Reference Manual

Turbo PMAC/PMAC2 Software Reference
Turbo PMAC Global I-Variables 181
 Isx20 = [4/3] * [400 cts/msec / (2 * 1.0 cts/msec
2
*5 msec/seg)] = 54 segments
Isx21 Coordinate System x Lookahead State Control
Range: 0 – 15
Units: none
Default: 0
Isx21 permits direct control of the state of lookahead execution, without going through Turbo PMAC’s
background command interpreter. This is useful for applications such as wire EDM, which can require
very quick stops and reversals.
 Setting Isx21 to 4 is the equivalent of issuing the \ quick-stop command.
 Setting Isx21 to 6 is the equivalent of resuming forward motion with the > resume forward command.
 Setting Isx21 to 7 is the equivalent of issuing the < back-up command.
 Setting Isx21 to 14 requests execution of a single segment in the forward direction.
 Setting Isx21 to 15 requests execution of a single segment in the reverse direction.
If monitoring Isx21 at other times, notice that the 4’s bit is cleared after the command has been processed.
Therefore, the following values will show:
 Isx21 = 0 when stopped with a quick-stop command.
 Isx21 = 2 when running forward in lookahead.
 Isx21 = 3 when running reversed in lookahead.
 Isx21 = 10 when has executed a single forward segment in lookahead.
 Isx21 = 11 when has executed a single reverse segment in lookahead.
Note:
The use of DWELL, WHILE({condition})WAIT, and a violation of the double-
jump-back rule momentarily switches PMAC out of lookahead mode. Therefore,
these constructs should not be used in programs and sub-programs when Isx21 will
be used to control their lookahead state.
Note:
In preliminary versions of the Turbo PMAC firmware, Isx21 served a different
function. That variable value is now a constant value (3) set by the firmware.
Isx50 Coordinate System x Kinematic Calculations Enable
Range: 0 – 1
Units: none
Default: 0
Isx50 controls whether the special forward-kinematic and inverse-kinematic program buffers for
Coordinate System x are used to relate the motor and axis positions for the coordinate system.
If Isx50 is set to 0 (the default), Turbo PMAC will use the relationships set up in the axis-definition
statements for the coordinate system to compute the relationship between motor positions and axis
positions. The inverse of the axis-definition equations is used to compute the starting axis positions on an
R (run), S (step), or PMATCH command. The axis-definition equations are used to convert programmed
axis positions to motor positions each programmed move or move segment. Even if the forward-
kinematic and inverse-kinematic programs have been loaded for the coordinate system, they will not be
used.
If Isx50 is set to 1, Turbo PMAC will use the relationships set up in the special kinematic program buffers
to compute the relationship between motor positions and axis positions. The forward-kinematic program