[rob2290]

Hello fellow machine builders and CNC'ers.

I am building a heavy 5x10 CNC Router / Mill that is coming along very nicely and is almost finished. I just need to finish up installing and configuring the electronics, and also finish the Z-axis.

I am using 3 axis of DMM Dyn4 drives (seems like i'm one of the few using the Dyn4) with the 1.3kw servos on all axis, Z axis has the brake option installed. It is a reasonably heavy machine which will have a large spindle, hence why I chose 1.3kw servo's all around. On the controller side I chose to run a Mesa 7I77 setup with LinuxCNC.

I have just about all the electronics wired and configured and I am getting the servos to spin (in analog mode) and encoders are reading correctly in LinuxCNC. Although the servos are not yet tuned, they are responding to LinuxCNC and all is fine with regards to that.

The issue I am having and can not seem to figure out is what I am doing wrong when is comes to disabling the drives, drives seem to be enabled at all times which is undesirable. The drives are normally enabled and require a disable signal from controller, the 7I77 uses a enable signal output which I had to reverse the logic using a N/C relay. 7I77 is responding correctly to LinuxCNC and the relay logic is working as should but I still can not get the drive to disable.
Dyn4 JP4 connector Pin 3 is Disable IN Active high and Pin 16 is 24VDC IN. Should Pin 3 be a negative from psu or positive? Where would the negative from 24VDC PSU connect?
I attached a diagram...

Attachment 281586


Any help is greatly appreciated! Thanks!
Rob

[alan_3301]

[rob2290]

Hi Alan, good to see you are also on here... Just recently found this DMM specific sub-forum and thought I should post my questions on here as well.

Thanks for correcting the diagram, I initially wanted to wire the enable pin3 to neutral but was unsure if the polarity was correct, since, as you know, the manual lists pin 3 as active high which confuses me a bit since I always believed active high needs to be a positive voltage, active when high (as you can probably tell semi conductors are not forte).
I'm at the machine right now and I'll wire it up like in your diagram and see how it goes.

I'll get back asap.

Thanks.

[PCW_MESA]

One note: the 7I77s enable output can be used to drive small relays (50 mA max) but a flyback diode across the relay coil
must be used to protect the Opto-isolator transistor (make very sure you get the diode polarity right = Cathode/Band to +24V side)
Alternatively you can use one of the 7I77s field outputs instead of the ENA output to drive the relay. This will require a change in the HAL file
to connect the field output to the motion enable pin, something like:

net motion-enable axis.0.amp-enable-out hm2_5i25.0.7i77.0.0.output-00

[rob2290]

One note: the 7I77s enable output can be used to drive small relays (50 mA max) but a flyback diode across the relay coil
must be used to protect the Opto-isolator transistor (make very sure you get the diode polarity right = Cathode/Band to +24V side)
Alternatively you can use one of the 7I77s field outputs instead of the ENA output to drive the relay. This will require a change in the HAL file
to connect the field output to the motion enable pin, something like:

net motion-enable axis.0.amp-enable-out hm2_5i25.0.7i77.0.0.output-00

Hi PCW, Thanks for the all the very important information
At the moment, for testing purposes, I am activating the coil manually with the 24v psu for this exact reason as I did not want to damage the 7i77.
The relay I am using is rated at 20mA so I suppose it will be okay to drive with the 7i77 if all wiring is done correct and install a flyback diode... But quite possibly I'll resort to using a field output as it is the safest choice.

Thanks.

[rob2290]

Well seems like I've tried it all and still the drive will not disable. I've swapped drives with a brand new one, swapped i/o cables, checked every single connection and all pins with voltmeter about a dozen times... I don't know what is left to do, or what I am missing, will send DMM a email. Honestly it is probably something simple that I am overlooking but I just can not seem to find the problem

Maybe I'll just design a circuit to disable the power to drives when there is no watch dog signal present... although I do not want to cycle power on and off too often which is why i'd still prefer to get the enable/disable signal working.

Hopefully DMM can enlighten me with a proper wiring diagram or explanation of the wiring in more detail... we will see i guess.

Any other suggestions will be greatly appreciated. Seems like this is the only issue so far holding me back from making progress and finishing up the machine.

[mactec54]

rob2290

This is what the wiring needs to follow, it's good to use a solid state relay, like ( opto 22 ) as well, no noise to worry about

[rob2290]

(This is a re-post from my original thread on linuxcnc, in case anyone here is looking for a answer to the issue)

Seems like I got this issue figured out... Tested pin 15 as a enable pin and that surely did the trick.
Just as I was about to post the fix I received confirmation from DMM tech support in a email.
Thanks to Aidin at DMM for clearing things up... I hope he won't mind me posting the email reply on here as It sure will help any future Dyn4 users get going and set up quicker.

" Hi Robert,

It took us a while but we figured out it is a small change in the firmware for the drives for the Disable. There was a new firmware for the DYN4 drives released earlier last month that had the disable pin incorrectly set to Pin. 15 instead of Pin. 3. Pin. 3 is the pin outlined in the manual and initial requirement, but it was temporarily changed to Pin. 15 to test for develop I/O and was left there by mistake. So currently on the drives, Pin. 15 is the disable and Pin. 3 is not connected NC. This firmware was incorrectly migrated to our production QC software so it wasn't picked up at production.

So basically to disable the drive (using internal power) you will need to connect:

(1) Pin. 17 to Pin. 4 (provide +14V power)
(2) Pin. 15 to Pin. 1 (to activate disable to disable servo loop and motor shaft open)

Or using an external +24VDC power supply: connect positive terminal to Pin16 and connect Pin15 to the relay or negative terminal of your power supply.

Please note that this process will disable the servo loop and once the servo is in disable state the drive will ignore all input movement commands and the motor shaft will be FREE. If your requirements is to not allow any servo movement to be made, you should simply not input any command and the motor shaft will be LOCKED in normal servo operation!

Please let me know what you think.

Regards,
Aidin "


So things are good to go and working on my machine... just a couple steps closer to finishing the machine.