Delta ASDA-A3 Series, User Manual

Page: 204 / 845

ASDA-A3 Motion Control
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7
7.1.2 Monitoring variables of PR mode
The PR mode provides four monitoring variables for the servo command and feedback:
command position (PUU), PR command end register, feedback position (PUU), and position
error (PUU). These are described as follows:
1.
Command position (PUU): monitoring variable code 001. The target position of the motion
command generated per scan cycle during servo operation (updated every 1 ms),
simplified as Cmd_O (Command Operation).
2.
PR command end register: monitoring variable code 064. The target position of the PR
command, simplified as Cmd_E (Command End). When a command is triggered, the
servo drive calculates the target position and then updates to PR command end register.
3.
Feedback position (PUU): monitoring variable code 000. The encoder feedback position
(coordinates), simplified as Fb_PUU (Feedback PUU).
4.
Position error (PUU): monitoring variable code 002. The deviation between the command
position (PUU) and the feedback position (PUU), simplified as Err_PUU (Error PUU).
How these four monitoring variables work is shown in Figure 7.1.2.1. After the servo issues a
Position command, the servo sets the position of Cmd_E once the target position data is
acquired. The motor operates to the target position based on the PR path setting. Cmd_O
calculates the amount of command deviation in each fixed cycle and sends it to the servo drive,
where it is treated as a dynamic command. Fb_PUU is encoder feedback position and Err_PUU
is the deviation of Cmd_O minus Fb_PUU.
Err_PUU
Before
command
issued
Fb_PUU
Cmd_O
Cmd_E
Err_PUU
Fb_PUU
Cmd_O
Cmd_E
Err_PUU
Fb_PUU
Cmd_O
Cmd_E
Err_PUU
Fb_PUU
Cmd_O
Cmd_E
Err_PUU
Fb_PUU
Cmd_O
Cmd_E
Command in
execution
Command
completed
Motor
positioned
After
command
issued
Figure 7.1.2.1 Timing diagram for PR mode monitoring variables