Since PROFINET is the native communication protocol for PCS 7, integrating a PROFINET-enabled device into a PCS 7 distributed control system (DCS) can help foster seamless communication and enhance system performance. Because integration involves more than simply adding the device to the hardware configuration, especially for third-party devices, our team often fields questions on this process. In this post we will review several factors to consider, as well as recommended steps to ensure a smooth process when integrating PROFINET devices into PCS 7.  

Aligning Redundancy Requirements and Device Capabilities

PROFINET has various capability levels and feature sets, and not all devices support the full range of PROFINET redundancy. As a result, during the initial design phase of your project, you must establish both the redundancy level your system requires and the redundancy level your PROFINET devices can support. PROFINET network redundancy levels include the following (see Figure 1):

• S1 – Single PROFINET master, no network or master redundancy. Almost all PROFINET devices will support this level.
• S2 – Dual master network with shared network infrastructure. S2 protocol manages the transition between two PROFINET masters on one IP network. This can be a line or a media redundancy protocol (MRP) ring configuration network.
• R1 – Supports network path redundancy by using two independent networks, each with a single master.
• R2 – Supports dual masters on dual networks. Essentially a combination of S2 and R1 functionality. 

Figure 1. These diagrams represent the device configurations for the four PROFINET network redundancy levels. Source.

Today, most devices support strictly S1 configuration, with some supporting S2, and few supporting R1 or R2. It’s also important to note that redundant PROFINET devices cannot be configured to communicate with non-redundant controllers in a PCS 7 setup. Therefore, to support S2 and S1 devices in your PCS 7-based control system, you must give careful consideration to the hardware configuration and network architecture you need to use. Let’s look at examples of how setups might look for supporting both S2 and S1 devices.

Devices that Support S2 Redundancy

A configuration for devices that support S2 redundancy might look as follows:

• A redundant controller pair is configured as the PROFINET masters in an active-passive setup (one to serve as the primary controller and the other as the backup)
• S2-capable devices are configured to connect to both controllers and each S2 device is assigned to both legs of the PROFINET in the PCS 7 hardware configuration
• If the primary controller fails, the standby controller will automatically assume the master control of the PROFINET devices.

Devices that Do Not Support Redundancy (S1)

S1 devices only support a single connection to one controller, therefore, to achieve redundancy, a gateway with dual-controller connectivity must be configured to communicate between the device and both controllers. This setup provides an alternate path if the primary path for the S1 device fails. Currently, the hardware solution for integration into a redundant PCS 7 system is to use a Simplex PCS 7 controller as the hardware interface, but Siemens has a gateway device on their roadmap that will interface between redundant and non-redundant PROFINET networks.

Devices that Support Network Redundancy (R1)

A configuration for devices that support R1 redundancy might look similar to the S2 configuration with the following differences:

• A redundant controller pair is configured as the PROFINET masters in an active-passive setup (one to serve as the primary controller and the other as the backup), and each controller is connected to a different IP subnet.
• R1-capable devices are configured to connect to both networks, and each R1 device is assigned to both legs of the PROFINET in the PCS 7 hardware configuration. In the R1 configuration these legs are on different IP subnets.
• If the primary controller fails, the standby controller will automatically assume master control of the PROFINET devices.
• If the controllers are configured to support R1 redundancy, and some of the devices support S2 but not R1 configuration, a gateway device is required to connect the S2 devices to both legs of the PROFINET network. This gateway manages the interface of an S2 device which has one IP address, to two separate IP subnets.

Installing Hardware in the PCS 7 Hardware Configuration

Once the design of the PROFINET network is decided upon, and the PROFINET devices are selected, configuration of the PCS 7 system can begin. However, it’s important to know that prior to configuring a PROFINET device that is not included in the Siemens hardware catalog, you must first install the General Station Description (GSD) file.

The GSD file is a standardized configuration file that describes the communication properties and capabilities of the PROFINET device. It includes important information for the device such as supported data types, I/O modules, diagnostics, and configuration parameters so that PCS 7 can recognize and configure the device on the PROFINET network.

A GSD file for a third-party PROFINET device can typically be downloaded from the manufacturer’s website or obtained directly from the vendor and installed in PCS 7 in the hardware configuration tool. After installing the GSD file, the device will appear in the PCS 7 hardware catalog so you can add it to the PROFINET network and configure it.

Configuring Devices

Once the device is installed into the PCS7 catalog, the configuration of the PROFINET devices follows the same configuration procedure as a device that was native to the catalog. First, the device is connected to the PROFINET network by dragging it from the catalog to the network. Then, you can identify and define the data points each device needs to supply and assign I/O addresses in PCS 7. This is done in the hardware configuration by mapping each data point to a specific address or tag that PCS 7 uses to interact with the device. PCS 7 function blocks can also be used as a modular way to interface and process data from PROFINET devices. Additionally, as part of the configuration, you must also ensure critical data points are set to update at appropriate intervals to maintain data consistency.

Establishing Communication Between PCS 7 and I/O Cards

When using I/O cards specifically designed for PCS 7, establishing communication between PCS 7 and individual I/O channels is fairly straightforward. Each I/O card has a unique channel driver, and all channel drivers for Siemens’ I/O modules are pre-integrated into the PCS 7 Advanced Process Library (APL). These I/O cards are automatically recognized by the system, and functions such as data interpretation, diagnostics, channel-specific processing, reading data from input channels, and writing to output channels are easy to establish.

For third-party PROFINET devices, while some smart devices may provide a third-party PCS 7 channel driver, this is the exception and not the rule. This means you will need to develop a custom channel driver or logic to integrate scaling and signal quality into the format your program requires. For devices such as a flowmeter, this driver can be pretty simple, but for more complex devices, such as a smart scale, the driver can be quite complex and time consuming to develop. 

Need Additional Assistance?

As a certified Siemens Solutions Partner, we are well-qualified to help you integrate the latest PROFINET devices into your PCS 7 system. Contact us today to see how we can partner with you to develop customized solutions designed to optimize performance and efficiency.