Precautions For Use Of Control Syntaxes - Mitsubishi Electric MELSEC Q Series Programming Manual

4 ST PROGRAM EXPRESSIONS

4.3.5 Precautions for use of control syntaxes

IF X0 THEN
ST program
END_IF;
LD X0
List program
MOV K100 D0
[Remarks]
In only the conditional statement area, the processing time is shorter than when ST is not used.
However, since the comparison target of the IF conditional statement in ST is the Boolean expression,
complicated comparison can be made easily.
IF D0 = 0 THEN
ST program
END_IF;
LD = D0 K0
List program
MOV K100 D0
[Remarks]
In only the conditional statement area, the processing time is shorter than when ST is not used.
However, since the comparison target of the IF conditional statement in ST is the Boolean expression,
complicated comparison can be made easily.
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This section explains the number of used steps, operation processing time and
instructions for use of the control syntaxes in an ST program.
(1) Number of used steps and operation processing time for use of
control syntaxes
The number of used steps and operation processing time for use of the control
syntaxes will be explained.
The operation processing time is calculated by addition of the processing times of
the instructions. Use it as reference for program creation.
(a) IF conditional statements
IF conditional statement 1
D0 : = 100;
IF conditional statement 2
D0 : = 100;
Operation Processing
Number of Steps
Time (Q25H)
7
3
Operation Processing
Number of Steps
Time (Q25H)
9
5
Operation Processing
Time (Q00J)
1.534
0.134
Operation Processing
Time (Q00J)
1.6
0.20
Unit ( µ s)
10.9
0.90
Unit ( µ s)
11.5
1.50
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