Cable Length Vs. Frequency; Biss C Protocol; Overview; Table 8: Cable Length Vs. Max Clock Frequency (Ssi) - Encoder A36R Technical Reference Manual

Model A36R

7.4 Cable Length vs. Frequency

The maximum clock frequency supplied by the master is limited by cable length.
Cable Length
< 1 m (3.2 ft)
< 35 m (115 ft)
< 60 m (197 ft)
<150 m (492 ft)
< 240 m (787 ft)
> 240 m
Note: This assumes shielded twisted pair cable and proper termination are used. Lower clock frequency may be required at
extreme cable lengths. Although these clock frequencies are possible, limiting frequency for SSI is advised for best performance.

Table 8: Cable length vs. max clock frequency (SSI)

An additional consideration with long cable lengths is voltage drop. Be advised that the minimum specified voltage at +VDC
for this encoder must be met at the encoder. Long cable lengths equate to more voltage dropped on the cable and must be
considered.

8. BiSS C Protocol

8.1 Overview

BiSS C is an open-source digital interface for sensors and actuators. BiSS is hardware compatible with the industrial standard SSI
(Serial Synchronous Interface), but offers additional feature and options:
• Two unidirectional lines
• Cyclic at high speed (up to 10MHz possible using RS422)
• Line delay compensation for high-speed data transfer
• Request processing times for data generation at slaves
• Error checking: CRC, errors, warnings
Model A36R encoders with BiSS C communication are always slave devices. The fieldbus device (i.e., controller, counter) is always
the master device, supplying a clock signal to which the encoder responds synchronously. This uses the same point-to-point
configuration as SSI with two sets of differential signals: Clock and Data.
BiSS C uses Control Data (CD) bits in both the master data stream, Control Data Master (CDM), and the slave data stream, Control
Data Slave (CDS). These bits permit the reading from and writing to slave registers and the sending of commands to slave devices
one bit at a time across multiple data packets.
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Max Clock Frequency
5 MHz
1.7 MHz
1.0 MHz
500 kHz
333 kHz
Not advised. Contact EPC if required.
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T E C H N I C A L R E F E R E N C E M A N U A L
EPC Technical Reference Manual – Model A36R
© 2023 Encoder Products Company, REV 11/08/2023