Another DYN4 and Acorn Losing Steps Issue

[cut2cut]

Question, which cabling did you use from the DB25 ? Could it be a shielding issue due to using different cables ?
Just checking...

Jake

[slodat]

Question, which cabling did you use from the DB25 ? Could it be a shielding issue due to using different cables ?
Just checking...

Jake

My opinion, based on my testing and my experience in my profession.. this is not a noise issue. At all. The only thing I changed is moving the step/direction from the screw terminals/+24v to the DB25/+5v. Doing that, and that alone and I'm not losing encoder counts anymore and I'm at 16,384 steps/rev. I'm pretty sure this was the problem I was having with my Yako steppers losing steps, too. But, I didn't have an encoder to help isolate the issue.

This is the DB25 breakout board I'm using. I am plugging this directly into the DB25 connector on Acorn. I'm using DMM's DB25 flying lead Acorn connection cables at the DYN4.

Connections:

Brown - +5vdc (I bypassed the 2k resistor built in to the cable)
Green - Acorn DB25 step
Blue - Acorn DB25 direction
Orange - Acorn input5
Black - Acorn screw terminal common
Red - Acorn +24vdc screw terminal
Yellow - Acorn screw terminal enable

[cbb1962]

Slodat,

So now you are at roughly +- 15 counts. What does that translate to in inches? I would guess it is an extremely small number.

Clint

[martyscncgarage]

I don't have the issue you guys are having with any of my DYN4 builds.
I use DMM's DB25 flying lead cable and I have made my own cables.

I just did the "Ruppe" test and posted a video:

https://youtu.be/NQrgwdAZK9s

https://youtu.be/NQrgwdAZK9s

[slodat]

Slodat,

So now you are at roughly +- 15 counts. What does that translate to in inches? I would guess it is an extremely small number.

Clint

Clint,
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 (0.0006")

Correction: 0.00025"

[slodat]

Did some more testing tonight on my X axis, looking to see if I'm losing encoder counts.

The test moves:

Code: Select all

g0x-4
g04 p1
g0x59
g04 p1

Results:

Code: Select all

		Start		After 25	After 50 more
g0x-4		  396092	  396089	  396089
g0x59		-5846136	-5846145	-5846149

After 75 traversals back and forth (63" moves) at 969ipm, largest error was 13 counts over ~9450 inches of travel. Accel/decal is set at 0.2s. This was with my spindle running at 18,000 rpm, varying the speed along the way from the VCP.

My solution was to remove the 2k resistor from the DMM DB25 cable, connect the brown wire of that cable to +5v, and use the Acorn DB25 step and direction outputs.

[Richards]

slodat,
Just so I'm clear (and so I understand how to modify my DMM supplied DB25 flying lead cable). Your Z-axis is running almost perfectly after removing the 2K resister from the flying lead cable supplied by DMM. The Brown wire in that cable on the DMM DB25 connector feeds pins 11 and 22 to the DMM driver. After you removed the 2K resistor, do you now have 5V going to pins 11 and 22 on the DMM DB25 cable with the DMM Green wire (pin 23 on the DMM DB25 cable) connected to an Acorn DB25 step pin and the DMM Blue wire (pin 10 on the DMM DB25 cable) connected to an Acorn DB25 direction pin?

[slodat]

Richards,

In short, yes. I’ll try to add some detail..

My Connections:

Brown - +5vdc (I bypassed the 2k resistor built in to the cable)
Green - Acorn DB25 step
Blue - Acorn DB25 direction
Orange - Acorn input5
Black - Acorn screw terminal common
Red - Acorn +24vdc screw terminal
Yellow - Acorn screw terminal enable

The DMM DB25 cable has a small pcb soldered to the db25. The 2k resistor is through hole soldered on that board between pins 11/22 and the brown wire. I desoldered the resistor and the brown wire. Then I soldered the brown wire in the former resistor solder pad connected to the pins. Thereby making a straight through connection between the brown wire and the pins. I then connected the brown wire to my +5vdc.

[Richards]

slodat,

Thank you!

[slodat]

As the photo shows, this was done on all four axis drives.

It seems disengenuous to have the published schematics and setup guides barked at us when there is clearly an issue with DYN4 connected to the Acorn screw terminals dropping steps. I wasted a lot of time troubleshooting a supposed known working combination.

My machine is now working as expected.