What products are involved?

Rheonics SRV viscometer, SRD density-viscosity meter, DVP gas density-viscosity meter and DVM HPHT density-viscosity meter

What is the purpose of this article?

To guide the integration of Rheonics SME with an S7-300 controller based on TIA Portal using a Profinet communication protocol.

1. PROFINET Overview

PROFINET is one of the most commonly used industrial communication protocols, it enables data exchange between controllers and devices based on international standards. To link all the components in its network, PROFINET requires standard Ethernet as the communication medium. It can operate on higher transmission speeds than other protocols.

Figure 1. Profinet communication diagram for S7-300

2. GSDML File compatible with S7-300

Startup mode plays a crucial role in how a device establishes communication with a PLC. Modern systems use Advanced mode to enable enhanced features such as faster device initialization, real-time diagnostics, and improved data handling, which allow for quicker error detection and higher data throughput. However, older CPUs like the Siemens S7-300 only support Legacy mode, which lacks these advanced capabilities. To ensure compatibility with such systems, Rheonics developed a GSDML file that allows their viscometers to operate in Legacy mode, ensuring seamless communication with older PLCs while maintaining reliable performance.

Figure 2. GSDML file compatible with S7-300

3. Adding a Rheonics device

3.1. Open a project.

3.2. Select [Manage general station description files (GSD)] in the [Options] menu.
Figure 3. Screenshot of GSD file upload in TIA portal.

3.3. Select the file: GSDML-V2.4-Rheonics-SMET-Legacy-20220321.xml, load, and install this file. 
Figure 4. Screenshot of GSD file upload in TIA portal.
3.4. A new device is added to the project and the sensor memory addresses are assigned.  

Figure 5. Rheonics device in TIA portal.

4. Reading parameters

When integrating a sensor with a Siemens S7-300 PLC, reading hardware I/O as a peripheral is required. To do this, a ":P" must be appended to the tag’s test string. This step is specific to the S7-300 architecture, which necessitates peripheral addressing for certain hardware reads.

In contrast, newer Siemens PLCs, such as those designed for the TIA Portal environment, do not require this process. These PLCs support direct I/O reading without the need for peripheral addressing, simplifying the configuration.

Figure 6. Reading parameters as a peripheral.

By ensuring the correct peripheral addressing the PLC can accurately read sensor data. Once this configuration is properly set, the data can be efficiently transferred to memory and used for process control, enabling smooth and reliable system operation.

5. Resources

Taking the PROFINET road with Rheonics SME