Another DYN4 and Acorn Losing Steps Issue

[martyscncgarage]

I am going to test the issue on my Emcoturn 140 using the method that Arrow Controls used. Issue is I'm under the weather, I'll see how long I last today.

Steven try and drop the pulse frequency to 200K and retest.

Marty

[slodat]

I am going to test the issue on my Emcoturn 140 using the method that Arrow Controls used. Issue is I'm under the weather, I'll see how long I last today.

Steven try and drop the pulse frequency to 200K and retest.

Marty

I lose less encoder counts at 200khz. But still losing them.

I have a DB9 flying lead cable I could do the same, been using the encoder read thus far.

[cncman172]

Check in another posting about a guy having the same issues, who posted this morning. He failed to put on a ground and as soon as he did it fixed his issue.

Russ





cut2cut » Mon Feb 25, 2019 10:36 pm
Add a ground jumper from either the DYN4's DB9 (JP5) or DB25 (JP4) nut to the ground terminal on the DYN4. See enclosed picture, the nut is partially obscured in the picture. The black wire with red arrows pointing to the connection points. I am fairly certain your issue will vanish.

p.s. hopefully this topic becomes a sticky.

Jake

[cut2cut]

I’m wondering if the problem is the 2k pull down resistor in the DMM DB25 cable shares between the step and direction circuits not pulling down enough for both? Or the 24v screw terminal connections vs 5v db25 connections?

I sincerely appreciate the help, I obviously need it.
Thank you!
Steven

If you have some good shielded Cat 7 cable ( used for ethernet cabling ( Cat 7 has the best shielding I believe ) and a male DB25 connector you could test the above pretty easily by whipping up a cable using this wiring diagram. ( keeping the twisted pairs as diagramed for shielding purposes )

Note the red 24 vdc supply wire for the Dyn4 is external ( added ) and separate of the ethernet pairs , also, I have a BKO/brake wire that most people won't need, its for a Z axis brake.

It is what I'm using, but I haven't tested it thoroughly. I have a bad ball screw that has really stopped my progress, among other things, however I am not trying to achieve nor could I test 800ipm on my "little" 3 axis metal mill.

Cheers,

Jake

[cut2cut]

alternatively, if someone doesn't have resistors on hand and wants to experiment, apparently this was an early method of wiring the DYN4 to Acorn.

Maybe someone can jump in and explain why it isn't used anymore ?

I got this from someone that said it worked fine for him for over a year but he may not have tested it for lost steps ? Dunno... but the beauty of it is that it uses the DYN4's internal 5v power supply negating the need for the resistors and making a fairly simple cable. It does tie the grounds together which may solve the lack of shield grounds ? perhaps ? Its possible the DYN4's internal 5v power supply has limited capacity ( 50mA ) thus the reason for going away from it ? Not sure, but here is the diagram for the adventurous :

Cheers,

Jake

[slodat]

Is there a reason you couldn’t use Acorn’s +5vdc on pins and 11?

[slodat]

Did some more testing. The only thing I changed is put +5vdc on the brown wire of the DMM cable on the drive side of the 2k resistor (bypassed it). Still losing steps. Here is some data:

[slodat]

Same tests, this time with +5vdc on the brown wire of the DMM cable and step and direction from Acorn DB25 pins 2/3.

Encoder counts are not being dropped. There is an issue with the screw terminal outputs being used with these DYN4 drives.

[cnckeith]

i know this doesn't help your dyn4 issue...but i just have to throw this out there..... centroid sells Estun 400 watt and 750 watt AC brushless motor/drive/cable packages as an alternative to DMM
these have been on our in house router now for quite some time with no issues.

[slodat]

My last test. I feel like this is conclusive.. The issue is the screw terminal outputs are not compatible with the DYN4 drive.

I doubled the GEAR to 4096 and corresponding steps/rev to 16,384. This is the results, using the DB25 step/direction outputs.

These tiny error numbers are insignificant. The largest error 26/65,536 of one revolution of the motor. On my machine that is about six tenths. The important thing is the absolute position error doesn't increase the more times it moves.