Si-Universal Encoder User Guide Issue - Emerson SI-Universal User Manual

3.4.5 Comms only, (absolute encoders) SSI and EnDat
Type Encoder
EnDat
Comms
SSI
(absolute)
BiSS*
The SSI (Synchronous Serial Interface), EnDat (Encoder Data) and BiSS (Bi-directional
Synchronous Serial) encoders have a serial link between the encoder and drive which passes all
positional information.
NOTE
It should be noted that EnDat, BiSS and SSI encoders must be initialized before their position data
can be used. The encoder is automatically initialized at power-up after trips 100 - 135 are reset, or
when the initialization parameter (Pr 1x.075) is set to 1.
SSI, EnDat, BiSS*
The interfaces transmit data synchronised with a CLOCK signal provided from the drive. This
makes it possible to transmit position values quickly and reliably with only four signal lines.
The main difference between the SSI and the EnDat/BiSS being that the standard SSI encoder is
Uni-directional whereas the EnDat and BiSS are Bi-directional. The data transfer for both the SSI,
BiSS and the EnDat use the 485 standard for data and clock signals.
Type
Comms Only
NOTE
The SSI input at default is configured to operate in Gray code, this can be changed to binary format
by setting Pr 1x.048= 1.
NOTE
A flux alignment test is required during set up to determine the phase offset angle for operation in
RFC-S mode.
* BiSS is not currently supported.
SI-Universal Encoder User Guide
Issue: 2
Description
Absolute EnDat only encoder
Additional communications with the
encoder is not possible.
Absolute SSI only encoder.
Additional communications with the
encoder is not possible.
Absolute BiSS C mode only encoder
Additional communications with the
encoder is not possible
Limitations
Encoder
EnDat
SSI
BiSS*
Pr 1x.038
8
10
13
Max Baud
Rate (bits/sec)
4 Mbits/sec
Pr 2x.038
4
5
6
Max Speed
rpm
50,000 rpm
15