Simpson36
When using Analogue command the drive is basically being used as an amplifier, the CSMIO/IP-A looks at the encoder feedback and decides how much voltage to send to the drives analogue command input to maintain the correct position/speed/time.
Hood
Yes, I can see now from the 'response from CSMIO' posting that they are taking the encoder echo off the drive. The drive is going to be in the loop so there is potential for conflicts. In applications where the servo motor might be mechanically locked, the Mitsu has a specific feature to prevent faulting (the IP-A would continue to ramp up the juice because it does not see the encoder count changing). Eventually (generally within a few seconds) this escalates to a fault. If there will be a locked axis condition, the solution is found in the PC (proportional Control) feature. That's a pretty big topic, so I won't go into it unless someone needs it.
General notes for the user RE: echoed encoder data
Be aware that the encoder output of the drive is configurable in the parameters so that must be addressed. Like step multipliers on the step/dir side, there will be a default value and the drive is going to use that value so it cannot be ignored.
Presumably the IP-A also will require configuration to tell it how to relate encoder counts to movement (pulses per inch, or equiv). Probably you will also need to pay attention to the speed at which the IP-A can take in the encoder data. This should be one of the specs. If you exceed the input capabilities, there is no 'standard' reaction. Each device is different. A J2S for example, will simply stop. It occurs to me that analogue input would not have this issue at all, so advantage analogue.
The basic calc is to determine your maximum motor speed and select an encoder output count that is as high as possible without exceeding the IP-A's read speed . . . with some margin for safety. The Mitsu electronics are uber fast and for example a J3 has over 200,000 counts PER rev encoder. Multiply that by 6,000 RPM and you get a very big number that will overwhelm most devices. The J2S is not as high, but still can outpace a lot of, if not most, typical CNC stuff.
Also, and this presumes the IP-A takes in differential signals, be sure to use shielded twisted pair cable. The 'Z' designator on the diagram indicated a twisted pair. It is important to have the two wires from a pair on the same signal. Don't mix things up. It is best to use cable that has both a foil shield and also a braid shield and if possible, with each pair separately shielded in foil as well. If the IP-A inputs are anywhere near as sensitive at the Mitsu, you will benefit from the extra expense of fully shielded cable.
To avoid creating a ground loop. connect only one end of the cable shieling to the device ground. Unless there is a compelling reason not to do so, I would ground the shields to the IP-A and check for lack of continuity at the drive is you use shielded connector or better yet use an unshielded connector at the drive to eliminate the possibility of accidental contact between the cable shielding and the drive ground.
I know this is 'CNC Wiring 101' stuff, but perhaps it will be useful to nubees who may read the thread.