Siemens SIMATIC PCS 7 System Manual page 52

APF Engineering Tool
4.5 Data formats
Date format
In S7, only the years 1990 to 2089 are specified in the "DATE_AND_TIME" data type because
the year is represented by two digits only. All inputs and outputs of a block that are to represent
date/time are based on the S7 "DATE_AND_TIME" data type. It consists of two double words
that are used separately as two inputs/outputs in the blocks of the APF Toolbox; the same
name is assigned to both but the name of the second double word ends in "B" (e.g., DATE1
and DATE1B). To convert to the "DATE_AND_TIME" data type, the two double words can be
used together in direct sequence.
The two double words are structured as follows:
Double word
1
1
1
1
2
2
2
2
2
MSB = 4 most significant bits
LSB = 4 least significant bits
Refer to the PCS 7 Help on the "DATE_AND_TIME" data type for more detailed information.
52
Bytes
0 Year
1 Month
2 Day
3 Hour
4 Minute
5 Second
6 The two most significant digits for milliseconds
7 (4 MSB) The least significant digit for milliseconds
7 (4LSB) Day of the week (1=Sunday, 2 = Monday, etc.)
Explanation
Advanced Process Functions Engineering Manual
System Manual, 07/2016, A5E38719921-AA