In this blog, we will discuss what a PLC is and how IoT gateway devices can be used to send PLC machine state data as telemetry messages to the cloud. The data provided by the PLC can be stored in a structured format within a database and utilized for purposes such as reporting, generating alerts, creating dashboards, and more. With the help of IoT gateway connectivity, we can also request specific actions to be performed by the PLC. These IoT gateways enable bi-directional communication between PLCs and the cloud.
What is a PLC?
What is an IoT Gateway?
An IoT Gateway plays a vital role in an IoT ecosystem by acting as a bridge between edge devices (e.g., sensors, actuators, PLCs) and cloud platforms. It performs tasks such as collecting, processing, and transmitting data.
Key Functions of IoT Gateway:
- Protocol Translation: Converts industrial protocols like OPC-UA or Modbus into IoT protocols such as MQTT or HTTPS.
- Data Collection: Collects sensor data from multiple edge devices.
- Data Processing: Filters and pre-processes large amounts of sensor data, transmitting only relevant data.
- Cloud Connectivity: Establishes secure communication with cloud platforms such as Azure IoT Hub or AWS IoT Core.
- Bi-Directional Communication: Facilitates communication both from device to cloud and cloud to device.
- Programming Languages: Supports high-level programming languages like Python or JavaScript for gateway programs.
Using IoT Gateway to Enable Bi-Directional Communication Between PLC and Cloud
If you’d like to know more about enabling communication between an IoT Gateway and the Azure IoT Hub, please refer to our other blog here: https://corecotechnologies.com/development/bi-directional-communication-between-iot-devices-and-azure-services/
PLC Machine State Synchronization with Cloud
Certain applications require actions to be performed by the PLC from a remote location. To develop such applications, the following are necessary:
- PLC Interfaces:
- An interface to provide the current machine state for the IoT Gateway to collect periodically.
- An interface to accept requests from the cloud via the IoT Gateway and perform the necessary actions.
- Cloud Receiver Program:
- This program should provide an external interface for the IoT Gateway to send PLC state data.
- It can be developed using programming languages like Python or JavaScript, and it interacts with cloud services such as Azure IoT Hub.
Once these interfaces are established, the IoT Gateway acts as a bridge, using Ethernet or serial ports to connect with the PLC. It pre-processes the data and sends only relevant information to the cloud. At the same time, it enables cloud-based actions to be communicated to the PLC, creating a robust remote-control system.
Handling Connectivity Issues:
One major challenge in this system is managing connectivity issues between the PLC, IoT Gateway, and the cloud. Steps to address this include:
- Generating Alerts: Notify stakeholders immediately of any connectivity disruptions.
- Pausing Actions: Stop sending actions to the IoT Gateway if the PLC-Gateway link is down.
- State Synchronization: After restoring connectivity, drop outdated PLC state data stored in the cloud and replace it with the latest data from the PLC.
Handling Connectivity Issues:
One major challenge in this system is managing connectivity issues between the PLC, IoT Gateway, and the cloud. Steps to address this include:
- Generating Alerts: Notify stakeholders immediately of any connectivity disruptions.
- Pausing Actions: Stop sending actions to the IoT Gateway if the PLC-Gateway link is down.
- State Synchronization: After restoring connectivity, drop outdated PLC state data stored in the cloud and replace it with the latest data from the PLC.
IoT Gateway devices facilitate bi-directional communication between PLCs and cloud platforms, enabling better control and monitoring of industrial systems. By addressing connectivity challenges and ensuring synchronized machine states, IoT Gateways help businesses improve reliability and enhance system efficiency. This integration plays a crucial role in modern industrial applications, making automation seamless and responsive.
If you found this blog insightful, explore more topics on industrial automation and IoT on our website. For further discussions or inquiries, feel free to contact the author at [email protected]. We’d love to hear your thoughts!
