Schneider Altivar ATV31/ATV312 drive

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
switching_frequency	3102	U16	0.1	0.1 kHz
maximum_output_frequency	3103	U16	0.1	0.1 Hz
high_speed	3104	U16	0.1	0.1 Hz
low_speed	3105	U16	0.1	0.1 Hz
acceleration	9001	U16	1	s

link settings as documented (unverified): RTU; default 19200 8E1; unit ID 1; FC 03,06,16,43; Modbus format defaults to 8E1. Address range is 1 to 247.

⚠ If Modbus fault management SLL is set to nO, communication control will be inhibited. For safety reasons, inhibition of communication fault should only be used for adjustment or special applications purpose. — Starkest reads only; we never write a control register.

bench facts as documented (unverified)

terminals	RJ45 connector
A/B polarity	Pin 4: D1 Modbus signal, Pin 5: D0 Modbus signal, Pin 8: Common Modbus signal
termination	One 120 Ohm 0.25 W resistor in series with a 1nF 10 V capacitor
connector	RJ45
shield/ground	Connect the cable shielding to the ground of each device.
wiring notes	Type of trunk cable: Shielded cable with 1 twisted pair and at least a third conductor. Maximum length of bus: 1000 m at 19200 bps with Telemecanique TSX CSA••• cable.
max registers/read	29
response timeout	10000 ms
broadcast	supported
protocol notes	Max write registers (FC16): 27 words max. End of frame detected on silence >= 3 characters.
identification notes	Function 43 (16#2B) returns Manufacturer name (Object 1), Device reference (Object 2), and Device version (Object 3).
FC 43 device ID	supported
power	VP (Pin 7) supply for RS232 / RS485 converter or a remote terminal
doc revision	BBV52816 04/2009

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

Incorrect connections on the RJ45 ModBus/CANopen port can cause an InF (Internal Fault) on the Altivar 31 and ATV312 drives, particularly if pin 7 (10VDC supply) is improperly wired or overloaded. [source]
The RJ45 pinout 'view from underneath' diagram in the manual can be confusing, leading to users swapping the RS-485 A (Data-) and B (Data+) lines (polarity surprise). [source]
RS-485 signal polarity (A- and B+ lines) can be swapped depending on the master controller's convention, causing communication timeouts (Error Code 55) when integrating with PLCs like Allen-Bradley Micro850. [source]
confirmed: Baud rates [4800, 9600, 19200] and default 19200 — confirmed by Altivar 312 Modbus manual (BBV52816 04/2009) page 12
confirmed: Modbus format defaults to 8E1, address range 1 to 247 — confirmed by Altivar 312 Modbus manual (BBV52816 04/2009) page 12
confirmed: RJ45 pinout: Pin 4: D1, Pin 5: D0, Pin 8: Common — confirmed by Schneider Electric FAQ 'What is the pin-out of the RJ45 socket of an ATV31 / 312 / 320'
confirmed: Function 43 (16#2B) returns Manufacturer name (Object 1), Device reference (Object 2), and Device version (Object 3) — confirmed by Altivar 312 Modbus manual (BBV52816 04/2009) page 13
confirmed: Max read registers: 29, Max write registers: 27 — confirmed by Altivar 312 Modbus manual (BBV52816 04/2009) page 12
confirmed: Register map: switching_frequency @ 3102, maximum_output_frequency @ 3103, high_speed @ 3104, low_speed @ 3105, acceleration @ 9001 — confirmed by Altivar 312 Modbus manual (BBV52816 04/2009) and Altivar 312 Communication Variables Manual

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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