CPUs
Configuration
Rack
1
Modules per module rack
max. 8
Number of DP masters
S
integral
No
S
via CP
1
S7 message functions
Simultaneously active
None
Alarm-S blocks
Time
Real-time clock
Yes
S
Backed-up
No
S
Accuracy
See Section 1.1.6
Operating hours counter
1
S
Number
0
S
Value range
0 to 32767 hours
S
Selectivity
1 hour
S
Retentive
Yes
Clock synchronisation
Yes
S
On PLC
Master
S
On MPI
Master/Slave
Testing and commissioning functions
Status/Modify Variables
Yes
S
Variable
Inputs, outputs, flags, DBs,
timers, counters
S
Number
–
Monitor Variables
max. 30
max. 14
–
Modify Variables
Force
Yes
S
Variable
Inputs, outputs
S
Number
max. 10
Monitor block
Yes
Single sequence
Yes
Breakpoint
2
Diagnostic buffer
Yes
S
Number of entries
100
(non-alterable)
1-38
Communication functions
PD/OP communication
Global data communication
S
Number of GD packets
–
Sender
–
Receiver
S
Size of GD packets
–
Number of which
consistent
S7 basic communication
S
User data per job
–
Number of which
consistent
S7 communication
S
User data per job
–
Number of which
consistent
S7-compatible
communication
Standard communication
Number of connection
resources
S
Reservation for
–
PD communication
User-definable
Default
–
OP communication
User-definable
Default
–
S7 basic
communication
User-definable
Default
Interfaces
1. Interface
Functionality
S
MPI
S
DP Master
S
DP Slave
S
Galvanically isolated
PLC S7-300, CPU Specifications CPU 312 IFM to CPU 318-2 DP
Yes
Yes
1
1
max. 22 bytes
8 bytes
Yes
max. 76 bytes
32 bytes for X/I_PUT/_GET;
76 bytes for
X_SEND/_RCV
Yes (server)
max. 160 bytes
32 bytes
No
No
8 for PD/OP/S7 basic/S7
communication
max. 7
from 1 to 7
1
max. 7
from 1 to 7
1
max. 4
from 0 to 4
4
Yes
No
No
No
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