As Industrial IoT (IIoT) adoption grows, companies are seeking reliable ways to send PLC data to the cloud for real-time insights, predictive maintenance, and remote access. Whether you’re modernizing an existing factory or building a new smart system, knowing how to send data from PLC to cloud is essential.
This guide walks you through the methods, protocols, and security measures needed to connect your PLCs to cloud platforms like AWS, Azure, and Google Cloud—without compromising data integrity.
Why Send PLC Data to the Cloud?
Cloud connectivity allows manufacturers to go beyond basic automation. Key benefits include:
- Remote Monitoring: Access machine and sensor data from anywhere.
- Predictive Maintenance: Use analytics and machine learning to reduce downtime.
- Scalability: Easily scale data storage, processing, and dashboards without local server upgrades.
Whether you’re tracking energy usage or analyzing machine performance, moving PLC data to cloud services offers unmatched flexibility.
Methods to Send PLC Data to the Cloud
There are several architectures for sending PLC data to the cloud, depending on the PLC’s capabilities and your network setup.
1. Direct Cloud Integration (MQTT/HTTP APIs)
Some modern PLCs now support native cloud connectivity. For instance:
- Siemens S7-1500 with MindConnect can push data directly to MindSphere via MQTT or REST API.
- PLCs with built-in MQTT clients can publish sensor values directly to platforms like AWS IoT Core or Azure IoT Hub.
This method is clean and efficient—but only viable if your PLC supports cloud protocols natively.
2. Using Industrial IoT Gateways
Most legacy PLCs don’t support cloud communication directly. In this case, use an industrial IoT gateway that can:
- Read data via Modbus, OPC UA, or other protocols from the PLC.
- Convert it to cloud-friendly formats (MQTT, HTTPS).
- Securely transmit it to your chosen cloud platform.
3. Middleware Applications
Tools like Node-RED, Azure IoT Edge, or Kepware Edge allow data routing and transformation between PLCs and the cloud. Middleware can:
- Add logic (e.g., only send data on value change)
- Integrate with MQTT brokers and REST APIs
- Run on edge computers or industrial PCs
This method adds flexibility and enables edge computing features, but requires some configuration effort.
Key Protocols & Security Considerations
Choosing the right communication protocol and security setup is critical when sending PLC data to cloud environments.
MQTT vs. REST APIs
| Feature | MQTT | REST API (HTTP/HTTPS) |
|---|---|---|
| Protocol | Lightweight publish/subscribe | Request/response |
| Best For | Continuous streaming | On-demand data retrieval |
| Overhead | Low | Moderate |
| Reliability | Good with QoS levels | Depends on implementation |
For industrial IoT, MQTT is often preferred due to its low bandwidth usage and ability to work on unreliable networks.
Security Essentials
- Encryption: Use TLS/SSL to secure all data in transit.
- VPN Tunnels: For private networking between factory and cloud.
- Firewalls: Whitelist only essential ports and IPs.
- Authentication: Use device certificates or access tokens to validate each data source.
Secure configuration is non-negotiable when transmitting critical production data over the internet.
Cloud Platforms Comparison
Different platforms offer distinct advantages for PLC to cloud communication:
| Platform | Key Features |
|---|---|
| AWS IoT Core | Scalable MQTT broker, rules engine, Lambda integration |
| Azure IoT Hub | Deep integration with Azure services, device twin management |
| Google Cloud IoT Core | Lightweight, scalable, but limited device management tools (now deprecated in some cases) |
Note: Always check for current support and pricing models before committing to a platform.
Use Case Example: Modbus TCP to AWS IoT via Gateway
Here’s a simplified step-by-step of how to send data from a PLC to cloud using a Modbus-based PLC and AWS IoT Core.
Step 1: Connect PLC to Gateway
- Configure the gateway to read registers via Modbus TCP (e.g., address 40001).
- Verify connectivity using diagnostic tools.
Step 2: Format Data for MQTT
- Create a JSON payload
Step 3: Secure Gateway to Cloud
- Install device certificates from AWS IoT.
- Configure gateway to publish to AWS IoT Core’s MQTT broker.
Step 4: Set Up Rules in AWS
- Use AWS IoT Rules Engine to route incoming data
This setup enables full cloud-based monitoring and control of your PLC data.
Pitfalls to Avoid
When deploying PLC to cloud connections, be aware of the following:
- Latency Issues: Avoid sending time-critical control commands over high-latency cloud links.
- Data Throttling: Many cloud services limit message rates or payload sizes—optimize accordingly.
- Vendor Lock-In: Avoid over-reliance on proprietary cloud features if multi-cloud flexibility matters.
Final Thoughts
Knowing how to send data from PLC to cloud is a vital step toward building smarter, more connected industrial systems. Whether using direct integration, gateways, or middleware, the goal is secure, reliable, and scalable PLC data to cloud communication.
Need help with cloud-ready industrial connectivity? Explore COME-STAR’s industrial gateways and communication devices—engineered for secure IIoT deployment in challenging environments.
