Siemens S5-100U - Number Representation

S5-100U Introduction to STEP 5
You can use the COMPRESS programmer function to clean up internal program memory.
If there is a power failure during the compress operation when a block is being shifted and block
shifting can not be completed, the CPU remains in the STOP mode. The “NINEU” error message
appears. Both the“BSTSCH” and the “SCHTAE” bits are set in the ISTACK.
Remedy: Overall reset.
7.6 Number Representation
With STEP 5 you can work with numbers in the following five representations:
• Decimal numbers from -32768 to +32767 (KF)
• Hexadecimal numbers from 0000 to FFFF (KH)
• BCD-coded numbers (4 tetrads) from 0000 to 9999
• Bit patterns (KM)
• Constant byte (two-byte representation) from 0 to 255 for each byte (KY)
Number Formats
The programmable controller is designed to process binary signal states (only “0” and “1”).
Therefore the programmable controller represents all numbers internally as 16-bit binary numbers or
as bit patterns.
Four bits can be combined into a tetrad (BCD) to shorten the binary code representation. The value
of these tetrads can be displayed in hexadecimal representation.
Example: 16-bit binary coded number and shortened hexadecimal representation
Figure 7-16. Bit Assignment of a 16-Bit Fixed-Point Binary Number
Binary code representation
Word no.
Byte no.
Bit no.
Meaning
n
15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
n+ 1 (low byte)n (high byte)
2
15
2
14
2
13
2
12
2
11
2
10
2
9
2
8
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
0 0 0 1 1 1 1 0 1 1 0 0 0 1 11
Hexadecimal representation
a a a a a
a
a a a
a
a
a a a
a
a a a a a
1
a a a a a
a
a a a
a
a
a a a
a
a a a a a
F
a a a a a
a
a a a
a
a
a a a
a
a a a a a
6
a a a a a
a
a a a
a
a
a a a
a
a a a a a
3
EWA 4NEB 812 6120-02 7-31