Onicon System-10 BTU meter (needs MOD interface card)

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
Meter Operating Mode Indicator	0	U16	1
Mode Status Indicator	1	U16	1
Energy Rate – Btu/Hr	2	U16	1	Btu/Hr
Energy Rate – kBtu/Hr	3	U16	1	kBtu/Hr
Energy Rate – MBtu/Hr	4	U16	1	MBtu/Hr
Energy Rate – kW	5	U16	1	kW
Energy Rate – kW x 10	6	U16	1	kW x 10
Energy Rate – Tons	7	U16	1	Tons
Volume Rate – GPM	8	U16	1	GPM
Volume Rate – GPM x 10	9	U16	1	GPM x 10
Volume Rate – GPH	10	U16	1	GPH
Volume Rate – MGD	11	U16	1	MGD
Volume Rate – L/S	12	U16	1	L/S
Volume Rate – L/M	13	U16	1	L/M
Volume Rate – L/Hr	14	U16	1	L/Hr
Volume Rate – M³/Hr	15	U16	1	M³/Hr
Volume Rate – M³/Hr x 10	16	U16	1	M³/Hr x 10
Mass Rate – Lb/Hr	17	U16	1	Lb/Hr
Mass Rate – Lb/Hr x 10	18	U16	1	Lb/Hr x 10
Mass Rate – kg/Hr	19	U16	1	kg/Hr
Mass Rate – kg/Hr x 10	20	U16	1	kg/Hr x 10
Supply Temperature – °F	21	U16	0.01	°F
Return Temperature – °F	22	U16	0.01	°F
Supply Temperature – °C	23	I16	0.01	°C
Return Temperature – °C	24	I16	0.01	°C
Energy Total Mode 1 - kBtu	25	U16	1	kBtu
Energy Total Mode 1 - MBtu	26	U16	1	MBtu
Energy Total Mode 1 – GBtu	27	U16	1	GBtu
Energy Total Mode 2 – kBtu	28	U16	1	kBtu
Energy Total Mode 2 – MBtu	29	U16	1	MBtu
Energy Total Mode 2 – GBtu	30	U16	1	GBtu
Energy Total Mode 1 – TonHr	31	U16	1	TonHr
Energy Total Mode 1 – kTonHr	32	U16	1	kTonHr
Energy Total Mode 2 – TonHr	33	U16	1	TonHr
Energy Total Mode 2 – kTonHr	34	U16	1	kTonHr
Energy Total Mode 1 – kWHr	35	U16	1	kWHr
Energy Total Mode 1 – MWHr	36	U16	1	MWHr
Energy Total Mode 1 – GWHr	37	U16	1	GWHr
Energy Total Mode 2 – kWHr	38	U16	1	kWHr
Energy Total Mode 2 – MWHr	39	U16	1	MWHr
Energy Total Mode 2 – GWHr	40	U16	1	GWHr
Volume Total Mode 1 - kGal	41	U16	1	kGal
Volume Total Mode 1 - MGal	42	U16	1	MGal
Volume Total Mode 1 – GGal	43	U16	1	GGal
Volume Total Mode 2 – kGal	44	U16	1	kGal
Volume Total Mode 2 – MGal	45	U16	1	MGal
Volume Total Mode 2 – GGal	46	U16	1	GGal
Volume Total Mode 1 – kLiters	47	U16	1	kLiters
Volume Total Mode 1 – MLiters	48	U16	1	MLiters
Volume Total Mode 1 – GLiters	49	U16	1	GLiters
Volume Total Mode 2 – kLiters	50	U16	1	kLiters
Volume Total Mode 2 – MLiters	51	U16	1	MLiters
Volume Total Mode 2 – GLiters	52	U16	1	GLiters
Volume Total Mode 1 –M³	53	U16	1	M³
Volume Total Mode 1 – kM³	54	U16	1	kM³
Volume Total Mode 2 –M³	55	U16	1	M³
Volume Total Mode 2 – kM³	56	U16	1	kM³
Mass Total – kLbs	57	U16	1	kLbs
Mass Total – MLbs	58	U16	1	MLbs
Mass Total – Kkgs	59	U16	1	Kkgs
Mass Total – Mkgs	60	U16	1	Mkgs
Auxiliary Input Total (Di3)	61	U16	1
Auxiliary Input Total (x1000)	62	U16	1
Zero Mode 1 Energy Total	63	U16	1
Zero Mode 1 Volume Total	64	U16	1
Zero Mode 2 Energy Total	65	U16	1
Zero Mode 2 Volume Total	66	U16	1
Zero Auxiliary Input Total (Di3)	67	U16	1
Meter Operating Mode Indicator	1000	U16	1
Mode Status Indicator	1001	U16	1
Energy Rate – Btu/Hr	1002	F32BE	1	Btu/Hr
Energy Rate – kW	1004	F32BE	1	kW
Energy Rate – Tons	1006	F32BE	1	Tons
Volume Rate – GPM	1008	F32BE	1	GPM
Volume Rate – GPH	1010	F32BE	1	GPH
Volume Rate – MGD	1012	F32BE	1	MGD
Volume Rate – L/S	1014	F32BE	1	L/S
Volume Rate – L/M	1016	F32BE	1	L/M
Volume Rate – L/H	1018	F32BE	1	L/H
Volume Rate – M³/Hr	1020	F32BE	1	M³/Hr
Mass Rate – Lb/Hr	1022	F32BE	1	Lb/Hr
Mass Rate – Kg/Hr	1024	F32BE	1	Kg/Hr
Supply Temperature – °F	1026	F32BE	1	°F
Return Temperature – °F	1028	F32BE	1	°F
Supply Temperature – °C	1030	F32BE	1	°C
Return Temperature – °C	1032	F32BE	1	°C
Energy Total Mode 1 –Btu	1034	F32BE	1	Btu
Energy Total Mode 2 –Btu	1036	F32BE	1	Btu
Energy Total Mode 1 – TonHr	1038	F32BE	1	TonHr
Energy Total Mode 2 – TonHr	1040	F32BE	1	TonHr
Energy Total Mode 1 – kWHr	1042	F32BE	1	kWHr
Energy Total Mode 2 – kWHr	1044	F32BE	1	kWHr
Volume Total Mode 1 –Gal	1046	F32BE	1	Gal
Volume Total Mode 2 –Gal	1048	F32BE	1	Gal
Volume Total Mode 1 – Liters	1050	F32BE	1	Liters
Volume Total Mode 2 – Liters	1052	F32BE	1	Liters
Volume Total Mode 1 – M³	1054	F32BE	1	M³
Volume Total Mode 2 – M³	1056	F32BE	1	M³
Mass Total –Lbs	1058	F32BE	1	Lbs
Mass Total –kg	1060	F32BE	1	kg
Auxiliary Input Total (Di3)	1062	F32BE	1
Zero Mode 1 Energy Total	1064	U16	1
Zero Mode 1 Volume Total	1065	U16	1
Zero Mode 2 Energy Total	1066	U16	1
Zero Mode 2 Volume Total	1067	U16	1
Zero Auxiliary Input Total (Di3)	1068	U16	1
Volume Rate - Ft³/S	1070	F32BE	1	Ft³/S
Volume Rate - Ft³/M	1072	F32BE	1	Ft³/M
Volume Total Mode 1 – Ft³	1078	F32BE	1	Ft³
Volume Total Mode 2 – Ft³	1080	F32BE	1	Ft³

