Date and time instructions
300
Part II IEC Instructions
SUB_DATE_DATE
Subtracts a date from another date
To add an enable input and enable output to the instruction, select [With EN/ENO] from the
"Instructions" pane (LD, FBD or IL editor). To reuse an instruction select "Recently used" from the
context menu or press <Ctrl>+<Shift>+<v> in the programming window.
PLC types
Availability of SUB_DATE_DATE (see page 1331)
The TIME result is only valid if the difference between the minuend and
subtrahend is smaller than or equal to the maximum TIME duration allowed.
Otherwise an overflow of the TIME result variable occurs and the CARRY flag is
set.
Data type I/O Function
DATE 1st input minuend
DATE 2nd input subtrahend
TIME output result
TIME_result := SUB_DATE_DATE(DATE_value1, DATE_value2);
Description
SUB_DATE_DATE subtracts a value of the data type DATE from another DATE value. The result
is stored in the output variable of the data type TIME.
Data types
Example
In this example the function has been programmed in ladder diagram (LD) and structured text (ST).
POU header
All input and output variables used for programming this function have been declared in the POU
header.
LD
ST
When programming with structured text, enter the following: