Encoder Differential Error

[jeingham]

CJD,

Thanks for looking at this for me, answers to your questions are below:

1. >> I had that issue that would come and go for several months. Mine was always on the 4th axis encoder. When I watched the step count, the other servos were rock solid, but that one would drift back and forth several steps, even when the servo was stationary. I assumed I had a bad encoder, and was shopping for one under the $500 going rate.

2. >> On a whim, I removed the servo cap and cleaned all the internals in the encoder area with contact cleaner, and I cycled the connectors a couple times each. I have not had the issue since. These are optical encoders, and I think some dust and dirt can cause them to act up.

3. >> Oh...I was wrong. I did have one more instance where I started to get the machine to trip with "encoder error". It turns out I had used a brass mallet to tap the 4th axis trying to tram it in. In tapping I had knocked a connector off inside the encoder cap. Dumb mistake.

4. >> Anyway, the moral of all this, is the easiest thing to check are all your connections and to clean the encoder.

1. >> Oh man, I hope I did not toast my encoders, that would be bad. I've been so careful with them, not cheap. I am prepared for that though, it will not be pleasant but I am determined to get this done one way or the other.

2. >> Will keep that in mind. I've tried to keep everything a sano as possible but you never know.

3. >> No hammers involved in the installation of these encoders. I've tried to be very careful handling them.

4. >> Will keep that in mind as I track this down.

John

[jeingham]

Marty,

Again thanks, read on:

Also, the way you configured your home/limit switches aren't going to work as they are for X/Y. Please tell us where your switches are on your machine and why you configured the software the way you did:
Limits.JPG

>> I have one single NC switch on X and one on Y with triggers at each end of each axis.

>> The Z axis has two NC switches and one trigger.

>> There is a table of settings on the on the schematic but I had trouble understanding which configuration applied to my configuration. My intention was to ask this forum when and if I got to that point.

John

[jeingham]

Marty,

Answers below:

I noticed you PID screen, your index pulses are all showing (asterisk next to each axis letter) that's too coincidental. Are your encoders connected when you took that picture?

So you put the connectors on both ends of the cable. Where did you get the cable?
Show picture of the encoder connector and it's pin assignments and you cable color chart you made and followed along with your DB9 pin connection

>> No, encoders were not plugged in. I showed that just to indicated which screen I was looking at when I did the test (I think). As I recall when I tested, encoders plugged in, I did not see the asterisk.

>> Got the cable from Centroid.

>> Here are pictures of the color chart I made and followed:

All three together

Pigtail to Cable - With Function Only

Pigtail to Cable - With Pin Assignment and Function

Schematic with Pigtail Colors

Frankly I had trouble with the matching of the wires. If I screwed that up after the amount of time I put into trying to get it right I can see why you *HIGHLY RECOMMEND* buying Centroid cables. I will do that in the future for sure if not to bail myself out here.

I'm hoping you can see the error here.

[martyscncgarage]

Please scan the sheet that came with the encoders.

[martyscncgarage]

Marty,

Again thanks, read on:

Also, the way you configured your home/limit switches aren't going to work as they are for X/Y. Please tell us where your switches are on your machine and why you configured the software the way you did:
Limits.JPG

>> I have one single NC switch on X and one on Y with triggers at each end of each axis.

>> The Z axis has two NC switches and one trigger.

>> There is a table of settings on the on the schematic but I had trouble understanding which configuration applied to my configuration. My intention was to ask this forum when and if I got to that point.

John

If you have one switch on X and Y axis then you have to rely on soft limits for the other end.
You can't use one tripper on each end of the axis to trip ONE switch.
WHICH end of X and and WHICH end of Y is your switch on??

Your alternative is to add a physical switch to the other end of each X and Y axis

[jeingham]

All,

If it helps at all, here are two videos:

My wiring color charts...

(I posted images as well in one of my responses to Marty

A general tour of my machine as it sits now...
https://youtu.be/i-wd1M88TKA

Thanks in advance here, very nice to know y'all got my back. This project has been quite the challenge.

John

[jeingham]

If you have one switch on X and Y axis then you have to rely on soft limits for the other end.
You can't use one tripper on each end of the axis to trip ONE switch.
WHICH end of X and and WHICH end of Y is your switch on??

Your alternative is to add a physical switch to the other end of each X and Y axis

Yes, got it, one tripper and software limits, I was sort of aware that would need to be the case.

X switch is in the middle pretty much, Y too. Trips are at either end of the range of travel relative to the single switch.

Will contemplate second switch.

John

[martyscncgarage]

If you have one switch on X and Y axis then you have to rely on soft limits for the other end.
You can't use one tripper on each end of the axis to trip ONE switch.
WHICH end of X and and WHICH end of Y is your switch on??

Your alternative is to add a physical switch to the other end of each X and Y axis

Yes, got it, one tripper and software limits, I was sort of aware that would need to be the case.

X switch is in the middle pretty much, Y too. Trips are at either end of the range of travel relative to the single switch.

Will contemplate second switch.

John

If you have one switch you need to fix it in the CNC12 software configuration. You didn't answer which end of the axis the switch is on so I can't help you there. You will have to either jump the unused limit switch input to COM or use the appropriate limit switch defeat on AIO DC

[martyscncgarage]

All,

If it helps at all, here are two videos:

My wiring color charts...

(I posted images as well in one of my responses to Marty

A general tour of my machine as it sits now...
https://youtu.be/i-wd1M88TKA

Thanks in advance here, very nice to know y'all got my back. This project has been quite the challenge.

John

Great.
But, I will not rely on your hand printed notes to generate the proper way I would make up the cable.
I NEED the sheet that CAME with the encoder please....or I won't take the time to do it.

Marty

[jeingham]

Marty,

Please scan the sheet that came with the encoders.

I dug it up and I think I see my error!

Gotta check tomorrow but it appears that I have the A and /A AND B and /B wire pairs inverted.

I'm guessing that would be enough to screw things up. Let me know if you know.

I'm sure you will see the error comparing this image and the color breakout to mine. I'll take a fresh and hard look at it tomorrow.

I do hope that all will be well on correction...

Close up of evaluation and problem

Full Schematic

Words to the wise:
I actually made another mistake. As I was confident after spending so much time on it I did not go back and double check.

Fortunately I am now very comfortable soldering I will be able to correct pretty quickly.

Let me know what you think or if you see anything else I might have missed. Thanks for pointing me in the right direction!

John