Emerson SI-Universal User Manual page 65

BiSS C Mode*
BiSS is a synchronous bi-directional communications protocol that is intended to be used alone. It
is possible to obtain position feedback at the same time as communicating with the encoder for
data transfer. A CRC is provided for error checking. The BiSS C frame must comply with the
following restrictions:
• No unused bits between the multi turn and single turn bits.
• 1 error bit and 1 warning bit between the position bits and CRC
• No other information such as life counters
• 6-bit CRC with polynomial 0x43 and starting value of 0x00.
Figure 7-5 BiSS C communication protocol
CDS LeadingZ eroes (LZ)
x x.033 = Number of
LZ bits (if required)
CDS LeadingZ eroes (LZ)
xx.033 = Number of LZ bits (if required) + MT bits
SSI
SSI is a uni-directional communications protocol that is intended to be used alone. It is only
possible to obtain the position information from the encoder and it is not possible to transfer data
between the drive and the encoder. No error checking is provided by the SSI protocol, and so
encoders based on this interface are not recommended for new applications.
Other:
Drive P1
Drive P1 is used to allow the SI-Universal Encoder module to provide hardware encoder simulation
output with scaling using the P1 position interface on the drive as the source. In this mode, the P1
position interface on the SI-Universal Encoder module is disabled and cannot be used as an
interface for a position feedback device. In all other conditions, the P1 position interface on the
module is available for use as a position feedback interface.
The table below details the availability of the P1 position interface for the different types of encoder
simulation output.
* BiSS is not currently supported.
SI-Universal Encoder User Guide
Issue: 2
xx.035 = Number of L Z bits + S T bits + AL bits
S ingle Turn position (ST)
Single Turn encoders
xx.035 = Numberof LZ bits + S T bits + MT bits + AL bits
Multi Turn position (MT) S ingle Turn position (ST)
No unused bits
Multi T urn encoders
Alignments bits (AL)
E rr W ar
(if required)
No life counters or
additional information
Alignments bits (AL) E rr W ar
(if required)
No life counters or
additional information
6bit CRC
6bit CRC
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