3.1. Measuring sequence and measuring method

• Measuring sequence

The sequence of the measurement was as follows:

1. Setup of a configuration

2. Measurement of all measured variables Each measurement was repeated 500 times.

3. Evaluation of the measurements Determination of the mean value of the 500 series of measurements for minimum, typical and maximum value

• Measuring method for the performance data
  • PN/DP response time:

One ET200 measurement station is really connected to PROFIBUS DP. The remaining ET200 stations are simulated in wired as well as in wireless connection.
A signal status change is periodically created at an input of the ET200 measurement stations (DIx). The IO controller reads this input and sets an output (DOy) of the ET200 measurement station.
The time interval between both signal status changes is measured with a measuring instrument and stored.

• PN update rate:

This is the typical interval between two IO cycles of the IO controller. This value is calculated by STEP 7 and not measured.

• Cycle time:

The cycle time is measured in the IO controller.
It is determined during the measurement of the response time, thus when the IO controller communicates with the distributed stations.
The IO controller determines the cycle time after each cycle using the start information of OB1.