MESA 7I97T+7I76 Mill Setup Advice

Hello,

I'm building my first LinuxCNC project which is a CNC conversion of a Precision Mathews mill using DMM AC Servos and their DYN4 drivers driven in Analog mode.  I am using a Mesa 7I97T and 7I76. The 7I76 will primarily be used for spindle motor control and additional inputs, if I eventually need them.

I am almost complete with wiring the control breadboard for setup and bench testing but I have questions regarding interfacing a MPG Pendant:

1. I see there are firmware files for the 7I97T+7I76, but nothing supporting MPG. 
2. My current layout is to interface the 7I97T MPG A- with TB4 Pin 1 and B- with TB4  pin 2 (+5V to 3), then use TB4 pins as inputs 4 thru 12 as sourcing inputs for the MPG axis and pulse multiplication switches (+24V to TB4 6,9, and 12).  Is this possible while having the card set to support the MPG encoder on TB4?
3. My MPG pendant encoder can be used double-ended. Is that possible on the MESA?

Thanks,

Skylor

2. Yes you can mix The 7I97T MPG input   with other functions
(the MPG encoder counts on the other MPG inputs may change
with the selector switches but they can be ignored since you
are only using 7I97 MPG encoder 0)

3. No the isolated inputs are single ended only

I am learning. I wonder why you would use the 7I76 for the spindle motor control; would the 7I97T not be enough for your needs? Also, 7I76 uses step direction, meaning your spindle uses step direction, not PWM. I am trying to learn as much as possible before starting my build. Please share your thoughts

The 7I76 connector TB4 is configured specifically for analog spindle control which includes a digital pot for speed control as well as enable and direction signals which interfaces well with VFD type inputs. If I were to use a servo with encoder for the spindle, certainly one of the unused analog and encoder channels on the 7I97T would work. The 7I97T also doesn’t seem to have that many inputs, especially when using an MPG pendant, thus I had the 7I76 to add I/O’s to my setup in case I need them down the road.

Skylor

Is any specific software mode required on the 7i97T for the MPG inputs to work? I didn't see any mention of this in the manual.

Thanks,

Skylor

No, they are always there.

Excellent. Thanks! I just put the Hal meter on inmux.00.enc0-count and see that it is in-fact counting when I move the MPG wheel, albeit backwards. I do have noise issues on the TB4 and TB5 inputs that are occurring when the DMM servo drives are powered up, even with the drives disabled.  This doesn't seem to be affecting the motor encoder inputs, however.  I followed all of DMM's recommendations for shielding and noise filtering - but regarding the signal cable shielding they recommend connecting the shied ground the the connector shell at the drive end vs. the MESA manual which recommends shielding at the Mesa end...

Skylor