How do I connect modbus-serial to a serial port on Windows?

Use the connectRTUBuffered method with the correct COM port, e.g., 'COM3', and ensure the serialport dependency is installed. If installation fails, try using --unsafe-perm or install serialport separately, as noted in the README's install options.

modbus-serial or node-modbus: which is better for industrial projects?

modbus-serial is a pure JavaScript library with broader protocol support and easier TCP/UDP deployment, while node-modbus might offer better performance with native bindings for serial. Choose modbus-serial for flexibility and Node.js integration, but consider node-modbus for high-throughput serial needs.

Why does modbus-serial fail when I try to use serial functions?

This usually happens if the optional serialport dependency isn't installed. Install it explicitly with npm install serialport, or check that it wasn't skipped during installation using --no-optional, as explained in the README's dependency section.

How can I create a MODBUS TCP server with modbus-serial?

Use the ServerTCP class by providing a vector object with callback functions for handling requests, as shown in the examples. Set up the server with host and port options, and handle events like socketError for robustness.

Does modbus-serial support reading from multiple slaves efficiently?

Yes, it supports polling multiple slaves with async/await and timeouts, as demonstrated in the 'Read on multiple slaves' example. Use setID to switch between devices and implement error handling to manage unresponsive units.

What are the Node.js version requirements for modbus-serial with serial support?

For serial support, Node.js 20 or newer is recommended due to the serialport 13.x dependency. TCP/UDP usage works on older versions, but serial functionality may require downgrading serialport or using specific install flags.

modbus-serial — JavaScript MODBUS-RTU for Node.js

What is modbus-serial?

modbus-serial is a Node.js library that implements the MODBUS-RTU and MODBUS-TCP protocols in pure JavaScript. It allows developers to communicate with industrial electronic devices, such as PLCs, irrigation controllers, and robots, over serial lines (e.g., RS485, RS232) or TCP/IP networks. The library supports standard MODBUS function codes for reading and writing data to devices, making it a versatile tool for industrial automation and IoT projects.

Target Audience

Developers and engineers working on industrial automation, IoT, or robotics projects that require communication with MODBUS-enabled devices. It is particularly useful for Node.js developers integrating with PLCs, Arduino-based systems, or other industrial equipment.

Value Proposition

Developers choose modbus-serial because it is a pure JavaScript implementation with no native dependencies for TCP/UDP usage, making it easy to install and deploy. It supports multiple transport protocols (serial, TCP, UDP, Telnet) and includes both client and server modes, offering flexibility for various industrial communication scenarios.

A pure JavaScript implemetation of MODBUS-RTU (and TCP) for NodeJS

Use Cases

Best For

Communicating with industrial PLCs and controllers over serial RS485/RS232
Building IoT gateways that bridge MODBUS devices to Node.js applications
Creating MODBUS-TCP servers for simulating or testing industrial equipment
Integrating Arduino-based MODBUS slaves into Node.js automation systems
Logging data from multiple MODBUS slaves (e.g., meters, sensors) in real-time
Developing irrigation control systems or robotics with MODBUS protocol support

Not Ideal For

Projects requiring high-speed, real-time MODBUS communication with minimal latency, as the pure JavaScript implementation may introduce performance overhead.
Systems constrained to older Node.js versions (below 20) that need serial support, due to dependency conflicts with serialport 13.x.
Applications needing robust MODBUS server functionality over serial lines, as server support is primarily focused on TCP with limited serial server options.
Developers who prefer batteries-included libraries with no optional dependencies, as serialport setup can be cumbersome and error-prone.

Pros & Cons

Pros

Pure JavaScript Core

Implements MODBUS protocols without native dependencies for TCP/UDP, enabling easier deployment in environments where serial hardware isn't needed, as highlighted by the optional serialport dependency.

Comprehensive Protocol Support

Supports MODBUS-RTU, MODBUS-TCP, UDP, Telnet, and ASCII, covering a wide range of industrial communication scenarios, as evidenced by the multiple port classes and examples in the README.

Client and Server Modes

Includes both client classes for querying devices and a ServerTCP class for creating MODBUS-TCP servers, offering flexibility for testing and simulation, with detailed vector-based examples provided.

Full Function Code Implementation

Implements standard MODBUS function codes (FC1-FC16, FC22, FC43/14), allowing complete read/write operations on coils, registers, and device identification, as listed in the compatibility table.

Cons

Serial Dependency Complexity

The optional serialport dependency can cause installation headaches, requiring specific npm flags or manual installation, and serial-specific APIs fail at runtime if not properly set up, as warned in the README.

Limited Serial Server Support

Server functionality is primarily for TCP; serial server support is less documented or might be incomplete, limiting its use for serial-based master devices compared to the robust TCP server examples.

Performance Overhead

As a pure JavaScript library, it may not match the performance of native C++ bindings for high-frequency data polling or latency-sensitive applications, which could be a bottleneck in industrial automation.

Frequently Asked Questions

What is modbus-serial?

Target Audience

Value Proposition

Use Cases

Best For

Communicating with industrial PLCs and controllers over serial RS485/RS232
Building IoT gateways that bridge MODBUS devices to Node.js applications
Creating MODBUS-TCP servers for simulating or testing industrial equipment
Integrating Arduino-based MODBUS slaves into Node.js automation systems
Logging data from multiple MODBUS slaves (e.g., meters, sensors) in real-time
Developing irrigation control systems or robotics with MODBUS protocol support

Not Ideal For

Projects requiring high-speed, real-time MODBUS communication with minimal latency, as the pure JavaScript implementation may introduce performance overhead.
Systems constrained to older Node.js versions (below 20) that need serial support, due to dependency conflicts with serialport 13.x.
Applications needing robust MODBUS server functionality over serial lines, as server support is primarily focused on TCP with limited serial server options.
Developers who prefer batteries-included libraries with no optional dependencies, as serialport setup can be cumbersome and error-prone.

Pros & Cons

Pros

Pure JavaScript Core

Comprehensive Protocol Support

Supports MODBUS-RTU, MODBUS-TCP, UDP, Telnet, and ASCII, covering a wide range of industrial communication scenarios, as evidenced by the multiple port classes and examples in the README.

Client and Server Modes

Includes both client classes for querying devices and a ServerTCP class for creating MODBUS-TCP servers, offering flexibility for testing and simulation, with detailed vector-based examples provided.

Full Function Code Implementation

Implements standard MODBUS function codes (FC1-FC16, FC22, FC43/14), allowing complete read/write operations on coils, registers, and device identification, as listed in the compatibility table.

Cons

Serial Dependency Complexity

Limited Serial Server Support

Performance Overhead

Frequently Asked Questions

modbus-serial

What is modbus-serial?

Overview

Use Cases

Best For

Not Ideal For

Pros & Cons

Pros

Cons

Frequently Asked Questions

Related Projects

Found a gem we're missing?

modbus-serial

What is modbus-serial?

Overview

Use Cases

Best For

Not Ideal For

Pros & Cons

Pros

Cons

Frequently Asked Questions

Related Projects

Found a gem we're missing?