4 Feed Axis Operation
4.6.1 Communications Cycle and Transmission Cycle Settings
4-24
4.6
Speed References When Performing Position Control from the
Host Controller
In systems that use MECHATROLINK-III, generally the SERVOPACK performs position control and speed
control. In some cases, however, the host controller performs position control while the SERVOPACK per-
forms only speed control. In this case, the host controller has a position control loop and sends speed refer-
ences (in pulses/s) to the SERVOPACK via MECHATROLINK-III communications.
4.6.1
Communications Cycle and Transmission Cycle Settings
In systems that use the host controller to perform position control and the SERVOPACK to perform speed
control, sending speed references to the SERVOPACK and receiving feedback data must be performed with a
faster cycle.
Therefore, we recommend a communications cycle of 1 ms or less and a transmission cycle of 250
μ
s.
Set the transmission cycle in the
t_mcyc
member of the JL100_USER_PAR structure in the MECHA-
TROLINK-III access driver. Set the communications cycle in the COM_TIM parameter to the CONNECT
command.
Terminology: Communications Cycle
This is the cycle for communications for sending the references that are created by the host controller.
Terminology: Transmission Cycle
This is the cycle for cyclic communications.
Example
Transmission cycle: 250
μ
s, Communications cycle: 250
μ
s
→
COM_TIM = 1
Transmission cycle: 250
μ
s, Communications cycle: 500
μ
s
→
COM_TIM = 2
Transmission cycle: 250
μ
s, Communications cycle: 1 ms
→
COM_TIM = 4
By setting the transmission cycle to the minimum time of 250
μ
s, you can minimize the delay required by the
host controller to retrieve the latest information from the SERVOPACK.
kp
Controller
Position Control
Position deviation
Follow-up
Follow-up for
SV-OFF or speed
reference
Infinite-length
processing
SERVOPACK
Speed
Control
Motor
Encoder