Crowcon Gasmaster III gas panel

Register map(s) for this device, each at the trust rung it earned. Addresses are 0-based as on the wire; word order and scaling are only confirmed at the hardware-verified rung.

interop-verified

Read + decoded cleanly over a real network vs an independent third-party Modbus test server (transport and framing; reads are remapped into the server's register window, so the map's own addresses are NOT exercised). Does NOT prove word order/scaling against the actual device.

point	address (0-based)	type	scale	unit
time	500	U32BE	1
status	501	U16	1
system_fault_1	502	U32BE	1
system_fault_2	503	U32BE	1
system_warning_1	504	U32BE	1
system_warning_2	505	U32BE	1
channel_1_level	506	F32BE	1
channel_1_status	507	U16	1
channel_2_level	508	F32BE	1
channel_2_status	509	U16	1
channel_3_level	510	F32BE	1
channel_3_status	511	U16	1
channel_4_level	512	F32BE	1
channel_4_status	513	U16	1
raw_adc_ch1	622	U16	1	mA
raw_adc_ch2	623	U16	1	mA
raw_adc_ch3	624	U16	1	mA
raw_adc_ch4	625	U16	1	V
raw_adc_psu	626	U16	1	V
raw_adc_vsys	627	U16	1	V
raw_adc_p12v	628	U16	1	V
raw_adc_check_low	629	U16	1	V
raw_adc_check_high	630	U16	1	V
raw_adc_vlcd0	631	U16	1	V
raw_adc_vlcd1	632	U16	1

link settings as documented (unverified): RTU; default 9600 8N1; unit ID 1; FC 03,16; A silent interval of 5.7mS is used to define the termination of a data packet. On receipt of a message requiring a response, the instrument will pause for a guaranteed period of at least 50mS before transmission will commence.

bench facts as documented (unverified)

inter-frame delay	5 ms
broadcast	supported
protocol notes	On receipt of a message requiring a response, the instrument will pause for a guaranteed period of at least 50mS before transmission will commence.
model register	1
serial register	4
firmware register	3
identification notes	Manufacturer is at address 2.
FC 43 device ID	not supported
doc revision	FGM3-002 Issue 2 January 2015

generated by gemini:gemini-3.5-flash · harvested from https://www.crowcon.com/wp-content/uploads/2024/09/FGM3-002-Gasmaster-III-Modbus-Instructions-Issue-2-Jan-15.pdf (Crowcon); manual-faithful — the document's claims, panel risk: ELEVATED — panel is not confident; proved interop-verified on 2026-06-10 · recorded 2026-06-10

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.
interop-verified — Read + decoded cleanly over a real network vs an independent third-party Modbus test server (transport and framing; reads are remapped into the server's register window, so the map's own addresses are NOT exercised). Does NOT prove word order/scaling against the actual device.
simulator-verified — Decoded correctly against a protocol emulator seeded with known-true values — catches word-order/scaling errors vs the emulator, not the physical device.
hardware-verified x1 — Matched a real device with operator-attested readings as ground truth — the only rung that confirms word order + scaling on the wire.

Have a device that isn't here? Upload its register map — generation is free, and the connector earns its rung by being proven, not claimed.

Need it proven on your own device? Hardware verification — if it doesn't verify, you don't pay.

Building a platform? License the verified library — machine-readable maps, firmware matrix, API access.