Groups 06/2005 Danaher Motion
132 Rev E M-SS-005-03l
6.10.1. Settling Time
The MC actively watches to determine if the groups are settled into position.
In most applications, the group position feedback is slightly delayed from the
position command. After a move is complete, some time is required for the
actual position to settle out to the commanded position. This time is called
settling time.
Ideally, settling time allows the group to move so that position error is zero .
However, in real systems you must allow for the condition where the position
error never quite reaches zero. On the MC, you specify how low you
consider to be low enough with POSITIONERRORSETTLE or PESETTLE:
xyTableGroup.PESettle = 0.01
After the motion generator completes a move that ends with zero speed, it
actively monitors the position error of the group (the orthogonal combination
of the position error of each axis) to determine when it is between
±PESETTLE. If it is within this range, <group>.ISSETTLED is true (1).
Otherwise, it is false.
In some applications, you must ensure that the position error remains below
PESETTLE for a specified period of time before the group is considered
settled. The MC allows you to specify this time period with the
<group>.TIMESETTLE or <group>.TSETTLE (given in milliseconds). If the
position error exceeds PESETTLE during this time, the timer is reset. If
position error is within PESETTLE’s range for the time specified by
TSETTLE, <group>.ISSETTLED is true (1). Otherwise, it is false. For
example:
PESettle = 0.01
TimeSettle = 0.01 xyTableGroup.StartType = INPOSMove
xyTableGroup {100 , 200}
Move xyTableGroup {200 , 400}
This example requires that after the motion generator completes the first
move and xyTableGroup has position error at or below 0.01 for at least 10
ms before the group is settled. Since STARTTYPE is INPOS, the motion
generator waits for these conditions before starting the second move.
6.10.2. Start Moves
When the motion buffer is empty, group moves begin immediately. If you
need to delay the next motion, you have two options. You can either use
DELAY to insert a fixed delay time or STARTTYPE to delay, depending on a
condition.
Use DELAY to force the motion generator to wait a fixed period of time
between moves. The motion element xyTableGroup must be specified in
DELAY. For example:
Move xyTableGroup {100, -100}
Delay xyTableGroup 1000
Move xyTableGroup {200, 500}
forces a 1 second delay between the two moves. DELAY has units of
milliseconds and must be greater than zero.
DELAY differs from SLEEP in that SLEEP delays program execution and
DELAY delays only the motion generator. DELAY is forced to the
STARTTYPE mode.
