Siemens SINUMERIK 808D Commissioning Manual page 107

Note
The permitted offset for an address is dependent on the access:
• Bit or byte access: any offset.
Byte-size variables are placed one next to another seamlessly in a DB.
• Word access: the offset must be divisible by 2.
Word-size variables (2 bytes) are always saved on straight offsets.
• Double word access: the offset must be divisible by 4.
Double word-size variables (4 bytes) are always saved on offsets that are divisible by 4.
Table A- 4
SM 0.0
SM 0.1
SM 0.2
SM 0.3
SM 0.4
SM 0.5
SM 0.6
Special bit memory SM bit definition (read-only)
Table A- 5
[r]
[r/w]
Table A- 6
1
8
16
32
Note
All the empty fields in the user interface are "reserved for Siemens" and may neither be
written to nor evaluated.
Fields designated with "0" always have the value "logical 0".
If there is no data format information, you can read or write to all the specified data formats.
Commissioning Manual
Commissioning Manual, 01/2015, 6FC5397-4EP10-0BA0
Special Marker SM Bit Definition
SM bits
Bit memory with defined ONE signal
Initial setting: first PLC cycle '1', subsequent cycles '0'
buffered data lost - only valid in first PLC cycle
('0' data ok, '1' data lost)
POWER ON: first PLC cycle '1', subsequent cycles '0'
60 s clock (alternating '0' for 30 s, then '1' for 30 s)
1 s clock (alternating '0' for 0.5 s, then '1' for 0.5 s)
PLC cycle clock (alternating one cycle '0', then one cycle'1')
Variable access rights
You can "read only" designated area
You can "read and write" designated area
Data format information
BIT
BYTE
INT/WORD
DINT/DWORD/REAL
A.7 PLC user interfaces
Description
Appendix
107