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Modbus Gas Register Map


This document provides a register map for all the gas related registers in the Modbus Base Unit. The map includes information on the various registers used to store gas concentration data, as well as calibration and sensitivity values. In addition to the register map, this document provides a brief introduction to the gas sensor and its capabilities.

Data Registers

Note on Gas Sensitivity

⚠️
It is generally not advisable to directly adjust the sensitivity of gas sensors. Instead, it is recommended to use gas calibration or the offset factor and constant registers to fine-tune the gas sensor data.

Name
Address (16 bit)
Address (10 bit)
Type
Unit
# Registers
Access
Default Value
CO₂
0x00A0
160
f32
ppm
2
read
NaN
CO₂ 1 hour average
0x00A2
162
f32
ppm
2
read
NaN
CO₂ offset factor
0x00A4
164
f32
2
read/write
1
CO₂ offset constant
0x00A6
166
f32
2
read/write
0
NO₂
0x00C0
192
f32
µg/m³
2
read
NaN
NO₂ 1 hour average
0x00C2
194
f32
µg/m³
2
read
NaN
NO₂ offset factor
0x00C4
196
f32
2
read/write
1
NO₂ offset constant
0x00C6
198
f32
2
read/write
0
NO₂ ce current offset
0x00C8
200
f32
2
read/write
0
NO₂ sensitivity
0x00CA
202
f32
nA/ppm
2
read/write
123
CO
0x00E0
224
f32
mg/m³
2
read
NaN
CO 8 hour average
0x00E2
226
f32
mg/m³
2
read
NaN
CO offset factor
0x00E4
228
f32
2
read/write
1
CO offset constant
0x00E6
230
f32
2
read/write
0
CO current offset
0x00E8
232
f32
2
read/write
0
CO sensitivity
0x00EA
234
f32
nA/ppm
2
read/write
123
O₃
0x0100
256
f32
µg/m³
2
read
NaN
O₃ 1 hour average
0x0102
258
f32
µg/m³
2
read
NaN
O₃ 8 hour average
0x0104
260
f32
µg/m³
2
read
NaN
O₃ offset factor
0x0106
262
f32
2
read/write
1
O₃ offset constant
0x0108
264
f32
2
read/write
0
O₃ sensitivity
0x010A
266
f32
2
read/write
123
O₃ NO₂ sensitivity
0x010C
268
f32
2
read/write
123
SO₂
0x0120
288
f32
µg/m³
2
read
NaN
SO₂ 1 hour average
0x0122
290
f32
µg/m³
2
read
NaN
SO₂ 24 hour average
0x0124
292
f32
µg/m³
2
read
NaN
SO₂ offset factor
0x0126
294
f32
2
read/write
1
SO₂ offset constant
0x0128
296
f32
2
read/write
0
SO₂ sensitivity
0x012A
298
f32
nA/ppm
2
read/write
123
NO
0x01A0
416
f32
µg/m³
2
read
NaN
NO 1 hour average
0x01A2
418
f32
µg/m³
2
read
NaN
NO offset factor
0x01A4
420
f32
2
read/write
1
NO offset constant
0x01A6
422
f32
2
read/write
0
NO sensitivity
0x01A8
424
f32
nA/ppm
2
read/write
123

CO₂ (Address = 0x00A0)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x00A0
160
f32
ppm
2
read
NaN
This register contains the CO₂ value retrieved from the most recent poll.

CO₂ 1 hour average (Address = 0x00A2)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x00A2
162
f32
ppm
2
read
NaN
This register contains the 1-hour average CO₂ value.

CO₂ offset factor (Address = 0x00A4)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x00A4
164
f32
2
read/write
1
This register represents the CO₂ offset factor.

CO₂ offset constant (Address = 0x00A6)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x00A6
166
f32
2
read/write
0
This register represents the CO₂ offset constant.

NO₂ (Address = 0x00C0)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x00C0
192
f32
µg/m³
2
read
NaN
This register contains the NO₂ value retrieved from the most recent poll.

NO₂ 1 hour average (Address = 0x00C2)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x00C2
194
f32
µg/m³
2
read
NaN
This register contains the 1-hour average NO₂ value.

