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Synchronised trigger output


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Hi all,


Currently, we obtain a 5V trigger generated using a virtual axis which is synchronised with a moving axis in the same coordinate system. We're obtaining a trigger approximately every 0.5mm that the axis moves.


The trouble is, it is not accurate enough and as speed settings are altered, there are issues with synchronisation. I assume that this is because, despite being in the same coordinate system, the PMAC still treats them independently. Does anyone have any suggestions as to how I could generate a pulse? Perhaps an output every given number of counts?



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Hi Curt and Richard,


Thanks for this. I'm currently trying to set up a position compare output as described in the Turbo PMAC user manual. I've checked I4902 and I4903 for the presence of DSPGATE2 IC. They are $3 and $1 respectively which I believe indicates the presence of 2 IC's, one of which is a DSPGATE2 IC. Do I68n1/I69n1 need to be set?


Using "Position compare examples" and the "Using the Position-Compare Feature on Turbo PMAC" I have established that register:


M108->Y:$078007,0,24,S ; Position compare A value (counts)

M109->X:$078007,0,24,S ; Position compare B value (counts)


However, my motion program is unable to change these from a set value of -1. I have also tried to alter these values manually in the M-Variables but they revert back to -1. I imagine I'm missing something very simple here.


Many thanks

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Sorry, I should also have mentioned that I am using ABB Drives. I fear this may make position compare impossible? Are there any other methods of generating a precise trigger based on the movement of the Y axis? Or, perhaps a method of improving the precision of our virtual motor?
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This feature over MACRO is supported through MSn, MI-variables: MI921, MI923, MI925, MI926, MI928 and MI929. There is a very good description in the Turbo PMAC User’s Manual starting on page 362 (specifically page 364 for MACRO). I don’t believe the F-MAC module supports position compare. It only supports position capture for homing.


A compiled PLC 0 looking at the position register will probably be your best altaernative.

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