The BiSS Interface (bidirectional/serial/synchronous) protocol is an – Open Source – digital interface which enables a digital, serial and secure communication between controller, sensor and actuator.
The BiSS protocol is used on the lower sensor/actuator communication level in industrial applications which require transfer rates, safety, flexibility and a minimized implementation effort.
BiSS is hardware compatible to the industrial standard SSI (Serial Synchronous Interface) but offers additional features and options:
Bidirectional Data Communication
Serial synchronous, continuous data communication
Two unidirectional lines Clock and Data
Cyclic at high speed (up to 10 MHz with RS422 and 100 MHz with LVDS)
Line delay compensation for high speed data transfer
Request processing times for data generation at slaves
Safety capable: CRC, Errors, Warnings
Operate actuators via additional MO line (master to slave)
BiSS operates synchronously, serially and cyclically via two unidirectional lines. As the main feature BiSS in addition communicates continuously bidirectional (BiSS is the synonym for BiSS C; C = Continuously).
A typical setup of a BiSS system with a drive/PLC (BiSS master) and encoder (BiSS slave) is shown in Figure 1.
Figure 1: BiSS Interface, point-to-point.
The position data is sent over a single cable from the BiSS slave on the right to the BiSS master on the left. The standard drive contains the blocks ”BiSS Master” and ”RS-422 Bus Transceiver” as well as the encoder contains the blocks ”BiSS Slave” and ”RS-422 Bus Transceiver”. The sensor that generates the position word can be a single chip solution or a set of separate encoder-iCs. The position data, the status and CRC values are evaluated in the BiSS master.
Digital Sensor and Actuator Interface
The BiSS Interface line signals on clock line MA and data return line SLO.
BiSS Line uses the core BiSS definitions and device content but maps the communication on an RS485 half duplex line. The BiSS Line protocol is usable with a 2-wire or 4-wire setup. The 2-wire setup combines communication and power supply on a single twisted pair of lines. BiSS Line provides multi device capability and forward error correction (FEC).
Safety-critical applications targeting up to SIL3 can now be fully covered by BiSS Safety and the BiSS interface. The safety communication level "BiSS Safety" is certified by TÜV Rheinland and follows in extracts the requirements stated in DIN EN 61784-3:2011 and can be used in safety applications up to SIL3 according IEC61508:2010.