NO₂ offset factor (Address = 0x00C4)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x00C4
196
f32
2
read/write
1
This register represents the NO₂ offset factor.

NO₂ offset constant (Address = 0x00C6)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x00C6
198
f32
2
read/write
0
This register represents the NO₂ offset constant.

NO₂ ce current offset (Address = 0x00C8)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x00C8
200
f32
2
read/write
0
This register represents the NO₂ ce current offset.

NO₂ sensitivity (Address = 0x00CA)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x00CA
202
f32
nA/ppm
2
read/write
0
This register represents the sensitivity of NO₂.

CO (Address = 0x00E0)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x00E0
224
f32
mg/m³
2
read
NaN
This register contains the CO value retrieved from the most recent poll.

CO 8 hour average (Address = 0x00E2)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x00E2
226
f32
mg/m³
2
read
NaN
This register contains the 8-hour average CO value.

CO offset factor (Address = 0x00E4)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x00E4
228
f32
2
read/write
1
This register represents the CO offset factor.

CO offset constant (Address = 0x00E6)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x00E6
230
f32
2
read/write
0
This register represents the CO offset constant.

CO current offset (Address = 0x00E8)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x00E8
232
f32
2
read/write
0
This register represents the CO current offset.

CO sensitivity (Address = 0x00EA)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x00EA
234
f32
nA/ppm
2
read/write
0
This register represents the sensitivity of CO.

O₃ (Address = 0x0100)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x0100
256
f32
µg/m³
2
read
NaN
This register contains the O₃ value retrieved from the most recent poll.

O₃ 1 hour average (Address = 0x0102)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x0102
258
f32
µg/m³
2
read
NaN
This register contains the 1-hour average O₃ value.

O₃ 8 hour average (Address = 0x0104)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x0104
260
f32
µg/m³
2
read
NaN
This register contains the 8-hour average O₃ value.

O₃ offset factor (Address = 0x0106)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x0106
262
f32
2
read/write
1
This register represents the O₃ offset factor.

O₃ offset constant (Address = 0x0108)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x0108
264
f32
2
read/write
0
This register represents the O₃ offset constant.

O₃ sensitivity (Address = 0x010A)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x010A
266
f32
2
read/write
0
This register represents the sensitivity of O₃.

O₃ NO₂ sensitivity (Address = 0x010C)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x010C
268
f32
2
read/write
0
This record shows the sensitivity of the O₃ sensor to NO₂. Since the O₃ sensor is sensitive to both NO₂ and O₃, we need a separate sensitivity value for each gas.

SO₂ (Address = 0x0120)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x0120
288
f32
µg/m³
2
read
NaN
This register contains the SO₂ value retrieved from the most recent poll.

SO₂ 1 hour average (Address = 0x0122)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x0122
290
f32
µg/m³
2
read
NaN
This register contains the 1-hour average SO₂ value.

SO₂ 24 hour average (Address = 0x0124)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x0124
292
f32
µg/m³
2
read
NaN
This register contains the 24-hour average SO₂ value.

SO₂ offset factor (Address = 0x0126)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x0126
294
f32
2
read/write
1
This register represents the SO₂ offset factor.

SO₂ offset constant (Address = 0x0128)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x0128
296
f32
2
read/write
0
This register represents the SO₂ offset constant.

SO₂ sensitivity (Address = 0x012A)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x012A
298
f32
nA/ppm
2
read/write
0
This register represents the sensitivity of SO₂.

NO (Address = 0x01A0)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x01A0
416
f32
µg/m³
2
read
NaN
This register contains the NO value retrieved from the most recent poll.

NO 1 hour average (Address = 0x01A2)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x01A2
418
f32
µg/m³
2
read
NaN
This register contains the 1-hour average NO value.

NO offset factor (Address = 0x01A4)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x01A4
420
f32
2
read/write
1
This register represents the NO offset factor.

NO offset constant (Address = 0x01A6)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x01A6
422
f32
2
read/write
0
This register represents the NO offset constant.

NO sensitivity (Address = 0x01A8)

Address (Hexadecimal)
Address (Decimal)
Type
Unit
# Registers
Access
Default Value
0x01A8
424
f32
nA/ppm
2
read/write
0
This register represents the sensitivity of NO.

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