User`s manual

Follower Motion
GFK-1742A Chapter 8 Follower Motion 8-3
8
Internal Master Axis Command generators
Commanded Position
for Axis 1 - Axis 4 represent internal master axis sources. The DSM314
follower loop will allow a slave axis to follow a selected internal command source as shown in this
example:
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 8-2.
Following Servo Axis 2 Encoder
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” value 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.
t
v
t
v
a45330
A
xis 1 (Follower)
A
xis 2 (Master)
A
:B
R
atio
=
1:2