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Cant home or move motors "DMM DYN4" (Resolved)

Posted: Sun May 30, 2021 10:28 am
by Eric S
Hi All! Just finished installing new Dyn4 Servos and Drives. I'm using oak and haven't been able
to get my motors to turn or enter the MDI screen without it kicking me out.
I have green lights on all my drives "on position" in DMMDRV software. I've set all to A/B phase, precision mode
active low and 2000 for both gear number and line number within the software.
I've got it all wired correctly including my oak to DMM cables with drains on both Db25 and DB9 to oak.
I think the issue is within the parameters of Oak somewhere. I have 256 set to precision mode, made sure that encoder counts are
8000 in CNC12. I'm trying to get the precision mode delay tuning screen to come up, but since I cant home that isn't and option
for me. Not sure what I might be missing. My question is: does cnc12 require my spindle/ a few of the other board
components before I can get the MDI screen to come up and activate the drives for motion?
Spent a good while double checking all my connections and settings and I'm stuck.

Thanks for the help. Here's a current report:

Re: Cant home or move motors "DMM DYN4"

Posted: Sun May 30, 2021 11:41 am
by lavrgs
Can you move your axes with the virtual control panel? Have you looked at the diagnostic screen? >>ALT I
Do you you have a door open that is triggering a fault? Did any of the axes move when bench testing? Can you set the machine to HOME? I'm not sure MDI will work before the machine is homed but the VCP should work. Sorry for the shotgun approach - hopefully the experts will chime in

Re: Cant home or move motors "DMM DYN4"

Posted: Sun May 30, 2021 5:29 pm
by martyscncgarage
Are you following this information from DMM?
Are you following the Centroid Oak Installation manual step by step?
Did you make up your OWN signal cables or did you buy the OAK/DYN4 cables from DMM?

Re: Cant home or move motors "DMM DYN4"

Posted: Mon May 31, 2021 2:12 am
by ashesman
I have the same setup and besides some other unresolved issues, found that as long as all the faults were cleared that the axis would move on the jog panel. I think if any faults are active, the Oak disables the drives.

Also important to set the DYN4 drives to active low enable as per the pdf Marty attached. Make sure to store the settings, cycle the power to the drives and load them again to check. I had recently had a bad firmware version that would not store the active low setting permanently.

Someone can correct me if I am wrong, I dont think the gear num and line num values are correct in that pdf. I asked DMM and they assured me they were. I think they should both be the same value. I am about to go do some experiments to confirm this.

Re: Cant home or move motors "DMM DYN4"

Posted: Mon May 31, 2021 6:23 am
by ashesman
So I did some testing by trial and error tonight and found the following:

The Oak expects to receive the same number of pulses for one revolution of the motor as it sends out (assuming encoder on motor). DMM say to set the Oak to 32678, GEAR_NUM to 8192 and LINE_NUM to 4095. This is correct for the oak driving 8192 x 4 = 32768. But, the encoder output signal would be 4095 x 4 = 16380. The correct numbers to use are Oak = 16380, GEAR_NUM of 4095 and LINE_NUM of 4095. output pulses = 4095 x 4 = 16380 = 4095 x 4 = input pulses. 4096 can not be used for GEAR_NUM as you cannot set LINE_NUM higher than 4095. You would lose 4 pulses per revolution.

Ideally you would set the number of pulses per revolution to encoder counts per revolution, which in my case is 10000. That would give GEAR_NUM = LINE_NUM = 2500. GEAR_NUM of 2500 works correctly. When I tried, it turns out that even if you set LINE_NUM to 2500 it doesn't work. The DYN4 always outputs 4095 x 4 = 16380 pulses. But that could be because I am using DMM encoder adapters too.

Re: Cant home or move motors "DMM DYN4"

Posted: Mon May 31, 2021 8:19 am
by martyscncgarage
I use 2000 for both the yes and lin number values in DMMDRV and 8000 in CNC12 Is encoder counts. I didn't agree with DMM either on this issue...it worked for me

Re: Cant home or move motors "DMM DYN4"

Posted: Mon May 31, 2021 1:36 pm
by cncsnw
I am pretty sure that a LINE_NUM value of 4095 is what software people call a "sentinel" value: one that has special meaning, different from its face value.

I think the intent is that LINE_NUM = 4095 acts like 8192, but gets around the value limitation.

Whether it works right, and whether it works right with the firmware in your particular drives, is another question entirely....

Re: Cant home or move motors "DMM DYN4"

Posted: Mon May 31, 2021 3:17 pm
by ashesman
4095 is the highest number you can fit in a 12 bit variable. It is used as its actual value. The real encoder counts out of the motor drive will be 4095 x 4 = 16380.

Just dont use a number in the oak that is less than the number of pulses your encoder has or you are losing precision.

Re: Cant home or move motors "DMM DYN4"

Posted: Mon May 31, 2021 5:38 pm
by Eric S
THANKS GENTS so much for all the replies!!! I always appreciate you guys taking the time to help me out.
Yall are a bunch of awesome people.

Here's what the issue was:

I hadn't yet applied 24 volts to my H2 terminal on Oak and this is what was causing my error. Such a small stupid thing to overlook but its cost me a good amount of time trying to troubleshoot. Hook up your H2 terminal with 24Volts!!! :x

For the record the video DMM has on setting up the drives is correct. The line number and counts can both be set to 2000 I'm getting good motion with no error. The settings in the video they show are perfect: set to A/B phase and precision mode with active LOW and then tune as needed. A word of caution: Save yourself the time and headache and buy your Oak To DMM cables from DMM. Its worth the money time and potential issues you can cause yourself. There's a myriad of trouble you can run into if these cables aren't wired shielded and grounded perfectly. I consider myself a decent retrofit cable maker at this point and these got tricky quick.

I've now got good motion on my X,Z and A axes. DMM customer service has been amazing. Ill get some pictures posted up soon of the Horizontal rebuild. She's gonna be a metal muncher.
**RESOLVED**