ISPSoft User Manual

ISPSoft User Manual
11.2.2 Conditional Structure─IF
• Format
• Description
If the value of Boolean expression 1 is TRUE, Sub-statement 1 will be executed. If the value of
Boolean expression 1 is FALSE, Boolean expression 2 will be evaluated. If the values of all the
Boolean expressions are FALSE, Other sub-statement will be executed.
• Rules and limits
‣ A Boolean expression can be a device, a symbol, or an arithmetic expression. It can not be a
constant.
‣ A sub-statement can be a legal statement, or an IF statement.
‣ There is no limit on the number of sub-statements following THEN or ELSE.
‣ The ELSIF sections and the ELSE section can be omitted. If the ELSE section is omitted, and
the values of all the Boolean expressions are FALSE, no sub-statement will be executed.
‣ Users can add ELSIF sections to a conditional structure at will. There is only one ELSE section
in a conditional structure. The ELSE section in a conditional structure is at the last section of
the conditional structure.
• Example
Example 1: If M0 is ON, M1 will be set to ON, and M2 will be set to OFF. If M0 is not ON, the step
will end. No matter what the value of M0 is, the value of M0 will be assigned to M0.
Example 2: If the value of DT is larger than 5, OUT_0 will be set to ON, and OUT_1 will be reset
to OFF. If the value of DT is not larger than 5, the value of OUT_2 will be assigned to
OUT_0 and OUT_1.
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