VPInstruments VPFlowScope In-line flow meter

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.

structure-verified

Decode path is structurally sound (addresses, widths, finite values). Does NOT prove word order or scaling.

point	address (0-based)	type	scale	unit
Diameter	8	F32LE	1
4 .. 20 mA Max	9	F32LE	1
4 .. 20 mA Min	10	F32LE	1
4 .. 20 mA Unit	11	F32LE	1
Flow in mn/sec	16	I32LE	0.1	mn/sec
Flow in m3n/hr	17	I32LE	0.1	m3n/hr
Flow in ln/min	18	I32LE	0.1	ln/min
Flow in SCFM	19	I32LE	0.1	SCFM
Flow in m3n/min	20	I32LE	0.1	m3n/min
Flow in sfps	21	I32LE	0.1	sfps
Flow in mn/sec	24	F32LE	1	mn/sec
Flow in m3n/hr	25	F32LE	1	m3n/hr
Flow in ln/min	26	F32LE	1	ln/min
Flow in SCFM	27	F32LE	1	SCFM
Flow in m3n/min	28	F32LE	1	m3n/min
Flow in sfps	29	F32LE	1	sfps
Pressure in bar	32	I32LE	0.1	bar
Pressure in psi	33	I32LE	0.1	psi
Pressure in bar	40	F32LE	1	bar
Pressure in psi	41	F32LE	1	psi
Temperature in °C	64	I32LE	0.1	°C
Temperature in °F	65	I32LE	0.1	°F
Temperature in °C	72	F32LE	1	°C
Temperature in °F	73	F32LE	1	°F
Totalizer in m3n	128	I32LE	0.1	m3n
Totalizer in m3n	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.
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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