Schneider Altivar ATV31/ATV312 drive
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 |
|---|
| 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.
- 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.