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COMMERCIAL CARBON DIOXIDE SENSOR, 400 PPM TO
2000 PPM (UP TO 5000 PPM EXTENDED RANGE),
8.0
MODBUS FUNCTION DESCRIPTION
The serial port configuration is: 9600, 8, 1, N, N.
8.1
Input Registers Description
Values are read from IR using "Read input registers" (function code 04).
8.1.1
Read Detector Temperature
Master Transmit:
<FE> <04> <00> <04> <00> <01> <64> <04>
Slave Reply:
<FE> <04> <02>
<30> <D4>
Data Explain:
<30> <D4> is valid data 0x30D4, decimal is 12500. After conversion (divided by 100 first, then subtract 100), it is 25 degrees
Celsius. Note that the detector temperature is usually higher than the ambient temperature.
8.1.2
Read Meter Status
Master Transmit:
<FE> <04> <00> <05> <00> <01> <35> <C4>
Slave Reply:
<FE> <04> <02>
<01> <60>
Data Explain:
<01> <60> is valid data
0x0160, the binary is 0b101100000, the 0th bit of the data bit is DI1, the first bit of the data bit is DI2, and
so on. The valid bits are as follows:
DI 6 - Out of Range
DI 7 - Memory error
8.1.3
Read Output Status
Master Transmit:
<FE> <04> <00> <06> <00> <01> <C5 > <C4>
Slave Reply:
<FE> <04> <02>
<00> <03>
Data Explain:
<00> <03> is valid data 0x0003, the binary is 0b11. The valid bits are as follows:
DI 1 - Alarm Output status (inverted due to Open Collector)
DI 2 - PWM Output status (1 means full output)
8.1.4
Read Space CO
2
Master Transmit:
<FE> <04> <00> <07> <00> <01> <94 > <04>
Slave Reply:
<FE> <04> <02>
<01> <90>
Data Explain:
<01> <90> is valid data 0x0190, decimal is 400 ppm.
8.1.5
Read PWM Output
Master Transmit:
<FE> <04> <00> <08> <00> <01> <A4 > <07>
Slave Reply:
<FE> <04> <02>
<3F> <FF>
Data Explain:
<3F> <FF> is valid data 0x3FFF, it represents 100% output, i.e. 2000 ppm CO
8.1.6
Read Sensor Type ID
Master Transmit:
<FE> <04> <00> <09> <00> <02> <B5> <C6>
Slave Reply:
<FE> <04> <04>
<00> <00> <18> <00>
Data Explain:
<00> <00> <18> <00> is valid data 0x00001800, IR09 low byte + IR10 contains Sensor Type ID 3-bytes value, so this data is
0x001800, it indicates the type of sensor.
The sensor is addressed as "Any address" (0xFE).
<51> <9A>
<AC> <9C>
<ED> <25>
<AC> <D8>
<FC> <94>
<FE> <8B>
CRIR E1
.
2
Sensing and Internet of Things
Issue 1
000841
9
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