Omron FINS Protocol Basics & Benefits of Bridging to MQTT

27th March 2025| 27th March 2025 0 Comments 9 min read

Introduction

Omron’s Factory Interface Network Service (FINS) protocol is a communication protocol used for data exchange between Omron PLCs and other devices. It is widely utilized in industrial automation systems for seamless communication across different Omron devices. However, with the growing need for IIoT (Industrial Internet of Things) connectivity, integrating FINS with modern protocols like MQTT (Message Queuing Telemetry Transport) can provide significant advantages in terms of efficiency, scalability, and remote monitoring capabilities.

In this article, we will explore the fundamentals of Omron FINS, its communication mechanisms, and how bridging FINS to MQTT can enhance industrial automation systems.

Basics of Omron FINS Protocol

What is FINS?

FINS (Factory Interface Network Service) is Omron’s proprietary protocol designed for industrial automation applications. It allows PLCs, HMIs, and other industrial devices to communicate over different networks such as Ethernet, Controller Link, Serial, and DeviceNet.

Communication Layers in FINS

FINS operates over multiple network layers:

Physical Layer: RS-232C, Ethernet, Controller Link, or Host Link
Data Link Layer: Ethernet (TCP/IP or UDP/IP), Controller Link, or Serial Communication
Application Layer: FINS commands and responses

FINS Addressing Structure

Each device on a FINS network has a unique address that consists of:

Network Address: Identifies the network number
Node Address: Identifies the node (device) in the network
Unit Address: Identifies the specific unit within a device (e.g., CPU, expansion module)

A typical FINS command consists of:

Header: Specifies command type, network address, and node information
Command Code: Identifies the operation (e.g., read/write memory, control I/O, etc.)
Data Block: Contains data for processing

FINS Communication Modes

Omron FINS protocol supports three main communication modes:

Explicit Message Communication: Devices send specific requests and receive responses (e.g., reading or writing data).
Cyclic Communication: PLCs exchange data automatically at fixed intervals.
Broadcast Messaging: A message is sent to multiple devices in the network without expecting a response.

Why Bridge FINS to MQTT?

While FINS is a robust protocol for Omron-based automation systems, modern industrial setups require seamless cloud integration and efficient remote monitoring. MQTT, a lightweight publish-subscribe protocol, is an ideal choice for bridging FINS-based industrial automation with IIoT platforms.

Benefits of Bridging FINS to MQTT

Real-Time Data Exchange: MQTT provides low-latency communication, making real-time monitoring of PLCs and sensors more efficient than traditional polling methods in FINS.
Reduced Network Overhead: Unlike FINS, which requires request-response cycles, MQTT operates on a publish-subscribe model, reducing network traffic and improving efficiency.
Cloud Integration: MQTT facilitates direct data transmission to cloud platforms like AWS IoT, Microsoft Azure IoT, and Google Cloud IoT for remote monitoring and analytics.
Enhanced Scalability: MQTT supports a large number of connected devices without performance degradation, making it suitable for large-scale industrial networks.
Security Enhancements: MQTT supports encryption (TLS/SSL) and authentication mechanisms (username/password, certificates), providing better security compared to FINS over TCP/IP.
Cross-Vendor Compatibility: MQTT can integrate data from Omron PLCs and other industrial devices, enabling interoperability in multi-vendor environments.
Event-Driven Communication: MQTT enables devices to send data only when changes occur, optimizing bandwidth usage compared to the continuous polling nature of FINS.

How to Bridge Omron FINS to MQTT

1. Using a Protocol Gateway

A protocol gateway (such as an IIoT Edge Gateway) can act as a bridge between FINS and MQTT. It collects data from Omron PLCs using FINS commands and publishes it to an MQTT broker.

2. Using an Edge Computing Device

Edge computing devices (like Raspberry Pi, industrial PCs) can run software that communicates with Omron PLCs using FINS and forwards data to an MQTT broker. Python libraries such as pyOmronFinsUDP can be used for FINS communication, and paho-mqtt can handle MQTT publishing.

3. Using MQTT-Compatible PLCs

Some Omron PLCs support MQTT natively or through firmware updates. If available, this eliminates the need for an external bridge.

4. Developing a Custom Middleware

A custom software solution (written in Python, Node.js, or C++) can act as middleware between Omron FINS devices and an MQTT broker. The middleware:

Reads data from PLCs using FINS commands
Formats the data for MQTT transmission
Publishes it to the MQTT broker
Subscribes to MQTT topics to send commands back to PLCs

Practical Implementation Example

Hardware Requirements:

Omron PLC (e.g., CJ2M, CP1L, NX1P)
Industrial PC or Raspberry Pi
Network connection (Ethernet/Serial)
MQTT Broker (Mosquitto, EMQX, AWS IoT Core)

Software Setup:

Install Python and required libraries:

pip install paho-mqtt pyOmronFinsUDP

Python script to fetch FINS data and send to MQTT:

Python

import fins.udp
import paho.mqtt.client as mqtt

# Setup FINS connection
fins_instance = fins.udp.UDPFinsConnection()
fins_instance.connect('192.168.1.10')  # Omron PLC IP

# Setup MQTT connection
mqtt_client = mqtt.Client()
mqtt_client.connect("mqtt_broker_ip", 1883)

# Read PLC Data
def read_plc_data():
    fins_instance.dest_node_add = 1  # Set PLC node address
    response = fins_instance.read_memory_area(0x82, 0, 0, 10)  # Read 10 words
    return response

# Publish data to MQTT
while True:
    data = read_plc_data()
    mqtt_client.publish("omron/plc/data", str(data))

This script reads data from an Omron PLC using FINS and publishes it to an MQTT broker.

Conclusion

The Omron FINS protocol remains a reliable solution for industrial automation, but bridging it to MQTT unlocks new possibilities for IIoT integration, remote monitoring, and cloud-based analytics. By leveraging MQTT’s lightweight and scalable architecture, industries can enhance their automation systems, reduce latency, and improve efficiency.

Bridging FINS to MQTT can be achieved using protocol gateways, edge devices, or custom middleware, making it a practical and flexible solution for modern industrial applications.

Omron FINS Protocol Basics & Benefits of Bridging to MQTT

Introduction