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« on: February 14, 2013, 12:44:11 PM »
Hi Yanxin,
DotG has been designed for reproducing a one bit, ‘dot-dithered’ image (one with a varying density of equal sized dots to create the illusion of shade) and when set in ‘dot’ mode the laser is only fired when the X and Y axes are stationary.
To fire the laser I am using the M11P1/M10P1 command set together with an imaginary B axis and my Post Processor (see posting #641) essentially creates this code for each dot in the image:-
B0
M11P1 B1
M10P1 B0
B0 is at the start of the code and makes sure the imaginary B axis is in position 0.
M11P1 turns on Output #1 (as soon as the B axis starts to move). Output #1 is mapped to an LPT (parallel port) output pin which is in turn connected to my laser TTL(L) trigger.
Because the imaginary B axis takes time to move from position 0 to position 1, I have adjusted (by trial and error) the steps per unit, Velocity and Acceleration of this axis to produce the required time delay (laser on time).
M10P1 turns off Output #1 and thus the laser trigger as soon as the B axis starts to move back to position 0.
I hope this answers your questions.
Tweakie.