Siemens Simatic S7-300 CPU 31xC and CPU 31x S7-300 - Manual (Page 170)

Technical data of CPU 31x
7.2 CPU 312
CPU 31xC and CPU 31x, Technical data
7-4
Manual, Edition 08/2004, A5E00105475-05
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