OPC Expert includes a REST API server enabling end users and programmers to easily connect to OPC Expert and exchange (read and write) data. This page includes instructions how to setup all services and programmers may refer to OPC Expert Rest API Server Documentation.

OPC Expert’s REST API server enables client applications to:

  • Read real-time data (read all data, create real-time trends, show real-time updates)
  • Write data (control setpoints)
  • Read historical data (create trends and reports)
  • All data arrives in JSON format
  • Communication support
    • OPC Classic: OPC DA and OPC HDA
    • OPC UA: OPC UA DA and OPC UA HA
    • MQTT: Publisher, Subscriber and Broker
    • Modbus: Modbus Master (Modbus client) and Modbus Slave (Modbus server)
  • REST API server runs on Windows
    • Workstation support Windows XP to Windows 11
    • Server supports Windows Server 2003 to Windows Server 2022
  • REST API client applications
    • On any hardware platform (PC, Mac, Phone, PLC, etc)
    • On any operating system (Android, iOS, iPadOS, Linux, Unix, Windows, etc)
    • Any language (C, C++, Java, Javascript, PHP, Python, VBA, VB Script, etc)

REST API server setup

Users can setup (install) OPC Expert’s REST API server quickly. Example below illustrates how to complete this setup:

  • In OPC Expert’s main menu, select (Tools -> Servers & Services)
  • Ensure to check “OPC Expert UA server” and “REST API server” as below (this will set both up as Windows services) and click button “OK”
  • In OPC Expert, expand “This Computer” and note you are able to see your OPC servers as well as REST API server

Test REST API setup

After setting up OPC Expert REST API server, test connections as follows

  • Subscribe to an item using OPC Expert (this does not have to be an item from the REST API server)
  • Test your setup by right-click above item and selecting “Trend” from right-click menu
  • If you see a trend on the desktop, OPC Expert’s REST API server is working well

Connecting to OPC Expert REST API server

It is easy to connect to OPC Expert REST API server. Users only need to expand each data source in the tree and follow a path to their items as below

Since OPC Expert REST API server follows standard REST architecture, users can easily open trends directly in their browsers from the trend menu by selecting (Options -> Open on local browser):

The following is an example from Microsoft Edge:

Users can also open the same trend on their mobile phone as follows:

Automatic Source Code Generation

OPC Expert can automatically generate source code snippets in a variety of languages. You can right-click an item and follow the right-click menu as below. You will then be able to paste the text into your IDE (integrated development environment).

To generate the Python code snippet, right-click the item, and from the right-click menu, select (REST API Command -> Generate Code Snippet -> Read -> Python) and notice other languages are available as well such as C#, Java, Javascript, VBA, etc)

Python code will now be in Windows Clipboard, you will now have to paste it into your Python IDE (such as IDLE).