3
SEQUENCE PROGRAM CONFIGURATION AND
EXECUTION CONDITIONS
3.3 Settings for Creation and Execution of Multiple Sequence Programs
3.3.5 Fixed scan execution type program
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(3) Precautions for programming
(a) Device turned ON/OFF by PLS or similar instruction
When using an instruction such as PLS, by which an execution condition turns ON
from OFF in the next step and it turns the operation device ON, the device
remains ON until the same instruction is executed.
When using an instruction such as PLF, by which an execution condition turns
OFF from ON in the next step and it turns the operation device ON, the device
remains ON until the same instruction is executed.
(b) EI/DI instruction
During execution of a fixed scan execution type program, interrupts are disabled
(DI) so that any other interrupt is not enabled.
Do not execute the EI/DI instruction during a fixed scan execution type program
execution.
(c) Timer (T) and counter(C)
Timer (T) and counter (C) cannot be used in fixed scan execution type programs.
Timer (T) cannot perform measurement normally when executing fixed scan
execution type program multiple times during one scan.
Counter (C) in a fixed scan execution type program cannot perform measurement
normally when executing fixed scan execution type program multiple times during
one scan or due to the OUT C instruction status at execution.
(d) Instructions not available in fixed scan execution type programs
For instruction not available in fixed scan exection type programs, refer to each
instruction of programming manual.
Figure 3.48 Device turned ON by PLS instruction in fixed scan execution type program
X0
OFF
ON
M0
OFF
ON
END 0
0 END END 0
END 0 0
END END 0
X0
X0
Fixed scan execution
type program
Turned ON when PLS M0 instruction is executed on
leading edge (OFF ON) of X0.
Turned OFF when PLS M0
instruction is executed.
PLS M0
PLS M0