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

Technical data of CPU 31x 7.2 CPU 312

Technical data

Data areas and their retentivity

Flag bits		128 bytes
•	Retentive memory	Yes
•	Default retentivity	MB0 to MB15
Clock flag bits		8 (1 byte per flag bit)
Data blocks		511
		(DB 1 to DB 511)
•	Length	16 KB
Local data per priority class		max. 256 bytes
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	max. 16 KB
Nesting depth
•	Per priority class	8
• additional within an error OB		4
FBs		Max. 512
		(FB 0 to FB 511)
•	Length	max. 16 KB
FCs		Max. 512
		(FC 0 to FC 511
•	Length	max. 16 KB
Address areas (I/O)
Total I/O address area		1024 bytes /1024 bytes
		(can be freely addressed)
I/O process image		128 bytes/128 bytes
Digital channels		Max. 256
of those local		Max. 256
Analog channels		Max. 64
of those local		Max. 64
Assembly
Racks		Max. 1
Modules per rack		Max. 8
Number of DP masters
•	Integrated	None
•	Via CP	1

7-4	CPU 31xC and CPU 31x, Technical data
	Manual, Edition 08/2004, A5E00105475-05