The process of a measurement is as follows:
- Planning and designing a configuration
- Measuring all measured variables (each measurement is repeated several times)
- Evaluating the measurements
Determining the statistical parameters of position
One ET200 measurement station is really connected to PROFIBUS DP. The remaining ET200 stations are simulated.
A signal status change is periodically generated at an input of the ET200 measurement stations (DIx). The DP master reads this input via the process image and sets an output (DOy) of the ET200 measurement station. Using a second automatic measurement station, an input that can trigger a process alarm (OB40) is set in the same way. The output is set via direct commands.
The interval between these two signal status changes is detected and saved with the measuring instruments.
The reaction time with H-CPUs ist measured like with standard DPmaster CPUs. But in this case you can select the corresponding reaction times in the H-CPU status "redundant" and "solo". To simplify this differentiation for the user the H-status is selectable as a own cpu type.
- Cycle time:
The cycle time is measured in the DP master.
It is determined while measuring the DP reaction time, i.e. when the DP master communicates with the distributed stations.
Using the start information of OB1, the DP master determines the cycle time after each cycle.
- HMI operating time:
On an HMI panel, the pressing of a button is triggered via a globe valve. An output is then set on the ET200 measurement station.
The measuring instrument measures the time difference between the two events.
- HMI update time:
On the ET200 measurement station, a signal change is triggered at an input. A light-sensitive sensor records a subsequent change in color on an HMI panel.
The interval between the two events is measured with a measuring instrument.
- PPC operating time:
Like "HMI operating time" - the difference being that the signals are measured on the PanelPC.
For "ENHANCED" configuration: An archive is read out during the process.
- PPC update time:
Like "HMI update time" - the difference being that the signals are measured on the PanelPC.
For "ENHANCED" configuration: An archive is read out during the process.
Notes:
"ENHANCED" configuration of a WinCC flex Runtime HMI on the DP master (Panel PC): The measured values are acquired while reading out an archive. See chapter 3.5
Possible delay times of the used sensors were considered. The signals between measuring instrument and measuring setup are exchanged via process alarms so that measuring errors are minimized.