3.3.1. Overview of cycle times

The figure below shows the structure of the STEP7 programs and cycle times in the different DP master types:

STEP 7 program:

The STEP7 program consists of two parts:

• User program:

It contains STEP 7 blocks for automating the measurement and for communicating with the distributed stations.
The user program performs the following tasks:

• Function program:
  Program parts that have nothing to do with the actual measured-value acquisition. (E.g., call of communication blocks, HMI program, etc.)
• Acquisition program:
  Program parts that are used exclusively for acquiring the measured values and for generating the control signals.

• Load program:

The load program does not perform specific tasks; the actual program has no function.
It is merely used to increase the size of the STEP 7 program and to thus extend the cycle time.

"Minimum wait time" of WinAC:

The "minimum wait time" parameter of WinAC is a system parameter. It is required to be able to run other applications or operating system functions on the PC in addition to WinAC.

To achieve a practical PC workload of approx. 50 %, the minimum wait time is parameterized for the measurements as follows:
Minimum wait time = execution time.