Siemens SIMATIC S7-300 Series Reference Manual page 54

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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