PPR(OPCSDEFS) Optical Printer Control System PPR(OPCSDEFS) NAME ppr - configure the 'pulses per revolution' for a motor SYNOPSIS ppr [chan] [pulses] EXAMPLE ppr a 2000 # microstepper system ppr a 4000 # microstepper with vistavision ppr a 400 # half stepper system DESCRIPTION Sets the number of pulses needed to rotate a motor one revolution. This command exists especially for the CAMERA and PROJECTOR motors. Keep in mind the OPCS hardware runs stepper motors at more than the motor's rated resolution. Microstepper systems can have as many as 2000 pulses per rev, and half stepper systems can have 400 per rev. The software uses the PPR value in two ways. One is to obviously translate frames into physical steps for the motors. The other is for the ALLSTOP routine (in the assembly run_hardware() subroutine) to know when to look for the ALLSTOP key, so it doesnt stop a motor in mid-revolution. NOTES PPR settings for the fader are never used by the software, since revolutions have no meaning in the context of running the shutter. PPR values should be divisible by two, esp. for the projector so that half phase shifts calculate to non-fractional steps. BUGS You cannot specify floating point values for PPR. This is not actually a bug..if your hardware is geared in such a way that a full revolution occurs in a fractional number of steps, you should probably fire the guy who built it and have the hardware rebuilt anyway. To avoid a nasty bug with the ALLSTOP key, and to have counters update properly, configure the PPR(OPCSDEFS) command for the D thru L channels to be '10' in your OPCSDEFS.OPC file, regardless of the actual number of pulses per revolution. This also ensures that slewing in JOG doesnt go in very large increments. ppr d 10 # non-shutter channels only ppr e 10 ppr f 10 ppr g 10 ppr h 10 ORIGIN Gregory Ercolano, Los Feliz California 11/29/89