Koike Aronson Plasma Conversion - sanity check on Mesa board selection?

Please note that the signal in the drive P1 connector is inhibit, so when the input floats the drive is enabled. This means that in order to disable the drive, you need to provide 5V (from P1 #1) to P1 #11.
For a machine like that, I would just wire a single ”enable” to the drives. Either use the existing relay (most likely NC contacts between P1 #1/#11) or reverse the logic in lcnc.
Relay probably better so that drives are disabled when there is no control to the relay.

RDA wrote:

Please note that the signal in the drive P1 connector is inhibit, so when the input floats the drive is enabled. This means that in order to disable the drive, you need to provide 5V (from P1 #1) to P1 #11.
For a machine like that, I would just wire a single ”enable” to the drives. Either use the existing relay (most likely NC contacts between P1 #1/#11) or reverse the logic in lcnc.
Relay probably better so that drives are disabled when there is no control to the relay.
 

I did this on my recent mill conversion.  I set up a 3-pole double-throw relay that was activated by the E-stop circuit.  The relay's NC contacts make the disable connection.  When the relay is energized by the control coming out of E-stop, those contacts open and enable the servo amp.  The 3 relay poles make sure there are no connections between the separate servo amps that could cause some crosstalk.
Jon

Thanks for the replies, I should have noted the inhibit logic on the drive itself in my earlier post, but from my interpretation of the datasheet for the 12A8, GND at the input would disable the drive.  Is that correct?
11 INHIBIT IN TTL level (+5 V) inhibit/enable input. Leave open to enable drive. Pull to ground to inhibit drive. Inhibit turns off all power devices.

If so, I would just connect direct to each servo drive with a ground wire connected to the following pins below on the mesa board and then the other side of the floating switch would also go to GND:  
net joint-0-enable joint.0.amp-enable-out => hm2_7i97.0.ssr.00.out-00
net joint-1-enable joint.1.amp-enable-out => hm2_7i97.0.ssr.00.out-01

Alternatively, if I could figure out how to make those into one signal with OR'ed logic for turning ON and AND logic for turning off, I would just drive the 12V relay on the board with one output, however, the Estop approach may be the simplest one to implement when reusing the existing PCB.  

I'm assuming the Mesa board / LCNC don't care if anything is connected to servo enable as long as the motors move when commanded?  Meaning if the servos were enabled externally via Estop for example, the motion control would still work just fine and I could leave out the above two net commands from the HAL file?

I am terribly sorry about saying the inhibit being pullea high, I opened the manual and you are correct, its low.
Like you said lcnc will not have a feedback for the enable signal itself from those drives, it just assumes they enable when commanded.
Go with the e-stop approach or use one output to turn on/off the existing relay.

No worries, thanks for the confirmation!