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MELSEC-Q
4 SEQUENCE PROGRAM CONFIGURATION AND EXECUTION
CONDITIONS
4.2.3 Low speed execution type program
(1) Definition of low speed execution type program
(a) Low speed execution type programs are executed only during "constant
scanning surplus time" or during the period designated for "low speed
program execution time".
1) For a constant scan time with enhanced control accuracy, designate a
constant scan time setting at the "PLC RAS" tab screen in the “(PLC)
Parameter".
(Setting range: 0.5 to 2000 ms, setting unit: 0.5 ms)
2) To secure execution time for low speed execution type programs at
each scan, designate a low speed program execution time in the "PLC
RAS" tab screen the (PLC) "Parameter".
(Setting range: 1 to 2000 ms, setting unit: 1 ms)
3) In order to execute a low speed execution type program, set either the
constant scan time or low speed program execution time.
(b) Set the execute type of the low speed program to "low speed" in the
program of the PLC parameters.
(c) The low speed execution type program is used for programs which do not
require execution in each scan, for example programs for printer output.
(2) Executing multiple low speed execution type programs
When multiple low speed execution type programs are used, they are executed
one by one in ascending number order of the program in the PLC parameters.
(3) Execution time of the Low speed execution type program to be
executed per scan
(a) If all the low speed execution type program operation is completed within
one scan and there is surplus time, the processing executed after that
depends on the ON/OFF status of special register SM330 and the
execution condition for low speed execution type programs.
1) Asynchronous method (SM330 = OFF)
Method in which low speed execution type program operation is
continued in the surplus time.
2) Synchronous method (SM330 = ON)
Method in which even if there is surplus time, low speed execution
type program operation is not continued, and operation starts again
from the next scan.
Execution condition for low speed execution type programs
Operation method for low
speed execution type
programs
SM330
setting
status
When constant scan time
is set
When low speed program
execution time is set
Asynchronous method
OFF
The low speed execution
type program is re-
executed
1
.
The low speed execution type
program is re-executed
2
.
Synchronous method
ON
Constant scan waiting
time is generated
3
.
Scan execution type program
operation is started
4
.
Содержание QCPU (Q Mode)
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