Automation projects often require intensive data exchange between SIMATIC S7 controllers and PC systems. On the PC the standardized OPC server has long been established as a central communication component within the PLC world. The OPC server of SIMATIC NET controls many protocols, interfaces and communication paths. To be able to make the right selections in the concept phase of an automation project, it is important to be able to assess the communication performance of a planned configuration.
Important questions in this context are listed below:
- Which S7 components are best suited for the planned automation project?
- Which data transfer times are expected for typical configurations and systems?
- Which statistical fluctuations can occur?
- How does the data communication affect the cycle (OB1) of an S7 controller?
- How do the various OPC interfaces differ respectively?
The figure below illustrates the problem:
To answer the questions above measurements with typical, practice-relevant configurations with SIMATIC components were performed:
- with typical S7 components (controllers) and industrial PCs
- with typical parameters and configurations
- Load programs with practical relevance in the corresponding S7 controllers enable values under real conditions
The focus of this measurement is on the measurement of the runtime of a message frame through the entire system. This means from the S7 station via the SIMATIC NET OPC server to the OPC client application!
A simple user interface of a web application provides you with the results of the measurements. To correctly interpret the measured values, we recommend referring to the boundary conditions of the measurement in the integrated online help.
Overview of the measured variables:
- Monitoring variables
|Time between the modification of n variables in the S7 station until complete transmission of the update in the OPC client.|
- Async Read/ UA Read
|Time between the read request of n variables from the S7 station until complete arrival and acknowledgement in the OPC client.|
- Async Write/ UA Write
|Time between the write request of n variables to the S7 station until complete acknowledgement in the OPC client.|
- Block Send (PLC -> PC)
|Time between the synchronized triggered BSEND in n S7 stations until complete arrival of all data in the OPC client.|
- Block Send (PC -> PLC)
|Time between the triggered BSEND to all S7 stations in the OPC client until complete acknowledgement of all requests.|
|Cycle time S7 CPU
||Time between two cycles in the S7 controller.|
Outputs on the user interface
You can enter the desired configuration quickly and easily with an interactive user interface. The corresponding performance data is available immediately in the output table.
Access to the performance data
Click the respective version to go to the web interface of the performance data.
|Link to all available communication performance data