466
28 FUNCTIONS
28.3 Tracking Transfer
■Asynchronous tracking mode
In the asynchronous tracking mode, the control system starts the next scan without waiting for notifications of data reception/
reflection completion from the standby system.
Unlike the synchronous tracking mode, the scan time is not affected by waiting time for data reception/reflection completion.
When the standby system does not receive the tracking data from the control system, the standby system starts the next
scan.
When the control system CPU module is in the RUN state and the standby system CPU module is in the STOP state
*1 When the constant scan is used, waiting time for the constant scan is generated.
In the control system, the scan time is extended by the following tracking send processing time.
In the standby system, the scan time increases by the following tracking receive processing time.
■When the mode is switched from the asynchronous tracking mode to the synchronous
tracking mode
When the mode is switched from the asynchronous tracking mode to the synchronous tracking mode, the standby system
receives the tracking data twice in one scan. Therefore, the scan time of the standby system is extended by the following time.
Scan time of the standby system: Standby system scan time 2 + Control system scan time
Item Description
(1) Tracking send
processing
(2) Waiting for completion of tracking
data reflection
After receiving a notification of the reflection completion from the standby system, the
control system sends the tracking data.
When a notification of reflection completion is not arrived (4), the control system does
not send tracking data in the scan.
(3) Sending tracking data The control system sends the tracking data. After completing the send, the control
system starts another END processing without waiting for a notification of receive
completion from the standby system.
Item Description
(5) Tracking receive
processing
(6) Waiting for tracking data reception The standby system receives the tracking data from the control system. When the
standby system does not receive the tracking data, the standby system starts the next
scan.
After receiving the tracking data, the standby system notifies the control system of the
receive completion and reflects the tracking data.
(7) Reflecting tracking data The standby system reflects the tracking data. After the reflection completion, the
standby system notifies the control system of the reflection completion and starts the
next scan.
(1)
END
(6) (6) (6) (6) (6) (6) (6) (6)
(5)
(7)
MAIN MAIN MAIN
(2)
(3)
END
(2) (2)
(1)
(3)
ENDEND
END END END END END END END
(4)
END
*1
*1
*1
Scan time of the control system CPU module
Tracking data
Control system
CPU module
Standby system
CPU module
Scan time of the standby system CPU module
I/O refresh
(input only)
I/O refresh
Tracking data
Data
received
Data
reflected
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