This document is the Modbus User's manual for Altivar 31 variable speed drives from Schneider Electric SA. It provides information on the connection to RS485 bus, Modbus protocol, and non-standard RS485 schematics in the appendix.
The Altivar 31 Modbus User Manual provides installation instructions, wiring diagrams and configuration details for connecting the Altivar 31 drive to an RS485 network. It describes the physical layer, cable requirements, termination and polarisation, as well as the Modbus protocol used for communication.
The document also includes an appendix with non‑standard RS485 schematics, mixed and J‑bus configurations, and recommendations for setting up a reliable Modbus network with the Altivar 31.
| Maximum bus length | 1000 m at 19200 bps |
|---|---|
| Maximum number of stations (without repeater) | 32 stations (31 slaves) |
| Maximum tap link length (single tap) | 20 m |
The RS485 bus can be up to 1000 m long when operating at 19200 bps.
Up to 32 stations (31 slaves) can be connected on the bus without a repeater.
A 120 Ω resistor in series with a 1 nF, 10 V capacitor is recommended for line termination.