BiSS Interface – success with the Open Source!

The BiSS interface is required for position sensor technology and for systems controlling motor feedback. This is a free protocol with compatibility to the serial-synchronous interface (SSI). This interface is the version with improved speed and matching of the line length. In addition to position sensor technology, the BiSS interface is also used for drive control and intelligent sensor technology. In the field of position sensor technology, this protocol specifically refers to the rotary encoder and the linear position sensors, both of which are absolute encoders. Furthermore, the scope of application can be expanded to robotics. The specifications of the BiSS interface can be seen when taking a closer look at this interface.

  • The interface can be bidirectional, serial, or synchronous. This characteristic can be summarized under the item “Open Source”. As such, this protocol is freely accessible for various connection options.
  • The reading of the data is cyclic and in real time. This enables a data speed of up to 64 bit per slave during communication between a controller and the sensors on the one hand, and between a controller and the actuators on the other. With the slave (which is also called a master) it is a case of hierarchical management of each access to a medium or a resource on the part of the control unit or regulator. Problems are also processed by these components. This point is also known as isochronous data transmission.
  • The variants of the BiSS interface also include the B-mode and the C-mode. This illustrates the application possibilities for the interface within the field of industrial communication. As such, data concerning the status of a device as well as the parameters are transmitted. Furthermore, the BiSS interface also transmits measured values concerning the temperature as well as descriptions concerning the executed configurations and configurations to be executed.

Special characteristics of the BiSS interface

As a result of these characteristics, the BiSS interface is suited for applications requiring high transmission speeds, high security, high flexibility and an optimally reduced implementation costs. The secured communication aspect takes place via CRC. This is the ‘cyclic redundancy check’, i.e. a cyclic check of the redundancy. This process can be used to determine test values for specific data. This has the advantage that errors that may occur during the transmission and storage of information can be recognized and corrected. It is worth mentioning that CRC-secured communication is a separately occurring safeguarding process for sensor data / control data exists, so that the risk of error can be / shall be minimized again. However, in the field of position sensor technology and motor feedback systems, the BiSS interface has proven itself through further special characteristics. For example, when simultaneous use of the control data is required, the sensor data are transmitted continuously without an interruption of the process. As such, the actuators within the bus can be controlled even when sensor data transmission occurs at the same time. In particular, the aspect of standardization makes the BiSS interface a modern protocol type and a useful component of information technology and industrial communication. This is because the standardization is considerably wider. This is something which can be traced back to the BiSS profile, BiSS USER DATA and the BiSS EDS, i.e. the electronic data sheet. Additionally, the full compatibility of the protocol is stressed with the example of the BiSS identifier.

Developments of the BiSS interface within position sensor technology

In data communication, where communication takes place serially, this free interface quickly became the most popular point-to-point connection, as here, the master and slave can be connected simply and bidirectionally with each other. However, the developments relating to this protocol, particularly in its scope of application (position sensor technology) are considerably more far-reaching. This type of interface was presented first in the year 2002. Both versions, the B-mode as well as the C-mode, were marketed, but with regard to motor feedback systems, the BiSS B-option had a positive resonance. Not suited for motor feedback, the BiSS C-version was put on the back burner. Last year, all patent classes of the B-mode were dropped, including mode switching by frequency comparison, mode switching as such, and the block transmission of additional uncritical data. In addition, in the mean time, multi-cycle data is no longer are being used within the field of position sensor technology. However, as it uses the PHY circuit of the SSI interface, BiSS has developed itself as a successor to the SSI interface. Thus the development span of the BiSS interface is characterised by its beginnings as a simple interface, with the advantage of free use without the restraint of compatibility, through to the possibility of its becoming a successor to other interfaces. As such, Open Source serves as the basis for the development of modern interfaces.