Reference Guide

PMAC Quick Reference Guide
Motion Programs 59
• 100% Online or CMD command that restores the real-time reference (1 msec =
1 msec).
• M197 = I10 Suggested M-Variable for time base change. Equal to I10 is 100%, equal
to 0 is 0%.
The variable Ix94 controls the rate at which the time base changes:
23
2
2t
I10
Ix94
⋅
=
, where t is the slew rate
time in msec.
External Time Base Control (Electronic Cams)
The time reference of each coordinate system can be changed from the default internal reference,
controlled by the % command and variables Mx97, to an external source (usually a frequency reference
from a master encoder). A simple change of the variable Ix93 allows switching between the internal time
base and an external source. In this fashion, motion programs can be developed and tested running in
real-time (internal time base) and synchronized later to a master frequency when proven to be functional
and completed.
The only setup part of this feature is an entry in the conversion table that will also indicate a scale factor
for the maximum frequency that the master can possibly input to PMAC. This maximum frequency will
represent 100% or real time.
Position Following (Electronic Gearing)
PMAC has several methods of coordinating the axes under its control to axes not under its control. The
simplest method is basic position following. This is a motor-by-motor function, not a coordinate system
function as time-base following. An encoder signal from the master axis (which is not under PMAC’s
control) is fed into one of PMAC’s encoder inputs. Typically, this master signal is either from an open-
loop drive or a handwheel knob. Ix05 and Ix06 control this function.
Cutter Radius Compensation
PMAC provides the capability for performing cutter (tool) radius compensation on the moves it performs.
This compensation can be performed among the X, Y, and Z-axes, which should be physically
perpendicular to each other. The compensation offsets the described path of motion perpendicular to the
path by a programmed amount. Cutter radius compensation is valid only in LINEAR and CIRCLE move
modes. The moves must be specified by F (feedrate), not TM (move time). PMAC must be in move
segmentation mode (I13 > 0) to do this compensation. (I13 > 0 is required for CIRCLE mode anyway.)
Program commands CC0, CC1, CC2, CCR and NORMAL control this feature.