Galil Motion Control DMC-18 2 Series User Manual page 94

Example - Electronic Gearing
Objective: Run two geared motors at speeds of 1.132 and -0.045 times the speed of an external master.
The master is driven at speeds between 0 and 1800 RPM (2000 counts/rev encoder).
Solution: Use a DMC-1832 controller, where the Z-axis is the master and X and Y are the geared
axes.
MO Z
GA Z, Z
GR 1.132,-.045
Now suppose the gear ratio of the X-axis is to change on-the-fly to 2. This can be achieved by
commanding:
GR 2
Example - Gantry Mode
In applications where both the master and the follower are controlled by the DMC-18x2 controller, it
may be desired to synchronize the follower with the commanded position of the master, rather than the
actual position. This eliminates the possibility of an oscillation on the master passing the oscillation on
to the slave.
For example, assume that a gantry is driven by two axes, X and Y, one on each side. This requires the
gantry mode for strong coupling between the motors. The X-axis is the master and the Y-axis is the
follower. To synchronize Y with the commanded position of X, use the instructions:
GA, CX
GR,1
GM,1
PR 3000
BG X
You may also perform profiled position corrections in the electronic gearing mode. Suppose, for
example, that you need to advance the slave 10 counts. Simply command
IP ,10
Under these conditions, this IP command is equivalent to:
PR,10
BGY
Often the correction is quite large. Such requirements are common when synchronizing cutting knives
or conveyor belts.
Example - Synchronize two conveyor belts with trapezoidal velocity correction.
GA,X
GR,2
PR,300
SP,5000
AC,100000
DC,100000
BGY
DMC-18x2
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Turn Z off, for external master
Specify Z as the master axis for both X and Y.
Specify gear ratios
Specify gear ratio for X axis to be 2
Specify the commanded position of X as master for Y.
Set gear ratio for Y as 1:1
Set gantry mode
Command X motion
Start motion on X axis
Specify an incremental position movement of 10 on the Y axis.
Specify position relative movement of 10 on the Y axis
Begin motion on the Y axis
Define X as the master axis for Y.
Set gear ratio 2:1 for Y
Specify correction distance
Specify correction speed
Specify correction acceleration
Specify correction deceleration
Start correction
Chapter 6 Programming Motion • 83