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User Manual
Chapter 8
GFK-1742F
Jan 2020
Follower Motion
225
8.3.1
Example 2: Following an Internal Master command
In this example, Axis 1 of the DSM314 is configured with Follower Master Source 2 =
Commanded Position 2 and the Select Internal Master %Q bit is ON. The A:B ratio is 1:2.
Axis 2 is commanded to Move at Velocity 12000 and then 0. Axis 1 follows axis 2 at half of
the axis 2 velocity and acceleration and moves only half the distance that axis 2 has moved.
Figure 96: Following Servo Axis 2 Encoder
8.4
A:B Ratio
A DSM314 axis following a master input can do so at a wide range of slave : master (A:B)
ratios. The “A” value can be any number from –32768 to 32767. The “B” va
lue can be
anywhere between 1 and 32767. The magnitude of the A:B ratio can be from 1:10,000 to
32:1. Thus very precise ratios such as 12,356:12,354 or 32,000:1024 can be used.
The Follower A/B Ratio %AQ command can be used to change the A:B ratio at any time,
even while following. However, an invalid ratio will generate a status error and be ignored.
An invalid ratio is a ratio with B equal to or less than zero or A:B magnitude greater than
32:1 or less than 1:10,000.
When following with a non 1:1 ratio, the velocity profile of the master and follower will
look somewhat different. Horizontal lines, indicating constant velocity, and slanted lines,
indicating acceleration and deceleration, will be different. If the A:B ratio is less than 1:1,
the follower velocity and acceleration will be less than the master. Likewise, if the A:B ratio
is greater than 1:1, the follower velocity and acceleration will be greater than the master.
The duration of motion, and time that the slave axis will accelerate, decelerate, or stay at
constant velocity are the same for the master and follower.
The distance moved, which in a velocity profile is the area between the graph and the time
axis, will be that of the master multiplied by the A:B ratio. If A is zero, no following motion
will be generated. If A is negative, the following axis will move with the direction of motion
reversed.