Siemens S7-300 appendix Technical data

Technical data of CPU 31x 7.2 CPU 312

Technical data
Number of function modules and communication
processors you can operate
•	FM	Max. 8
•	CP (PtP)	Max. 8
•	CP (LAN)	Max. 4
Time-of-day
Real-time clock		Yes (SW clock)
•	Buffered	No
•	Accuracy	Deviation per day < 15 s
• Behavior of the realtime clock after POWER		The clock keeps running, continuing at the time-
	ON	of-day it had when power was switched off.
Operating hours counter		1
•	Number	0
•	Value range	2 31
		(if SFC 101 is used)
•	Granularity	1 hour
•	Retentive	Yes; must be manually restarted after every
		restart
Clock synchronization		Yes
•	In the PLC	Master
•	On MPI	Master/slave
S7 signaling functions
Number of stations that can be logged on for		6
signaling functions		(depends on the number of connections
		configured for PG / OP and S7 basic
		communication)
Process diagnostics messages		Yes
• Simultaneously enabled interrupt S blocks		Max. 20
Testing and commissioning functions
Status/control variables		Yes
•	Variables	Inputs, outputs, memory bits, DBs, timers,
		counters
•	Number of variables	30
	– Of those as status variable	30
	– Of those as control variable	14
Forcing		Yes
•	Variables	Inputs, outputs
•	Number of variables	Max. 10
Block status		Yes
Single step		Yes
Breakpoints		2
Diagnostic buffer		Yes
• Number of entries (not configurable)		Max. 100

CPU 31xC and CPU 31x, Technical data	7-5
Manual, Edition 08/2004, A5E00105475-05