Does the error repeat exactly each time ??

I would try calibrating the encoders to MACH3    Move a certain distance (exactly) then calculate the encoder steps required to do so. TEST then adjust till exact . OR as close as you can get based on the encoder and MACH3s steps per unit .

MACH3 is not known for errors in its math channels (;-)

IF the error does not repeat exactly each time then that is another problem.

(;-) TP

Double check your part # and pulses per.
The data sheet doesn't show a 1000 (4000 quad) pulse.
There is a 250 (1000), and 240 though.
I'm guessing the count values are not set appropriately in Mach.
Russ

TP, The error is usually close but not 100% exact all the times. I thought about trying to adjust the ppr setup. Right now is setup in 800 and using something like 803 doesn't sound like a proper way to solve it. Anyway, the error is not exactly the same all the times.

RUSS, I know what you say and I saw it when I ordered the encoders. The encoders are HE50B-8-1000-3-T-24, so based on the model # they are 1000 ppr and that's what I ordered. The only thing I missed when I ordered was to try 5v instead of 24v. Now I put a BC547 transistor on each signal to adjust form 24v to the 5v I need at the board input.

The board I'm using to interface with the LPT uses a 74HC244P to isolate the LPT from the machine, although I don't think this could be causing a problem.

Just as a test, as in your first post.
Start at 0, manually move 400 then back to 0 several times. Does more error accumulate ?
Or is 0 always 0 ?
One would indicate noise, the other calibration.
Just curious,
Russ

No, the error accumulates. If i MDI from 0 to 400 and back to 0 the encoders don't show 0, although the won't show everytime the exact same number.

I think you have a problem in your Circuit to adjust your signals probably a noise issue.

The encoder will replicate the exact signals each time and MACH3 will interput them exactly each time so the error SHOULD replicate itself exactly each time


Just a thought, (;-) TP

You might also run the MDI test at dramatically different speeds to see if that reports differently.
Could there be a possibility that there is "chatter" in the movement ? This could cause some pulses to duplicate making the count go up for a given move ?
Is the stepper direct coupled to the screw ? Or belted ?

Don't know how encoders work with PP, but did you try playing with the debounce setting? I tend to agree with Terry that there is some problem with your circuit., picking up noise.

Dan

I do believe as well it may be noise. I had noise issues testing my probe, so this could be happening here too.
with the probe I put a couple capacitors across the input and that worked as a charm, although I can't do that here since the capacitor would mask the pulses. With the probe is ok because there I don't expect a pulse train.

How can I filter the noise in this case?

I tested at VERY LOW and VERY HIGH speeds and I still get errors in both cases.

I also played with the debounce and no luck.