Omron GRT1-ML2 Hardware Reference Manual page 43

System philosophy
Absolute SSI encoder ATYPE=48
With SERVO = ON, this is an axis with analogue speed reference output and
absolute SSI encoder feedback. The position loop is closed in the TJ1-MC__
and the resulting speed reference is sent to the axis.
With SERVO = OFF, the position of the external absolute SSI encoder is
read. The analogue output can be set with BASIC commands only and can
be used for general purposes.
See fig. 35 for reference.
Inverter axis ATYPE=49
This type allows Inverters (with built-in encoder interface) to be controlled on
the MECHATROLINK-II bus as servo axes.
From the controller point of view, Inverter axes are handled the same as
servo axes in MECHATROLINK-II Speed Mode (ATYPE=44).
Unlike the other axis types, this Inverter axis must be defined
programmatically with function 8 of the command INVERTER_COMMAND.
The Speed command to the Inverter and the feedback from the encoder is
refreshed in the Inverter every 5 ms. This is a DPRAM limitation. This means
that the use of the Inverter is similar to the use of a Servo Driver, but the
performance is lower.
Summary of axis types and control modes
The following table lists the axis types and their recommended modes for
speed control, position control and torque control.
/i
ATYPE SERVO Mode
40 OFF Position
(MECHATROLINK-II)
40 ON Position
(MECHATROLINK-II)
41 OFF Speed
(MECHATROLINK-II)
HARDWARE REFERENCE MANUAL
Comment
The position loop is closed in the Servo Driver.
No new motion command is allowed.
Recommended mode for position control with
MECHATROLINK-II axes.
Recommended mode for speed control with
MECHATROLINK-II axes. Set the speed with
S_REF.
fig. 38
TJ1-MC__
Position loop
SERVO = OFF
+
Profile generator _
Demanded Following Speed
position error command
Measured
position
TJ1-ML__ INVERTER
SERVO = OFF
ML-II
Speed Loop
Speed
command
DPRAM
REFRESH
EVERY 5ms
E M
38