Madbus TCP Client

A simple Rust CLI client for communicating with a Modbus TCP server (slave) using the madbus library.
The program allows reading and writing coils, discrete inputs, holding registers, and input registers via terminal commands.

---

Features

• Connects to a Modbus TCP server
• Supports standard Modbus operations:
  • Read Coils
  • Read Discrete Inputs
  • Read Holding Registers
  • Read Input Registers
  • Write Single / Multiple Coils
  • Write Single / Multiple Holding Registers
• Command-line interface built with clap
• Prints formatted responses from the server
• Handles Modbus exception codes

---

Requirements

• Rust (recommended via rustup)
• Cargo
• Access to a Modbus TCP server

---

Installation

Clone the project and build it:

git clone https://github.com/RipInPease/madbus-cli.git
cd madbus
cargo build --release

The binary will be located at:

target/release/madbus

---

Usage

madbus --ip <IP> [--port <PORT>] [--unit-id <ID>] <COMMAND>

Defaults:

• port: 502
• unit-id: 1

Example:

madbus --ip 192.168.1.10 read-coil 0 5

---

Command Overview

Read Coils

Reads one or more coil states.

madbus --ip <IP> read-coil <start> [count]

Example:

madbus --ip 192.168.1.10 read-coil 0 8

---

Read Discrete Inputs

madbus --ip <IP> read-di <start> [count]

Example:

madbus --ip 192.168.1.10 read-di 0 4

---

Read Holding Registers

madbus --ip <IP> read-holding <start> [count]

Example:

madbus --ip 192.168.1.10 read-holding 0 3

---

Read Input Registers

madbus --ip <IP> read-input <start> [count]

Example:

madbus --ip 192.168.1.10 read-input 0 2

---

Write Coil

Write one or more coils.

madbus --ip <IP> write-coil <start> <value...>

Example:

madbus --ip 192.168.1.10 write-coil 0 true

Write multiple:

madbus --ip 192.168.1.10 write-coil 0 true false true

---

Write Holding Registers

madbus --ip <IP> write-holding <start> <value...>

Example:

madbus --ip 192.168.1.10 write-holding 0 10

Multiple registers:

madbus --ip 192.168.1.10 write-holding 0 10 20 30

---

Output Example

Holding reg values from unit 1:
    40000: 12
    40001: 15
    40002: 42

---

Error Handling

The client handles Modbus exception responses including:

• IllegalCode
• IllegalAddress
• IllegalDataValue
• ServerFailure
• ServerBusy
• GatewayUnavail
• BadDevice
• IOError
• Invalid or malformed Modbus responses

---

Project Structure

src/
 ├── main.rs      # Client logic and response handling
 └── input.rs     # CLI argument definitions

---

Example Full Command

cargo run -- \
  --ip 127.0.0.1 \
  --port 502 \
  --unit-id 1 \
  read-holding 0 5

---

License

MIT