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MELSEC-Q
4 SEQUENCE PROGRAM CONFIGURATION AND EXECUTION
CONDITIONS
(e) Execution during END processing:
When the execution condition of fixed scan execution type programs are
established during the wait time of END instruction while the constant scan
is executed, the fixed scan execution type programs are executed.
(f) Perform the processing of the index register when the program is switched
from the scan execution type program to the fixed scan execution type
program by seeing Section 10.6.2.
(3) Setting of fixed scan execution type program for high speed
execution and overhead time
When fixed scan execution type programs are executed, the processing below is
performed.
• Save and return of index resister
• Save and return of file name of file resister in use
If "High Speed Execution" is selected from the interrupt program/fixed scan
execution type program at the "PLC system" tab screen in the “(PLC) Parameter"
dialog box, the processing above will not be performed.
As a result, the overhead time for the fixed scan execution type programs can be
reduced.
(Overhead time
s)
CPU type
High speed execution is not
selected
High speed execution is
selected
Q02CPU
380
230
Q02HCPU, Q06HCPU, Q12HCPU, Q25HCPU
165
100
(4) Cautions on programming
(a) If a device is turned ON in a fixed scan execution type program by a PLS
instruction, it is kept ON until the same type of the fixed scan execution type
program is executed again.
X0
OFF
ON
M0
OFF
ON
END 0
0 ENDEND0
END 0 0 END END 0
PLS M0
X0
PLS M0
X0
Switched OFF by PLS M0 instruction
Switched ON by PLS M0 instruction at X0 leading edge (OFF to ON)
Fixed scan execution
type program execution
(b) During the execution of a fixed scan execution type program, interruption is
prohibited (DI). Therefore, do not execute EI/DI instructions during the
programming of the fixed scan execution type program.
(c) During the programming of a fixed scan execution type program, a timer
cannot be used.
Because the timer updates the current values and turns ON/OFF at the
time of execution of OUT T
instruction, if the timer is used during the
programming in the fixed scan execution type program, the current values
will be updated only when the fixed scan execution type program is
executed, and normal measurement will be disabled.
(d) When a fixed scan execution type program is executed, an interruption must
be allowed by an EI instruction in the initial execution type program/scan
execution type program.
Содержание QCPU (Q Mode)
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