SPD(OPCSDEFS) Optical Printer Control System SPD(OPCSDEFS) NAME spd - configure the default and fastwind/slewing speeds for a motor SYNOPSIS spd [chan] [normal] [fast] [scale] [offset] NOTE: any of the arguments [normal] [fast] [scale] [offset] can be a dash (-), indicating that argument won't be modified. EXAMPLES spd c .25 .1 1.0 0.0 # sets default speed for the camera motor: # .25 is normal running speed, # .10 is the slew speed (used by SEEK) # 1.0 and 0.0 indicate speeds are specified # as ROTATIONAL speeds. spd c .25 .1 3.0 0.0 # Same as above, but shows correct [scale] # value so EXPOSURES can be specified # for a 120 deg. shutter (3.0 = 360/120). spd c .25 .1 2.1176 # Same as above, but shows correct [scale] # value so EXPOSURES can be specified # for a 170 deg. shutter (2.1176 = 360/170) DESCRIPTION Normally, one of these commands for EACH motor should appear in the OPCSDEFS.OPC file. This command sets the initial running speeds for a motor, as well as how speeds are specified (ie. rotational or exposure speeds. See below.) This command also allows SCALEs and OFFSETs to be applied to speed values automatically to let you specify EXPOSURE speeds instead of rotational speeds... ROTATIONAL SPEED An example of a rotational speed could be .25, which would mean: a full rotation of the camera shaft will occur in .25 of a second, or 1/4 a second. This is how motor speeds are normally handled by the software. EXPOSURE SPEED An example of an exposure speed of .5 would mean the film exposes to light for 1/2 second. Since most shutters are 170 degrees (ie. exposing light for 170 degrees out of the total 360 degrees of rotation), the [scale] value can be used to compensate. You will want to decrease the camera's rotational speed. To do this, multiply 360/170 times the current speed to compensate for the fact that the shutter is only open for a fraction of a rotation. This is where the [scale] argument comes in. By setting [scale] to 2.1176 (360/170), you can then specify speeds as 'exposure speeds', and the system will compensate automatically. If you have a 120 degree shutter, use 3.0 (360/120) for the [scale] value. You need only do this for the camera motor..the projectors do not have to be set up this way, since the projectors always slave to the camera's speed whenever a tandem run is executed. EQUATION The following equation shows how scales and offsets are first applied to motor speeds: actual motor speed = (norm_speed * scale) + offset * spdinterp A value of 1.0 for [scale], and 0.0 for [offset] makes NO CHANGE in the norm_speed (normal running speed), and thus will reflect shaft rotation speed. 'spdinterp' will affect the equation only if a SPDINTERP(OPCSDEFS) command is configured, in which case the speed will be modified according to the current position of the SPDINTERP's master channel. SEE ALSO MRP(OPCSDEFS) - set 'maximum ramping pulses' for shutter runs RAMP(OPCSDEFS) - set maximum acclerations and velocities SPD(OPCS) - set the camera's exposure speed SPD(OPCSDEFS) - set a motor's running speeds RAMPCURVE(OPCSDEFS) - set ramping curves for shutter runs SPDINTERP(OPCSDEFS) - set auto-interpolation for exposure speeds BUGS Speeds of 0.0 will cause the software to blow out unpleasently. Avoid setting a motor's speed to zero, or doing any operation that would result in an actual speed of zero. ORIGIN Gregory Ercolano, Los Feliz California 11/29/89