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

Cycle and response times
7.2 Cycle time
7.2 7.2 Cycle time
7.2.1 Overview
Introduction
This chapter explains what we mean by the term "cycle time", what it consists of, and how
you can calculate it.
Meaning of the term cycle time
The cycle time represents the time that an operating system needs to execute a program,
that is, one OB 1 cycle, including all program sections and system activities interrupting this
cycle.
This time is monitored.
Time-Sharing Model
Cyclic program processing, and therefore user program execution, is based on time shares.
To clarify these processes, let us assume that every time share has a length of precisely
1 ms.
Process image
During cyclic program processing, the CPU requires a consistent image of the process
signals. To ensure this, the process signals are read/written prior to program execution.
Subsequently, the CPU does not address input (I) and output (Q) address areas directly at
the signal modules, but rather accesses the system memory area containing the I/O process
image.
S7-300 CPU Data: CPU 315T-2 DP
7-2 Manual, 12/2005, A5E00427933-02

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