sides are colored.

My guess is you have the black wires mixed up so they are not paired with the appropiate positive wire.

I appreciate your stab at it Tom. That's an old picture of the original set up. The new set up mirrors the schematic to the "T".

Post a picture of the wires at the encoder and one at the connector.

I hope you can see the detail that you need to. They are for the Z axis. I have the other two torn apart as I was checking them earlier.

That wiring does look right so unless the encoders are all actually bad, my only other guess is the differential signal levels are not going high and low enough. The high signal levels need to be above +-3V and the lows need to be below +-0.5V.

You will need an oscilloscope to check those levels.

Thank you Tom. I appreciate your input.

I checked all my wires one more time and everything was fine.

I work for a contractor that repairs and maintains military helicopters. I am hoping that a coworker who specializes in electronics and avionics can check my encoders. I guess if all else fails I can just upgrade to higher count new ones from Centroid. Just makes me wonder what other surprises await.

Mark

We don't know anything about those encoders. I don't recall seeing a make and model posted. They might not even be TTL output. I would find someone who could bench test them for you.

I guess that I never mentioned make and model in here as I had sent that info to sales back when I was considering the upgrade.

They are BEI Motion Systems Company encoders.

Model: L25J-F2-SB-1000-ABZ-7404-LED-TB-S
Part: 924-010008-1438
S/N: P0033284
Date: 07/25/91

Hoping to have someone at my work take a look at them. I had asked earlier if anyone had recommendation for anyone that I could ship them to, with no response yet. Haven't heard back from my email to BEI yet, either.

Mark

I doubt they all are bad. Something else is probably wrong.

Attached is the datasheet for them. The outputs are driven by 7404 inverters, so you are good there.

You should be able to find someone in your area to test them. I could do it if you absolutely hit a wall.