User Manual

3. Installation
3−12
Festo GDCP−SFC−LACI−DN−EN en 0812NH
Displacement encoder for BiSS interface
The BiSS interface is a 2−wire interface for interference−im
mune sensor connection. In contrast to the SSI interface, the
data transmission is bi−d
irectional, which means, for example,
that data can also be written into the sensor for parametrisa
tion.
Data is transmitted via a pulse cable contr
olled by the master
and a data cable controlled by the sensor as serial trans
mission. Data is written to the slave via the cycle’s pulse
width modul
ation in accordance with the "BiSS B mode" pro
tocol specification http://www.biss−ic.de/files/
BiSS_b3ds.pdf; the direc¬tion of the data cable is not
switched.
Pulse and data are transmitted using RS485 tech
nology, which means a signal is sent not−inverted as well as
inverted and issued at the receiver as diff
erential input. This
suppresses common−mode interference. The data are also
secured by a CRC code.
The BiSS interface supports 2 read−out modes:
The
sensor data channel for fast pulse out (pulse up to 10
MHz) of the sensor information
The parameter channel for reading and writing sensor
parameters
as well as for depositing user−specific data
protected against zero voltage in the sensor’s EEPROM
The distinction is made on the basis of the start
bit, details
can be referred to in the specifications given.