Delta Tau PMAC Mini, Reference Manual

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PMAC Quick Reference Guide
Troubleshooting 69
Bus Communications
1. Do the bus address jumpers (E91-E92, E66-E71) set an address that matches the bus address that the
Executive program is trying to communicate with?
2. Is there something else on the bus at the same address? Try changing the bus address to see if
communications can be established at a new address. Usually, Address 768 (300 hex) is open.
Serial Communications
1. Is the proper port on the PC being used? Make sure that if the Executive program is addressing the
COM1 port, the COM1 connector has been cabled out.
2. Does the baud rate specified in the Executive program match the baud rate setting of the E44-E47
jumpers on PMAC?
3. With a breakout box or oscilloscope, make sure there is action on the transmit lines from the PC
while typing into the Executive program. If not, there is a problem on the PC end.
4. Probe the return communication line while PMAC receives a command that requires a response
(e.g.
<CONTROL-F>
). If there is no action, change jumpers E9-E16 on PMAC to exchange the
send and receive lines. If there is action, but the host program does not receive characters, RS-232
could be receiving circuitry that does not respond at all to PMAC’s RS-422 levels. If there is
another model of PC, try using it as a test (most models accept RS-422 levels quite well). If the
computer will not accept the signals, a level-conversion device, such as Acc-26 may be needed.
Motor Parameters
1. No movement at all. Check the following:
a. Are both limits held low to AGND and sourcing current out of the pins?
b. Is there proper supply to A+15V, A-15V, and AGND?
c. Is the proportional gain (Ix30) greater than zero?
d. Can any output be measured at the DAC pin when an O command has been given?
e. Is the following error limit being tripped? Increase the fatal following error limit (Ix11) by setting
it to a more appropriate value, and try to move again.
2. Movement, but sluggish. Check the following:
a. Is proportional gain (Ix30) too low? Try increasing it (as long as stability is kept).
b. Is the big step limit (Ix67) too low? Try increasing it to 8,000,000 -- near the maximum -- to
eliminate any effect.
c. Is the output limit (Ix69) too low? Try increasing it to 32,767 (the maximum) to make sure
PMAC can output adequate voltage.
d. Can an integrator help? Try increasing integral gain (Ix33) to 10,000 or more and the integration
limit (Ix63) to 8,000,000.
3. Runaway condition. Check the following:
a. Is there feedback? Check that the position changes can be read in both directions.
b. Does the feedback polarity match output polarity? Recheck the polarity match as explained
above.
4. Brief movement, and then stop. Check the following:
a. Is the following error limit being tripped? Increase the fatal following error limit (Ix11) by
setting it to a more appropriate value, and try to move again.