Could someone please provide an optimal code example to issue a Position Absolute or Position Relative command to the X-Axis servo motor based on the positioning of the X-Axis auxiliary encoder? II don't see anything in the command set to directly issue such a command.
Using CDS-3310.
KushalP on 07/26/2017 - 17:19
Hi renniejohnson,
Are you using the aux encoder feedback as your primary encoder feedback? Or is your Aux encoder user used in a dual loop configuration?
The Aux encoder position is reported by the TD command. So to command a move based on the position of TD:
PRA=_TDA ;' This would be a position relative move that is equal to the current position reported by the aux encoder
PAA=_TDA ;' This would be a position absolute move that is equal to the current position reported by the aux encoder
You would issue a BGA after each of those move commands
renniejohnson on 07/26/2017 - 18:31
Hi, Kushal.
There is no dual loop setup. Drive motor is a round polyurethane capstan driving motion picture film. The auxiliary encoder is connected to a follower film sprocket which provides absolute film positioning, as it has a known number of frames per revolution. This is a single axis system, as tension take up is handled with a separate servo system. Drive servo motor's encoder is connected to the main encoder input. The follower sprocket is connected to the auxiliary encoder, which is wired to the Galil auxiliary encoder input.
I'm not sure your example code is exacly what I want to do. Here is an example:
1. The servo motor encoder has 20,000 counts per revolution.
2. The auxiliary encoder has 2,000 counter per revolution.
3. The current position of the auxiliary encoder on the load is 0.
4. The current position of the motor encoder is irrelevant, as I only want to make moves based on the auxiliary encoder position.
5. I want to issue a POSITION ABSOLUTE command to move the auxiliary encoder to a count of 400.
6. I want to issue a POSITION RELATIVE command to move the auxiliary encoder +400 counts.
The encoder count of the main motor is never of concern to me, as the motor only moves the film forward and backward. All positional information I use is from the auxiliary encoder on the load.
I don't want to use dual loop mode, because I don't want to introduce instability, or make tuning difficult.
Thanks,
Rennie