link settings as documented (unverified): RTU/TCP; default 9600 8N1; unit ID 17; FC 03,06,16,17; RS485 transceiver is 2-wire, half-duplex. TCP/IP transceiver is 10Base T, 10Mbps, RJ45 connection.

bench facts as documented (unverified)

terminals	Terminal T1 for RS485, Terminal T2 for Aux Pulse Input (Di3)
A/B polarity	RS485 network cable connections are polarity sensitive (+ to + and - to -)
termination	Jumper selectable 120 Ohm resistor
connector	RJ45 for TCP/IP, screw terminals for RS485
shield/ground	Incoming and outgoing RS485 cable shield wires should be connected together, but must not be connected to the Btu meter.
protocol notes	Resetting totals requires writing a 1 to a register, which takes longer to accomplish than reading registers and can lead to timeout issues.
power	24 VAC input
doc revision	07-18

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

confirmed: Baud rates [1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200] and default baud 9600 — confirmed by System-10-MOD Network Interface Installation Guide
confirmed: Default unit ID 17 (represented as 017) — confirmed by System-10-MOD Network Interface Installation Guide
confirmed: Framing RTU and TCP, and supported function codes 3, 6, 16, 17 — confirmed by System-10-MOD Network Interface Installation Guide
confirmed: RS485 transceiver is 2-wire half-duplex, and TCP/IP is 10Base T, 10Mbps, RJ45 — confirmed by System-10-MOD Network Interface Installation Guide
confirmed: Parity N and Stop bits 1 — confirmed by System-10-MOD Network Interface Installation Guide
confirmed: Shield ground wires must be connected together but not to the Btu meter — confirmed by System-10-MOD Network Interface Installation Guide
confirmed: Terminal T1 for RS485 and Terminal T2 for Aux Pulse Input (Di3) — confirmed by System-10-MOD Network Interface Installation Guide
confirmed: Jumper selectable 120 Ohm termination resistor — confirmed by System-10-MOD Network Interface Installation Guide

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.

Device not here? Upload its manual and get a checked map back. It's free.

Want it confirmed against your own device? Order hardware verification. If it doesn't check out, you don't pay.

Building on a lot of devices? License the library — machine-readable maps, the firmware matrix, and API access.