GE Multilin PQM/PQMII power quality 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
phase_a_current	576	U16	1
phase_b_current	577	U16	1
phase_c_current	578	U16	1
average_current	579	U16	1
neutral_current	580	U16	1
current_unbalance	581	U16	0.1
voltage_van	640	U32BE	1
voltage_vbn	642	U32BE	1
voltage_vcn	644	U32BE	1
average_phase_voltage	646	U32BE	1
voltage_vab	648	U32BE	1
voltage_vbc	650	U32BE	1
voltage_vca	652	U32BE	1
average_line_voltage	654	U32BE	1
voltage_unbalance	656	U16	0.1
three_phase_real_power	752	U32BE	0.01
three_phase_reactive_power	754	U32BE	0.01
three_phase_apparent_power	756	U32BE	0.01
three_phase_power_factor	758	I16	0.01
phase_a_real_power	759	U32BE	0.01
phase_a_reactive_power	761	U32BE	0.01
phase_a_apparent_power	763	U32BE	0.01
phase_a_power_factor	765	I16	0.01
phase_b_real_power	766	U32BE	0.01
phase_b_reactive_power	768	U32BE	0.01
phase_b_apparent_power	770	U32BE	0.01
phase_b_power_factor	772	I16	0.01
phase_c_real_power	773	U32BE	0.01
phase_c_reactive_power	775	U32BE	0.01
phase_c_apparent_power	777	U32BE	0.01
phase_c_power_factor	779	I16	0.01
frequency	1088	U16	0.01
three_phase_positive_real_energy	976	U32BE	1	kWh
three_phase_negative_real_energy	978	U32BE	1	kWh
three_phase_positive_reactive_energy	980	U32BE	1	kvarh
three_phase_negative_reactive_energy	982	U32BE	1	kvarh
three_phase_apparent_energy	984	U32BE	1	kVAh
phase_a_current_demand	1024	U16	1
phase_b_current_demand	1025	U16	1
phase_c_current_demand	1026	U16	1
neutral_current_demand	1027	U16	1
three_phase_real_power_demand	1028	U32BE	0.01
three_phase_reactive_power_demand	1030	U32BE	0.01
three_phase_apparent_power_demand	1032	U32BE	0.01

link settings as documented (unverified): RTU; default 9600 8N1; unit ID 1; FC 03,04,05,06,07,08,16; Up to 32 slaves can be daisy-chained on a single communication channel.

bench facts as documented (unverified)

terminals	each '+' terminal of every device must be connected together
A/B polarity	Polarity is important in RS485 communications
termination	terminating network installed at each end of the link... 120 ohm resistor in series with a 1 nF ceramic capacitor when used with Belden 9841 RS485 wire
connector	2-wire RS485 and 9-pin RS232 interfaces
shield/ground	Shielded wire should always be used to minimize noise.
max registers/read	125
broadcast	supported
protocol notes	Modbus allows up to a maximum of 60 holding registers to be stored in one transmission.
model register	0000
serial register	0020
firmware register	0002
FC 43 device ID	not supported
doc revision	2.2x
firmware applicability	2.2x

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

When reading 32-bit unsigned long integers (such as energy registers) via Modbus, SCADA systems like Citect may require manual word-swapping or custom data type configuration because the PQMII stores 32-bit values across two consecutive 16-bit registers (high-order register first, then low-order register). [source]
confirmed: Baud rates [1200, 2400, 4800, 9600, 19200] with default 9600, parity N, stop bits 1, framing RTU, and default unit ID 1 — confirmed by GE Multilin PQMII Communications Guide (Section 1.3 & Memory Map)
confirmed: Supported Modbus function codes [3, 4, 5, 6, 7, 8, 16] — confirmed by GE Multilin PQMII Communications Guide (Section 2.1)
confirmed: Up to 32 slaves can be daisy-chained on a single communication channel — confirmed by GE Multilin PQMII Communications Guide (Section 1.1)
confirmed: Physical interface uses 2-wire RS485 and 9-pin RS232 — confirmed by GE Multilin PQMII Communications Guide (Section 1.2)
confirmed: Polarity is important in RS485 communications: each '+' terminal of every device must be connected together — confirmed by GE Multilin PQMII Communications Guide (Section 1.2)
confirmed: Shielded wire should always be used to minimize noise — confirmed by GE Multilin PQMII Communications Guide (Section 1.2)
confirmed: Terminating network of 120 ohm resistor in series with a 1 nF ceramic capacitor at each end of the link — confirmed by GE Multilin PQMII Communications Guide (Section 1.2)
confirmed: Broadcast supported via Function Code 05h — confirmed by GE Multilin PQMII Communications Guide (Section 2.4)

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.