acorn and dmm dyn 4 losing steps

[cncman172]

Jerry,
Never thought you were an idiot. Well probably are all a little crazy building our own machines, but I have always found it enjoyable, because as you build it and make it work that kind of instant feedback is just amazing.

Post a shot of your current control cabinet, maybe someone will spot a potential issue. As Marty pointed out others have the Acorn with those drivers and they work, so you might have an AC power source too close to the Acorn or something.

Russ

[fozzyber]

Thermwood acorn / Dmm controller

[cncman172]

This is helpful. Take a close look at your AC power coming into the L1, L2 connections they appear to be Black and White. If you notice those AC lines are running right next to and in a few cases touching the control signals. You need to move the control cables to the far left and keep them as far away from 120V AC as possible. This is absolutely cause interference.

You can do a quick test and probably confirm my suspicion.

Russ

[cncman172]

I drew some red circles around the areas of concern. That AC noise will absolutely impact the Step and Direction signals flowing through that black cable even with shielding. Route the black cables away from the AC power and your issues might be gone.

Russ

[fozzyber]

made changes to wiring. , and it is a bit better, but servo still moves when it should not if DMM cable shield is ungrounded. It is also losing steps but not as much if shielded.
diff. line drivers just came in going to try that..

[fozzyber]

CORRECTED DIFF LINE DRIVER AGAIN, I redrew the ground to com wire.

[cncman172]

Remember to wire the pull up to 5Vs, some of the differential driver chips can not accept being pulled up to 24V. 5V will work fine.

Or if you want you can take the signals from the Parallel port for Step and Direction and you will not need pull up resistors at all.

Russ

[fozzyber]

wait I thought you told me to do the pull ups to 24v????? do the pull up resistors go to 24v or 5v? or am i missing something here?

"close you did the pull up resistor much closer but they must pull up to 24V on Acorn not 5V like you have them drawn.

Remember to wire the pull up to 5Vs, some of the differential driver chips can not accept being pulled up to 24V. 5V will work fine.

Or if you want you can take the signals from the Parallel port for Step and Direction and you will not need pull up resistors at all.

Russ

[cncman172]

fozzyber,
There are different manufactures for those differential ICs. Some can handle the higher voltage but many will not. To be safe pull them to 5V. If you do not want to use pull up resistors then use the signals on the Acorn DB25. Those step and direction signals already have pull ups. That is actually the signals I use except for the enable signals which I get from the screw terminals.

Sorry for the confusion. Another engineer reminded me of this issue in another post. Ugh

Russ

[fozzyber]

this is the signal out put from the pul ( stepS) from the acorn. as the motor spins CW it gives a signal of 24v but when it turns CCW the signal goes to 5v.. is this correct???

https://youtu.be/jNdwG2EHUZE
https://www.youtube.com/watch?v=jNdwG2EHUZE