E+E EE872 CO2 probe

Register map(s) for this device, with a note of how far each has been checked. Addresses are 0-based, as on the wire. Scale and byte order are confirmed only at the hardware-verified rung.

coherence-checked

Round-trips through a real Modbus stack with no overlapping addresses and a word-order-sensitive codec — the map is internally coherent and wire-decodable. Does NOT prove byte-order or scaling match a real device: the emulator is seeded from the map's own types, so a uniformly wrong byte-order still round-trips. Only hardware-verified confirms byte-order/scale on the wire.

point	address (0-based)	type	scale	unit
Modbus address	0	I16	1
Modbus protocol settings	1	I16	1
Firmware version	8	I16	1
Sensor name (as ASCII)	9	U16	1
Temperature	1002	F32LE	1	°C
Temperature	1004	F32LE	1	°F
Temperature	1008	F32LE	1	K
Relative humidity	1020	F32LE	1	%
CO2 (average)	1060	F32LE	1	ppm
CO2 (raw)	1062	F32LE	1	ppm
Dew point temperature	1104	F32LE	1	°C
Dew point temperature	1106	F32LE	1	°F
Dew point temperature	1146	F32LE	1	K
Pressure	1200	F32LE	1	mbar
Pressure	1202	F32LE	1	psi
Temperature	4001	I16	0.01	°C
Temperature	4002	I16	0.02	°F
Temperature	4004	I16	0.02	K
Relative humidity	4010	I16	0.01	%
CO2 (average)	4030	I16	1	ppm
CO2 (raw)	4031	I16	1	ppm
Dew point temperature	4052	I16	0.01	°C
Dew point temperature	4053	I16	0.01	°F
Dew point temperature	4073	I16	0.01	K
Pressure	4100	I16	0.1	mbar
Pressure	4101	I16	0.01	psi

link settings as documented (unverified): RTU; baud 9600/19200/38400; unit ID 237; FC 03,04,06; The recommended settings for multiple devices in a Modbus RTU network are 9600, 8, even, 1. The EE872 represents 1/10 unit load on an RS485 network.

bench facts as documented (unverified)

connector	M12x1 5 poles
wiring notes	Pin 1: Supply voltage, Pin 2: B RS485 (D-), Pin 3: GND, Pin 4: A RS485 (D+), Pin 5: Configuration pin
protocol notes	When reading information that spans multiple registers, it is always necessary to read all registers, even if the desired information requires less. To obtain the correct floating point values, both registers have to be read within the same reading cycle.
model register	0x09
serial register	0x00
firmware register	0x08
identification notes	Sensor name (as ASCII) is at 0x09 (size 8), Serial number (as ASCII) is at 0x00 (size 8), Firmware version is at 0x08 (size 1)
power	15 - 35 V DC (Current output) or 12 - 30 V DC (RS485 interface and voltage output), max. voltage 30 V DC for USA & Canada Class 2
environment	Storage conditions: -40...+60 °C, 700...1100 mbar, 0...95 %RH, non-condensing. Protection rating: IP65 probe body
accuracy	CO2: <±(40 ppm + 1.8 % of mv) for 0...2000 ppm. RH: ±3 %RH (20...80 %RH). Temp: ±0.5 °C (5...60 °C)
certifications	CE, UKCA, FCC Part 15 Class A, ICES-003 Class A
doc revision	Version v1.6 \| 05-2026

field reports — community-sourced, unverified (checked 2026-06-11)

When reading ASCII-encoded information (such as the serial number spanning registers 0x00 to 0x07), attempting to read a partial block or individual registers instead of the full block results in a Modbus Exception Code 2 (Illegal Data Address). [source]
confirmed: Baud rates [9600, 19200, 38400], default unit ID 237, and Even parity with 1 stop bit — confirmed by E+E EE872 Quick Guide and User Manual
confirmed: M12 5-pin connector pinout (Pin 1: Supply, Pin 2: B RS485, Pin 3: GND, Pin 4: A RS485, Pin 5: Config) — confirmed by E+E EE872 Quick Guide
confirmed: Accuracy specifications (CO2: <±(40 ppm + 1.8 % of mv) for 0...2000 ppm, RH: ±3 %RH, Temp: ±0.5 °C) — confirmed by E+E EE872 Datasheet
confirmed: Register addresses (e.g., co2_average @ 1060, relative_humidity @ 1020, temperature_c @ 1002, and INT16 equivalents like co2_average_int @ 4030) — confirmed by E+E EE872 User Manual register map (where 1-based register numbers 1061, 1021, 1003, and 4031 correspond to 0-based decimal addresses 1060, 1020, 1002, and 4030)

The trust ladder

Each rung states what it proved and what it did not. Gray until proven; green is earned by hardware only.

generated — A prompt produced it. Unproven — anyone can regenerate this.
structure-verified — Decode path is structurally sound (addresses, widths, finite values). Does NOT prove word order or scaling.
coherence-checked — Round-trips through a real Modbus stack with no overlapping addresses and a word-order-sensitive codec — the map is internally coherent and wire-decodable. Does NOT prove byte-order or scaling match a real device: the emulator is seeded from the map's own types, so a uniformly wrong byte-order still round-trips. Only hardware-verified confirms byte-order/scale on the wire.
hardware-verified (software-key) x1 — Matched a real device with operator-attested readings as ground truth — the only rung that confirms word order + scaling on the wire.

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