User Manual Chapter 9
GFK-1742F Jan 2020
Combined Follower and Commanded Motion 240
9.2 Follower Motion Combined with Motion
Programs
Motion commands from stored programs or the Move %AQ command can also be
combined with the master command to drive the follower axis. These point-to-point move
commands can come from one of the stored motion programs 1 through 10 and any stored
subroutines they may call. The Move %AQ command is treated as a single line motion
program, which uses the present Jog Velocity and Jog Acceleration. Program execution is
started by the host controller setting an Execute Program n %Q bit or sending a Move %AQ
command.
If there is no master command, the axis can be commanded solely from the stored motion
program data. Thus, with no master input to Servo Axis 2 and Commanded Position 2
selected as the master source for Servo Axis 1, a stored program can be used to control
Servo Axis 2 with Servo Axis 1 following per the designated ratio.
When PMOVEs are executed with Follower not enabled, the In Zone %I bit must be set at the
end of the move before programmed motion will continue. When Follower is enabled, since
In Zone may not turn on while also following a master command, the In Zone indication will
not be required to continue. The next Move will take place when the commanded distance
for the previous move has completed. The In Zone %I bit will always indicate the true in zone
condition.
The active commanded position updated and used by the stored motion program is
referred to as Program Command Position. Each time a program is selected for execution,
this position register is initialized in one of the two ways listed below.
1.
If the follower is not enabled, the Program Command Position is set to the current
Commanded Position = Actual Position + Position Error.
2.
If the follower is enabled, the Program Command Position is set to the Program
Reference Position (0). Since the Program Command Position is only updated by
internally generated commands (and not by the master command), it will then
indicate the position commanded by the stored program. Absolute move
commands from the stored program will be referenced to the Program Reference
Position.
Therefore when an absolute move is the first move in a program, it will behave like
an incremental move when the follower is enabled. Additional absolute moves
within a program will be referenced to the current Program Command Position,
which is updated by each move. Once a motion program finishes, executing another
program with follower enabled will again cause the Program Command Position to
be initialized to zero.
Position ranges (in counts) for the Actual and Program Command Position registers are
indicated in the figure below.
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