Of the various industrial communication protocols, one protocol that has stood the test of time and is widely used in industrial automation is Profibus. Profibus is a fieldbus communication standard that allows devices to exchange data in real-time, enabling seamless communication between various components in an automated system. The versatility and flexibility of Profibus is further enhanced by utilizing application profiles specific to different industrial applications. In continuation of our articles covering the Physical layer of Profibus and the Fieldbus Data Link layer in this article, we will demystify the application profiles of Profibus and provide you with insights about them.
Profibus Application Profiles
As there are hundreds of manufacturers each coming up with their own Profibus devices, it is important that all these devices speak in a common language and understand each other. And one type of device must be easier to replace with another of the same type. To achieve this interoperability, Profibus International (PI) specifies the application profiles. These profiles are a set of characteristics that devices are expected to support. The profiles are classified into two types – General Application profiles and Special Application profiles based on the application of the same.
General Application profiles also called as the Common Application profiles can be used on more than one application as their characteristics are not tied to one specific use case. Some examples of the same are Time Stamp, PROFIsafe, Redundancy, etc.
Specific Application profiles are those defined for particular use case. Backed by a cross-industry expert team, PI has identified and defined profiles for most of the process automation applications. This enabled quick adoption of Profibus standards and easy cross-operability of devices and controllers. Some of them include ProfiDrive, Profibus PA etc.
Let us have a look at some of the common application profiles in use.
Profibus ProfiDrive Profile
Efficient control of drives is essential in many industrial applications, such as conveyor systems, robotics, and machine tools. Profibus offers a dedicated application profile called ProfiDrive, specifically designed for controlling drives.
ProfiDrive provides standardized communication interfaces and data structures for seamless integration of drive systems into the Profibus network. Right from simple frequency converters to advanced servo controllers, the drive features can be seamlessly mapped to this device profiles. In fact, being one of the most popular profiles in use, it enables precise and synchronized control of drives, allowing for optimized performance, improved energy efficiency, and reduced maintenance costs.
Profibus PA Profile for Process Automation
In process automation applications, accurate and reliable measurement and control are critical. Profibus offers an application profile called PA Devices, which is designed specifically for process automation.
PA Devices provide standardized communication interfaces for various process instruments, such as pressure transmitters, flow meters, and temperature sensors based on function blocks and parameters. Each function block implements one specific functionality. Some of the function blocks are Analog Input Block, Analog Output block, Digital Input and Digital Output blocks. The parameters could be input, output or internal each affecting the operation of the function blocks.
Profibus ProfiSafe Profile
One of the application profiles of Profibus that deserves special attention is ProfiSafe. Safety is of paramount importance in industrial automation, and ProfiSafe provides a comprehensive safety solution for Profibus networks. It allows for the integration of safety devices, such as emergency stop buttons and safety sensors, into the Profibus network.
Designed independent of the underlying physical channel, the ProfiSafe profile handles the encoding and decoding of the data and ensures integrity of the communicated data. The design can support even the most stringent safety requirements up to SIL 3 (Safety Integrity Level). By utilizing ProfiSafe, operators can enhance the safety of their automated systems, reduce the risk of accidents, and comply with safety standards and regulations.
HART on Profibus DP
Another essential aspect of Profibus is its compatibility with the Highway Addressable Remote Transducer (HART) protocol. Profibus DP (Decentralized Periphery) supports the integration of HART devices into the Profibus network, allowing for seamless communication with intelligent field devices.
HART devices provide valuable diagnostic information, such as device health status, process variables, and calibration data and have wide adoption. The HART on Profibus profile allows mapping of client server model of HART on to the Profibus by mapping the HART client as Profibus Master and HART master as Profibus slave.
Profibus Time Stamp Profile
Accurate data synchronization is crucial in many industrial applications, especially in systems where precise timing is required. Profibus provides a time stamping feature that allows devices to synchronize their data transmission based on a common time reference. This feature ensures that data from different devices is aligned in time, enabling accurate data analysis and control.
Profibus's time stamping feature is particularly beneficial when events or alarms occur and need precise timing. The clock master controls the slave clocks over MS3 services.
Profibus Ident Systems Profile
Reliable identification of products, components, and assets is essential in many industrial applications, such as logistics, warehousing, and production tracking. Profibus offers an application profile called Ident Systems, specifically designed for integrating identification devices into the Profibus network.
Ident Systems helps to identify a device with its modules/submodules and provide additional information to support the end user during various scenarios of a device's life cycle. They provide standardized communication interfaces for barcode scanners, RFID readers, and other identification devices.
Diagnostics in Profibus
In any industrial automation system, device diagnostics play a crucial role in ensuring smooth operation and proactive maintenance. The success of Profibus can be attributed to its diagnostics capabilities. With the ability to pinpoint the source of failure, it is easy to fix the issues. By design, the Profibus allows the DP slave to report errors. During the data exchange cycle, the slave can report to the master that it has a diagnostic condition following which the master reads the diagnostic information from it. The information could be of one of standard diagnostics, device-related diagnostics, module-related diagnostics, and channel-related diagnostics formats. It also allows for vendor specific diagnostic information.
By analyzing this diagnostic information, engineers can identify potential issues, predict failures, and take preventive actions. The real-time availability of device diagnostics enables quick troubleshooting, reduces downtime, and improves the overall reliability of the automation system.
Other Profibus Profiles
Some of the other common application profiles defined by Profibus are listed in the below table.
| Name | Application |
|---|---|
| Encoder | For rotary, angular, and linear encoders with single-turn and multi-turn resolution |
| Fluid Power | Control of hydraulic drives via PROFIBUS in cooperation with VDMA |
| Dosing / Weighing | For use of dosing and weighing systems on PROFIBUS |
| Low Voltage Switchgear | For low-voltage switchgear (switch disconnector, motor starter, etc.) on PROFIBUS |
| Remote I/O for PA | For interchangeability of remote I/O devices in process automation |
| Remote I/O for FA | For interchangeability of remote I/O devices in factory automation |
| SEMI | Properties of semiconductor manufacturing devices on PROFIBUS (SEMI standard) |
| Data Types | Data type definitions of profile variables and parameters, programming languages of field devices and controllers |
| Identification & Maintenance | Identification of PROFIBUS devices and Internet access to device-specific information |
| Redundancy | Mechanism for field devices with redundant communication behavior |
Apart from these, there are any more profiles defined by PI and are being used across multiple applications.
Conclusion
In conclusion, the application profiles of Profibus offer a wide range of capabilities to enhance the functionality and performance of industrial automation systems. From safety solutions to precise control and efficient diagnostics, Profibus application profiles provide engineers with the tools they need to optimize their automation systems.
In our next article we will touch up the configuration and setup of Profibus devices including the GSD files. Keep a watch on this space!
