Introduction
The data types in BCD format belong to the EDT (Elementary data type) family, which includes single rather than derived data types (tables, structures, function blocks).
Reminder Concerning BCD Format
The Binary Coded Decimal (BCD) format is used to represent decimal numbers between 0 and 9 using a group of four bits (half-byte).
In this format, the four bits used to code the decimal numbers have a range of unused combinations.
Correspondence table:
Decimal |
Binary |
|---|---|
0 |
0000 |
1 |
0001 |
2 |
0010 |
3 |
0011 |
4 |
0100 |
5 |
0101 |
6 |
0110 |
7 |
0111 |
8 |
1000 |
9 |
1001 |
1010 (unused) |
|
1011 (unused) |
|
1100 (unused) |
|
1101 (unused) |
|
1110 (unused) |
|
1111 (unused) |
Example of coding using a 16 bit format:
Decimal value 2450 |
2 |
4 |
5 |
0 |
Binary value |
0010 |
0100 |
0101 |
0000 |
Example of coding using a 32 bit format:
Decimal value 78993016 |
7 |
8 |
9 |
9 |
3 |
0 |
1 |
6 |
Binary value |
0111 |
1000 |
1001 |
1001 |
0011 |
0000 |
0001 |
0110 |
Data Types in BCD Format
Three data types:
Type |
Designation |
Scale (bits) |
Default value |
|---|---|---|---|
DATE |
Date |
32 |
D#1990-01-01 |
TIME_OF_DAY |
Time of day |
32 |
TOD#00:00:00 |
DATE_AND_TIME |
Date and Time |
64 |
DT#1990-01-01-00:00:00 |