Michell Easidew EA2 dew-point transmitter (M12 Modbus variant)

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
Instrument Modbus Address	0	U16	1
Humidity Parameter (1 decimal place mode)	1	I16	0.1
Ambient Temperature (1 decimal place mode)	2	I16	0.1
Status/Fault Indication	3	U16	1
Output Configuration	4	U16	1
Ambient Temperature (4 decimal place mode)	7	I16	0.1
Transmitter Firmware Version	8	U16	1
Measurement Range Low	10	I16	0.1
Measurement Range High	11	I16	0.1
Sensor Batch Number	15	U16	1
Sensor Serial Number	16	U16	1
Year of Calibration	17	U16	1
Month & Day of Calibration	18	U16	1
Pressure value for ppmV (barg)	54	I16	0.1
Natural Gas Configuration & Precision Select	78	U16	1

link settings as documented (unverified): RTU; default 9600 8N1; FC 03,06,16; The RS485 interface on the DIN version is intended for configuration and diagnostics and should only be used with a Michell Instruments communications kit. The M12 version of the transmitter should be used if continuous monitoring or measurement via the RS485 / Modbus interface is required.

⚠ Incorrect wiring of the transmitter may result in permanent damage. — Starkest reads only; we never write a control register.

bench facts as documented (unverified)

terminals	M12 5-way A coded connector or MiniDIN 43650 form C
A/B polarity	Modbus A, Modbus B
connector	M12 5-pin (A coded) or MiniDIN 43650 form C
shield/ground	Pin 5 (Grey) / GND (Blue) directly connects to the metal casing of the transmitter, but not to the transmitter electronics, and is intended for cable screening only.
wiring notes	Recommended to use 3-core screened cable.
serial register	16
firmware register	8
identification notes	Sensor Batch Number is at register 15.
power	12...28 V DC, 23 mA max
environment	Operating temperature: -40...+60 °C, Compensated temperature range: -20...+50 °C, Storage temperature: -40...+60 °C, Operating pressure: 45 MPa (450 barg) maximum
accuracy	±2°C dew point
certifications	CE, UKCA, UL approved (UL61010-1 & CAN/CSA C22.2 No. 61010-1), ATEX/UKCA: II 1 G Ex ia IIC T4 Ga (-20...+70 °C), IECEx: EX ia IIC T4 Ga (-20...+70 °C), TR CU@ 0Ex ia IICT4 Ga (-20...+70 °C), cQPSus: Class I, Division 1, Groups A B C D, T4
doc revision	97504 Issue 3.3, March 2022

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

confirmed: comms defaults (9600 baud, RTU, 8N1, FC 3/6/16) — confirmed by the Easidew Dew-Point Transmitter User Manual (97504 Issue 3.3, March 2022, Appendix B)
confirmed: DIN vs M12 RS485 usage note — confirmed by the Easidew Dew-Point Transmitter User Manual (Section 2.2.4)
confirmed: accuracy (±2°C dew point) — confirmed by the Easidew Dew-Point Transmitter User Manual (Appendix A)
confirmed: certifications (CE, UKCA, UL, ATEX, IECEx, TR CU, cQPSus) — confirmed by the Easidew Dew-Point Transmitter User Manual (Appendix A)
confirmed: environmental limits (-40...+60 °C operating, -20...+50 °C compensated, 45 MPa max pressure) — confirmed by the Easidew Dew-Point Transmitter User Manual (Appendix A)
confirmed: power requirements (12...28 V DC, 23 mA max) — confirmed by the Easidew Dew-Point Transmitter User Manual (Appendix A)
confirmed: connector pinout and shield ground behavior (Pin 5 Grey / GND Blue directly connects to metal casing for screening only) — confirmed by the Easidew Dew-Point Transmitter User Manual (Section 2.2.2.1)
confirmed: identification registers (firmware @ 8, batch @ 15, serial @ 16) — confirmed by the Easidew Dew-Point Transmitter User Manual (Appendix B)

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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