What is indexed and interpolated? Indexed I am sure is move forward
The term "index" in the motion world is a type of move where the servo motor takes a position command, velocity command, max accel, and max decel and moves using that profile one time. It also applies to "Absolute positioning" and "Incremental positioning".
Absolute = A position command referenced from a homed position (usually zero).
Incremental = A position command referenced from its current position.
So if your servo was looking at a tape measure and it was sitting at "zero", and the servo was in absolute mode.
If you told the servo to go to 24", the servo would go directly to 24" and stop. If you told it to go to 13", it would reverse and go directly to 13". The motion planner knows that 24" is greater than its current position, so it knows to go forward. The planner knows 13 is less that 24, so it reverses to go to that position.
So now say your servo is in incremental mode.
Starting with your servo at zero, you tell it to go to 24". The servo will move 24" then stop. So far so good right? Then you give the same command of 13", the servo will then move another 13" in the same direction. Now the servo is at 37".
In this mode, the planner does not care what position command you give it. All it cares about is in what direction it should make the move and how far it should go. You do this by giving it a positive command (forward) or a negative command (reverse).
So, your servo is sitting at 37". You give it a command of -13, the servo will then subtract 13 from its current position of 37 and return back to 24". If you gave the same -13 command again, the servo would be at 11".
All of these moves are considered "indexes".
Interpolated is a mixture of moves or indexes being done by two or more servo drives. One of the servos being a master and the others being slaves.
Think of two trucks, truck #1 is traveling down an interstate at 70MPH and truck #2 is approaching an on ramp at 40MPH. The trucks need to meet at the merging lane at the exact same time. Their speed needs to be interpolated or communicated in order for truck #2 to meet with truck #1 at the merge lane. Where truck #1 will not change speed, truck #2 will speed up on the on-ramp to catch up to truck #1.
If you want more tailored info and can share, let us know what kind of servo motion you are looking at. Will it need to just index back and forth? Or, will one servo need to know what the other is doing so they dont crash?