AERCO BMS/C-More boiler controller

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
default_message_display_code	0	U16	1
unit_status	1	U16	1
outlet_temp	2	U16	1	DEGREES_1
inlet_temp	3	U16	1	DEGREES_1
aux_temp	4	U16	1	DEGREES_1
outdoor_temp	5	U16	1	DEGREES_2
exhaust_temp	6	U16	1	DEGREES_2
ffwd_temp	7	U16	1	DEGREES_1
fire_rate_out	8	U16	1	%
o2_level	9	U16	1	%
co_level	10	U16	1	PPM
run_cycles_low	11	U16	1
run_cycles_high	12	U16	1
run_hours_low	13	U16	1
run_hours_high	14	U16	1
flame_strength	15	U16	1	%
active_setpoint	16	U16	1	DEGREES_1
fire_rate_in	17	U16	1	%
manual_fire_rate	18	U16	1	%

link settings as documented (unverified): RTU; default 9600 8??; unit ID 128; FC 03,04,06,08,17; RTU transmission ONLY. C-More baud rate is fixed at 9600.

bench facts as documented (unverified)

terminals	RS485, 2-Wire Differential Bus With Shield
A/B polarity	It is imperative that polarity be maintained between all Modbus Network connections.
termination	A terminating resistor (120 ohms) on each end of the RS485 loop. BMS/BMS II has a built-in 120 ohm terminating resistor.
connector	RS232 (DB9-Female) and internal RS232 connector
isolation	232 ISO GND
shield/ground	twisted-pair wiring shield should only be terminated at the controlling Master Controller for the Modbus Network.
broadcast	supported
protocol notes	Heartbeat Timeout: Fixed at 10 seconds For C-More, Adjustable For BMS/BMS II: 5 to 240 Seconds
firmware register	20
FC 43 device ID	not supported
power	85-265 VAC
doc revision	REVISED FEBRUARY 17, 2011

generated by gemini:gemini-3.5-flash · harvested from https://www.ccontrols.com/support/dp/AercoCMore.pdf (AERCO); 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.