While I have not set up a Mitsu for analog, I am familiar with them and might be able to clarify a couple of things.
SON (Servo On) which I also refer to as Enable , must be grounded to SG (Signal Ground) to enable the Drive. Depending on what the servo is used for, it may or may not be useful to use this signal rather than just tying it off to ground. For example of a lathe head or mill spindle, you will want to disable the drive in order to have the spindle freewheel.
EMG (Emergency) vs ALM (Alarm): EMG is an E-Stop TO the drive. This should be permanently grounded since MACH takes care of E-stopping drives.
ALM is the drives 'Fault Line' and is connected to MACH E-stop
The Start/Stop and Limits seem to be intended for continuous running until a stop (limit switch) is encountered. Both limits should be grounded (i.e. the limit switched have not been hit) and I *think* both starts should be open. Direction of rotation is configurable in the drive's parameters.
P15R and LG are a special isolated pair (power) for analog pots that set limits on speed, torque, etc. They are not signals.
I *think* you only need VC as the analogue input signal. Again, I have not done a Miitsu with analog and all of the above is from memory. I have the full Mitsu manuals is anyone needs them.
Important notes:
The Miitsu is 24V interface. The J2S has its own 24V internally and normally the signals are ON when grounded to SG , but this is configurable, so make sure it is set this way if that is how you wire it up.
Specifics:
Signal Grounding:
I have a lot of experience with the Mitsu and while it is not made particularly clear in the manuals, the power side and signal side of the drives are isolated and should stay that way. Grounding the Mistu signals back to the Mitsu is the most reliable way to run them. If you ground a signal to the power side of the drive, to your BOB, motion controller, a chassis or any other ground, you may experience a lot of spooky problems like the motors mysteriously creeping all by themselves.
I recommend running the Mitsu signals thru an Opto or SSR back to the Mistu SG. Use your BOB to trip the Opto or SSR.
Mitsu Outputs:
Mitsu outputs have no current limiting so they are very easy to fry. If you connect the output directly to BOB or other device without current limiting of some kind, you will fry the output and possibly the BOB or motion controller as well. There are ways to test your BOB or other device to see is it has current limiting and what it is limited to, but that's a different discussion. I find it safer and more reliable to run the drive signals thru isolators to eliminate any possible damage.
I recommend running the outputs by taking 24V power from the drive, running it thru a 400 Ohm power resistor and then using the resulting power thru appropriate optos or SSR back to the Mistu Outputs. Take the signal for your BOB, motion control or whatever off the Opto or SSR.
There are a lot of ways to design an interface scheme, but the overriding requirement is to limit the current you run thru the Drive's outputs.