Commercial library by Step Function I/O

Rust async/await implementation of the Modbus protocol using Tokio with idiomatic bindings for C/C++, Java, and .NET Core.

The library supports Modbus TCP, RTU, and TLS including role-based access control using the X.509 role identifier in the Modbus security specification.

Refer to License.txt for the terms of the non-commercial license. This software is "source available", but is not "open source". You must purchase a commercial license to use this software for profit.

The client and server examples demonstrate simple usage of the API.

The following function codes are supported:

• Read Coils (0x01)
• Read Discrete Inputs (0x02)
• Read Holding Registers (0x03)
• Read Input Registers (0x04)
• Write Single Coil (0x05)
• Write Single Register (0x06)
• Write Multiple Coils (0x0F)
• Write Multiple Registers (0x10)

The library uses the Tokio executor under the hood. The perf example is a benchmark that creates multiple sessions on a single server and sends multiple requests in parallel. On a decent workstation, the benchmark achieved around 200k requests per second spread across 100 concurrent sessions in only 800 KB of memory.

Bindings in C, C++, .NET Core, and Java are available for this library. See the documentation for more details.

You can test Modbus servers from the command line with the rodbus-client crate.