Siemens S7-300 appendix Technical data Data areas and their retentivity

Technical data of CPU 31x 7.3 CPU 314

Technical data

Data areas and their retentivity

Flag bits		256 bytes
•	Retentive memory	Yes
•	Default retentivity	MB0 to MB15
Clock flag bits		8 (1 byte per flag bit)
Data blocks
•	Number	511
		(DB 1 to DB 511)
•	Length	16 KB
Local data per priority class		Max. 510
Blocks
Total		1024 (DBs, FCs, FBs)
		The maximum number of blocks that can be
		loaded may be reduced if you are using another
		MMC.
OBs		See the Instruction List
•	Length	16 KB
Nesting depth
•	Per priority class	8
• additional within an error OB		4
FBs		See the Instruction List
•	Number	512
		(FB 0 to FB 511)
•	Length	16 KB
FCs		See the Instruction List
•	Number	512
		(FC 0 to FC 511)
•	Length	16 KB
Address areas (I/O)
Total I/O address area		Max. 1024 bytes/1024 bytes (can be freely
		addressed)
I/O process image		128 bytes/128 bytes
Digital channels		Max. 1024
of those local		Max. 1024
Analog channels		Max. 256
of those local		Max. 256
Assembly
Racks		Max. 4
Modules per rack		8
Number of DP masters
•	Integrated	None
•	via CP	Max. 1

CPU 31xC and CPU 31x, Technical data	7-9
Manual, Edition 08/2004, A5E00105475-05