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