Baumer_BiSS-C_MA_EN_V1 00.docx
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5 Sensor data communication
The data area
The data area is used to transmit the sensor data from the slaves to the master. The entire data area is
divided into logical data channels. The position and length of the individual data channels is described for
each slave in its parameters. A slave can have no, one or several data channels for sensor data.
Valid data can only be transmitted with a correct configuration of the data channels in the master. The check
bits contained for each data channel are used to detect transmission errors and bit offsets.
The slave data arrive at the master directly after the CDS bit. The further data channels follow without
separation by start or stop bits, so the length of the data area is the sum of the length of all data channels.
The slaves can only correctly signal the BiSS timeout in the BiSS frame if all SLO lines have the signal level
„0“ at the start of the BiSS timeout. The master sends a leading zero before each packet which is active as a
stop bit at the slave output at the end of the cycle. If an error occurs, the BiSS frame can be canceled with a
timeout of 40 μs at any time.
Figure 4
CRC checking
Each data channel can use transmission checking with CRC in addition to its data value. The properties of
the CRC checking are specified in the parameters of the data channel. The CRC polynomial also indicates
the transmitted CRC bits. Calculation is carried out via the data bits and starting with the most significant bit.
There is no start bit. The CRC check bits are always transmitted inversely first with the most significant bit.
The starting value for the CRC calculation is generally zero.
Output format BiSS-C protocol:
CDS
0/1 bit
MT
12 bit
ST
9-19 bit
ERR/NERR
WARN/NWARN CRCPOS
6 bit (inverted)
Figure 5