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NOTICE
For obtaining the correct floating point values, both registers have to be read within the same reading
cycle. The measured value can change between two Modbus requests, exponent and mantissa may get
inconsistent then.
Communication settings (INT16)
Parameter
Write register: function code 0x06
Modbus address
Modbus protocol settings
Device information (INT16)
Parameter
Read register: function code 0x03 / 0x04
Serial number (as ASCII)
Firmware version
Sensor name (as ASCII)
Device status (bit decoded)
1) Register number starts from 1.
2) Protocol address starts from 0.
3) For Modbus protocol settings see Application Note Modbus AN0103 (available at www.epluse.com/cds201).
4) See chapter 5.5 Device Status Indication.
Tab. 4
CDS201 registers for device setup
5.2.5.
Modbus Register Map
The measured data is saved as a 32 bit floating point values (data type FLOAT32) and as 16 bit signed integer
values (data type INT16).
FLOAT32
Parameter
Read register: function code 0x03 / 0x04
Temperature T
Relative humidity RH, Uw
CO
average
2
CO
raw
2
Dew point temperature Td
Register number
3)
Register number
4)
1)
Unit
Register number
°C
°F
K
%
ppm
ppm
°C
°F
°K
1)
[Dec]
1
2
1)
[Dec]
1
9
10
602
2)
[DEC]
1003
1005
1009
1021
1061
1063
1105
1107
1147
User Manual CDS201
2)
Register address
[Hex]
0x00
0x01
2)
Register address
[Hex]
0x00
0x08
0x09
0x259
3)
Register address
[HEX]
0x3EA
0x3EC
0x3F0
0x3FC
0x424
0x426
0x450
0x452
0x47A
CO
, Humidity and Temperature Room Sensor | 14
2
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