User's Manual

Turbo PMAC User Manual
288 Writing and Executing Motion Programs
All motors must come to a stop, either at the originally specified position, or at the post-trigger position,
before Turbo PMAC will calculate any further in the motion program. This means that there is no
blending of the post-trigger move into any subsequent moves.
The captured value of the sensor position at the trigger is stored in a dedicated register if later access is
needed. The units are in counts; for incremental encoders, they are relative to the power-up/reset
position.
Turbo PMAC sets the motor home-search-in-progress status bit (bit 10 of the first motor status word
returned on a ? command) true (1) at the beginning of a programmed move-until-trigger move. The bit is
set false (0) either when the trigger is found, or at the end of the move.
Turbo PMAC also sets the motor trigger move status bit (bit 7 of the second motor status word returned
on a ? command) true at the beginning of a programmed move-until-trigger move, and keeps it true at
least until the end of the move. If a trigger is found during the move, this bit is set false at the end of the
post-trigger move; however, if the pre-trigger move finishes without finding a trigger, the bit is left true at
the end of the move. Therefore, this bit can be used at the end of the move to tell whether the trigger was
found or not.
Altered-Destination Moves
Turbo PMAC gives you the capability for altering the destination of certain moves in the middle of the
execution of those moves by issuing an on-line command. This allows you to start a move with a
tentative destination and then change the destination during the move, with a smooth transition to the
altered destination. If no move is currently executing, this feature also gives the capability of
commanding a simple programmed move without using a program buffer.
This technique works with RAPID-mode moves only. The only motion mode whose destination can be
altered on the fly is RAPID mode, and the only motion mode that can be used to approach the new
destination is RAPID mode.
Altered-Destination Command
This feature is implemented by the on-line coordinate-system-specific command
!{axis}{constant}[{axis}{constant}…] or its variant
!{axis}Q{constant}[{axis}Q{constant}…] . The exclamation point identifies this
command as the on-line altered-destination command. The axis letters and their associated values specify
the new destination.
In the first case (e.g. !X3.0Y2.7), the constant value associated with each axis letter directly specifies
the new destination of the axis. Typically, this first case is used when the command is issued from a host
computer.
In the second case (e.g. !XQ21YQ22), the constant value associated with each axis letter after the ‘Q’
character specifies the number of the Q-variable for the coordinate system whose value represents the
new destination for the axis. For example, if Q21=3.0 and Q22=2.7, then !XQ21YQ22 is equivalent to
!X3.0Y2.7. Usually, this second case is used when the command is issued from a Turbo PMAC PLC
program.
The values specified in this command are always positions of the new destinations (relative to “program
zero”), not distances from previous commanded positions. That is, this command is always effectively in
absolute mode, regardless of whether the axes are in absolute or incremental mode. If the axes are in
incremental mode, they will stay in incremental mode for subsequent buffered program commands.
If there is no commanded move in progress when this command is issued, Turbo PMAC will execute a
RAPID-mode point-to-point move to the specified coordinates. This makes it equivalent to a jog-to-
position command in action, although the destination is specified in user units, not counts.