System.Tag.subscribe¶

Description¶

Subscribing to a tag will retrieve its value, path, quality, and time when the tag changes.

Grammar¶

System.Tag.subscribe(paths: Array, callback: (value: {

Time: string;

Path: string;

Value: any;

Quality: number;

}=>void): () => void

 - Parameter

    paths - Tag paths

    callback - A callback function used to handle notifications of changes in tag values

 - Return

    Unsubscription function

Code Example¶

First create a tag group and select the refresh type of the tag group as "Value Change".

Then create a tag and check the tag group you just created.

Finally, when you subscribe to the "Device: Rotate" tag, you will receive the pushed data and print out the new value when the tag changes.

const unsubscript = System.Tag.subscribe(['@Device: Rotate'], (value) => {
    console.log('subscribe', value.Value);
});

// Unsubscribe after 60 seconds
setTimeout(() => {
    unsubscript();
}, 1000 * 60);