Overview of the program components

3.4.1. Overview of the program components

The STEP7 program of the S7 controller consists of the program components:

Measuring program
Load program

Both program components are always loaded during measurement.

Measuring program

The measuring program is composed of:

Communication program:
The STEP 7 components contained here can also be found in real applications.
Acquisition program for measured values:
The STEP 7 components contained here are exclusively used for the acquisition of measured values.

Load program

The load program does not perform specific tasks, it is only used for loads for the S7 controller. Different load programs cause different cycle times of the S7 controller.

The following table gives an overview of the elements belonging to STEP 7 program:

STEP 7 program component		Tasks in the sending station	Tasks in the receiving station
Measuring program	Communication program	Sending of data (in OB1)	Receiving of data (in OB1)
Measuring program	Acquisition program for measured values	- Waiting for the start signal - Measuring the cycle time	- Measuring the cycle time - Generating the ready signal
Load program		No concrete task; is used for loads for the S7 controller (in OB1)	No concrete task; is used for loads for the S7 controller (in OB1)

Composition of the cycle time

The figure below shows the structure of the STEP7 programs and the cycle time in the S7 CPU: