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SMRA - SSI and BiSS
The output code of the sensor can be GRAY or BINARY (see the order code).
Structure of the transmitted position value:
SMRA-xx-x-06-... bit 13 … 2 1
SMRA-xx-x-07-... bit 14 … 2 1
SMRA-xx-x-08-... bit 15 … 2 1
value MSB … LSB Error bit
5.3 Recommended transmission rates
The SSI interface has a frequency of data transmission ranging between 100 kHz
and 2 MHz.
The CLOCK signals and the DATA signals comply with the “EIA standard RS-422”.
The clock frequency (baud rate) depends on the length of the cable and must
comply with the technical information reported in the following table:
Cable length Baud rate
< 60 m < 400 kHz
< 100 m < 300 kHz
< 200 m < 200 kHz
< 400 m < 100 kHz
The time interval between two Clock sequence transmissions must be at least 16
µs ( Tp = pause time > 16 µs).
5.4 Error bit
The error bit is intended to communicate the normal or fault status of the Slave.
“1”:
correct status (the sensor is working properly, there are no active
errors)
“0”: an error is active:
•
position calculation error, invalid position value; the sensing
electronics is not able to read the ring; this problem may be
caused, for instance, by an excessive distance between the
sensor and the ring, by a wrong/reversed assembly of the
elements, by a damage to the magnetic surface of the ring;see
the section “3.3.2 Mounting the sensor“ on page 12;
•
the power supply is not as required, please refer to the order
code;
•
EEPROM error.
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