Siemens SIMATIC S7-300 CPU Data: CPU 315-T-2 DP User Manual

Cycle and response times
7.2 Cycle time
7.2.4 Communication Load
Configured communication load (PG/OP communication)
The CPU operating system continuously provides a specified percentage of total CPU
processing performance (time-sharing technology) for communication tasks. Processing
performance not required for communication is made available to other processes.
In the hardware configuration, you can set the load due to communications between 5% and
50%. Default value is 20%.
You can use the following formula for calculating the cycle time extension factor:
100 / (100 - configured communication load in %)
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Figure 7-3 Breakdown of a time slice
Example: 20% communication load
You have configured a communication load of 20% in the hardware configuration.
The calculated cycle time is 10 ms.
Using the above formula, the cycle time is extended by the factor 1.25.
Example: 50 % communication load
You have configured a communication load of 50 % in the hardware configuration.
The calculated cycle time is 10 ms.
Using the above formula, the cycle time is extended by the factor 2.
S7-300 CPU Data: CPU 315T-2 DP
Manual, 12/2005, A5E00427933-02
7-7

Siemens SIMATIC S7-300 CPU Data: CPU 315-T-2 DP Specifications

General

Programming Language	STEP 7
Power Supply	24 V DC
Number of DP masters	1
Processable Technology objects	Yes
Number of counters	256
Number of timers	256
S7 communication	Yes
Number of connections for S7 communication, max.	16
PG/OP communication	Yes
Global data communication	Yes
Integrated DP interface	Yes
Integrated PROFINET interface	No
SIMATIC Computing Platform	No
Operating Temperature	0 to 60 °C
Integrated Interfaces	MPI, DP
Communication	PROFIBUS DP
Cycle Time	0.1 ms
Engineering with	STEP 7
Backup available	Yes
Transmission rate, max.	12 Mbit/s