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4 SEQUENCE PROGRAM CONFIGURATION AND EXECUTION
CONDITIONS
4.2.5 Fixed scan execution type program
Fixed scan
execution type
program execution
Fig. 4.5 Execution of Fixed Scan Execution Type Programs during Network Refreshing
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(1) Definition of fixed scan execution type program
(a)
This program is executed at specified intervals.
Without describing an interrupt point and IRET instruction, a fixed scan
execution can be performed for each file.
(b)
The type of execution is set to "Fixed Scan" at the "Program" tab screen in
the (PLC) parameter dialog box.
(2) Execution of fixed scan execution type program
(a)
Fixed scan execution type programs are executed at specified cyclic time
intervals.
When multiple fixed scan execution type programs have reached there
simultaneously, they are executed in the ascending order set at the
"Program" tab screen in the "(PLC) Parameter" dialog box.
(b)
Set the periodic interval at the "Program" setting tab screen in "(PLC)
Parameter" dialog box. The setting range varies with the set unit.
• When the unit is "ms": 0.5 to 999.5ms
• When the unit is "s": 1 to 60s
(c) When the specified times of fixed scan execution type programs and
interrupt programs (I28 to I31) have come simultaneously, the priority of
execution is given to the interrupt programs.
(d)
Execution during network refreshing
When the execution conditions of fixed scan execution type programs are
established during the network refreshing, the network refresh is
suspended, and interrupt programs are executed.
Therefore, even if the "block assurance of cyclic data for each station" is
made in the MELSECNET/H network system, the above operation will not
be assured when a device set to be refreshed is used in the interrupt
programs.
1
Interrupt factor
Link refresh
execution
REMARK
1: Refer to the following manual on the block assurace of cyclic data for each
station.
• Q-Corresponding MELSECNET/H Network System Reference Manual
10ms
10ms
MELSEC-Q
10ms
10ms
Link refresh operation is suspended,
and the interrupt program is executed.
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