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Digital Interfaces RS422
optoNCDT 1420
8. Digital Interfaces RS422
8.1 Preliminary Remarks
The interface RS422 has a maximum baud rate of 1 MBaud. The factory-set baud rate is 921.6 kBaud. The
maximum measuring rate is 4 kHz.
Data format: Measurement values in binary format, commands as an ASCII string.
Interface parameter: 8 Data bits, no parity, one stop bit (8N1).
i
Disconnect or connect the D-sub connection between RS422 and USB converter when the sensor is
disconnected from power supply only.
8.2 Measurement Data Format
16
1
resp. 18 bits are transmitted per output value, see Chap. 7.5.2. An output value is divided into three bytes
that differ in the two most significant bits. The transmission of additional output values is optional.
Output value 1 / additional:
L-Byte 0 0 D5 D4 D3 D2 D1 D0
M-Byte 0 1 D11 D10 D9 D8 D7 D6
H-Byte 1 0
2
0
3
0
3
D15 D14 D13 D12
Output sequence: L-Byte, M-Byte, H-Byte.
1, 3) Error values are coded with 18 Bit.
2) To decide between the 1
st
output value and additional output values, bit 7 in the H-Byte is set to 1. Bit 7 in
the H-Byte is set to 0 for the 1
st
output value. This simultaneously represents the identifier of a new block. De-
pending on the measuring rate, baud rate and output data rate output all data can be output in one block. If
data output is not possible, a run-time error will be output. Use the command GETOUTINFO_RS422 to query
for data selection and output sequence.
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