VPInstruments VPFlowScope In-line flow meter

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 confirmed at the hardware-verified rung and at no rung below it.

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
flow_m_n_sec_int	16	U32LE	0.1	mn/sec
flow_m3_n_hr_int	17	U32LE	0.1	m3n/hr
flow_l_n_min_int	18	U32LE	0.1	ln/min
flow_scfm_int	19	U32LE	0.1	SCFM
flow_m3_n_min_int	20	U32LE	0.1	m3n/min
flow_sfps_int	21	U32LE	0.1	sfps
pressure_bar_int	32	U32LE	0.1	bar
pressure_psi_int	33	U32LE	0.1	psi
temperature_c_int	64	U32LE	0.1	°C
temperature_f_int	65	U32LE	0.1	°F
totalizer_m3_n_int	128	U32LE	0.1	m3n
diameter	8	F32LE	1
analog_out_max	9	F32LE	1
analog_out_min	10	F32LE	1
analog_out_unit	11	F32LE	1
flow_m_n_sec_float	24	F32LE	1	mn/sec
flow_m3_n_hr_float	25	F32LE	1	m3n/hr
flow_l_n_min_float	26	F32LE	1	ln/min
flow_scfm_float	27	F32LE	1	SCFM
flow_m3_n_min_float	28	F32LE	1	m3n/min
flow_sfps_float	29	F32LE	1	sfps
pressure_bar_float	40	F32LE	1	bar
pressure_psi_float	41	F32LE	1	psi
temperature_c_float	72	F32LE	1	°C
temperature_f_float	73	F32LE	1	°F
totalizer_m3_n_float	136	F32LE	1	m3n

link settings as documented (unverified): RTU; default 38400 8N1; unit ID 9; FC 03,16; Maximum polling interval is 10ms. Data is refreshed every second.

⚠ NEVER USE AC POWER. THIS WILL VOID WARRANTY AND BRING PERMANENT DAMAGE TO THE ELECTRONICS. CONNECT THE M12 CONNECTOR BEFORE POWERING UP THE INSTRUMENTS. — Starkest reads only; we never write a control register.

bench facts as documented (unverified)

terminals	M12 5-pin female connector
A/B polarity	Pin 4 RS485 B, Pin 5 RS485 A
termination	The VPInstruments junction box features a jumper that can be used to enable a 120 Ohm resistor.
connector	M12 5-pin female connector or M12 8-pin connector
shield/ground	Shielded twisted pair cabling must be used. Connect shield to safety ground on one point.
wiring notes	Connection of a third wire between the master and slave should be done to limit the common mode voltage.
protocol notes	Maximum polling interval is 10ms.
power	12 .. 24 VDC +-10% CLASS 2 (UL), 150 mA at 24 VDC
environment	Ambient temperature 0 .. 60 °C / 32 .. 140 °F, IP65 when mated to connector
accuracy	0.5% FSS under calibration conditions with tubing kit, 5% FSS without tubing kit
certifications	CE EN 61326-1(2006) Class A, EN 61000-6-1 (2007), UL / CUL 14 AZ, Industrial Control Equipment
doc revision	MAN-VP-SINL-EN-2300 Last Revision Date: 21-7-2023

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

RS485 Polarity Swap: Older manuals (e.g., 2015) labeled Pin 4 as RS485 A and Pin 5 as RS485 B, whereas newer manuals (e.g., 2023) label Pin 4 as RS485 B and Pin 5 as RS485 A. This discrepancy can cause polarity issues in the field, requiring users to swap the A and B lines to establish communication. [source]
Consecutive 32-bit Registers: The 32-bit registers (both float and integer) are mapped to consecutive Modbus addresses (e.g., 16, 17, 18...). Because of this, standard contiguous block reads of multiple parameters will result in overlapping or invalid data. Each parameter must be read individually with a length of 2 registers. [source]
confirmed: Baud rates [9600, 19200, 38400], default baud 38400, default unit ID 9, framing RTU, parity N, stop bits 1 — confirmed by VPFlowScope In-line User Manual (MAN-VP-SINL-EN-2300)
confirmed: Accuracy 0.5% FSS under calibration conditions with tubing kit, 5% FSS without tubing kit — confirmed by VPFlowScope In-line User Manual (MAN-VP-SINL-EN-2300)
confirmed: Warning NEVER USE AC POWER... CONNECT THE M12 CONNECTOR BEFORE POWERING UP — confirmed by VPFlowScope In-line User Manual (MAN-VP-SINL-EN-2300)
confirmed: The VPInstruments junction box features a jumper that can be used to enable a 120 Ohm resistor — confirmed by Modbus Junction Box Manual (MAN-VP-AMJB-EN-2500)
confirmed: Register addresses (e.g., flow_m_n_sec_int @ 16, flow_m3_n_hr_int @ 17, flow_l_n_min_int @ 18, flow_scfm_int @ 19, flow_m3_n_min_int @ 20, flow_sfps_int @ 21, pressure_bar_int @ 32, pressure_psi_int @ 33, temperature_c_int @ 64, temperature_f_int @ 65, totalizer_m3_n_int @ 128, diameter @ 8, analog_out_max @ 9, analog_out_min @ 10, analog_out_unit @ 11, flow_m_n_sec_float @ 24, flow_m3_n_hr_float @ 25, flow_l_n_min_float @ 26, flow_scfm_float @ 27, flow_m3_n_min_float @ 28, flow_sfps_float @ 29, pressure_bar_float @ 40, pressure_psi_float @ 41, temperature_c_float @ 72, temperature_f_float @ 73, totalizer_m3_n_float @ 136) — confirmed by VPFlowScope In-line User Manual (MAN-VP-SINL-EN-2300)

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.

If your device isn't here, upload its register map. Generation is free, and the connector keeps the rung it earns under testing.

To prove a connector against your own device, order hardware verification. If it doesn't verify, you don't pay.

Platform builders can license the verified library: machine-readable maps, the firmware matrix, API access.