User's Manual

PMAC User Manual
40 Troubleshooting
If the motor dies after it is given a jog command, the fatal following error limit has been exceeded. If this
has happened, it is either because a move that is more than the system can physically do has been
requested (if so, reduce I122), or because it is badly tuned (if this is the case, increase proportional gain
I130). To restore closed-loop control, issue the J command.
Homing Search Troubleshooting
No Movement at All
Check the following:
• Are both limits held low to AGND and sourcing current out of the pins?
• Is there a proper supply to A+15V, A-15V, and AGND?
• Is the proportional gain (Ix30) greater than zero?
• Can any output be measured at the DAC pin when an O command has been given?
• Is the following error limit being tripped? Disable the fatal following error limit (Ix11) by setting it
to zero, and try to move again.
Movement, But Sluggish.
Check the following:
• Is proportional gain (Ix30) too low? Try increasing it (as long as stability is kept).
• Is the big step limit (Ix67) too low? Try increasing it to 8,000,000 (near the maximum) to eliminate
any effect.
• Is the output limit (Ix69) too low? Try increasing it to 32,767 (the maximum) to make sure PMAC
can output adequate voltage.
• Can an integrator help? Try increasing integral gain (Ix33) to 10,000 or more, and the integration
limit (Ix63) to 8,000,000.
Runaway Condition
Check the following:
• Is there feedback? Check that position changes can be read in both directions.
• Does the feedback polarity match output polarity? Recheck the polarity match as explained above.
Brief Movement, Then Stop
Check the following:
• Is this following error limit being tripped? Disable fatal following error limit (Ix11) by setting it to
zero, then try to move again.
Motion Program Troubleshooting
If the program does not run at all, there are several possibilities:
• Can the program be listed? In terminal mode, type LIST PROG 1 (or whichever program), and see
if it is there. If not, try to download it to the card again.
• Is the program buffer closed? Type A just in case the program is running; type CLOSE to close any
open buffer; type B1 (or the program #) to point to the top of the program; and type R to try to run it
again.
• Can each motor in the coordinate system be jogged in both directions? If not, review that motor's
setup.
• Have any motors been assigned to the coordinate system that are not really set up yet? Every motor
in the coordinate system must have its limits held low, even if there is no real motor attached.