SubscribeToTag

Called to subscribe to a notification of a state change of a tag.

Function

number SubscribeToTag(name: string, updateRate: number, equipment: object, callback: function);

Parameters

Name	Type	Description
name	String	The tag name, this must exist within the tag manager. The name is case sensitive
updaterate	Number	The number of milliseconds that represents the desired update rate of the subscription
equipment	Object	An object that is associated with the subscription, this object will be the ’this’ reference within the callback function. If no object is required then ’null’ may be passed, this will cause the ’this’ reference to refer to the global object
callback	Function	Reference to the callback function that will be invoked when an update occurs

Return Value

A numeric identifier that is unique for this subscription, it may be saved for later use. It a required parameter of the function used to unsubscribe to updates

Example

Subscribe to a tag, then change its value, invoking the callback:

var _tag1;

function OnSimulationStart()
{
    //-- subscribe to tag
    _tag1 = SubscribeToTag("Tag1", 500, null, Tag1ValueChanged)

    //-- set value = 5
    SetTagValue(_tag1, 5);
}

function Tag1ValueChanged(name, id, value, quality)
{
    if(quality == 192) // GOOD
    {
        LogDebug("New value for " + name + ": " + value)
    }
    else
    {
        LogError("Tag '" + name + "' has a bad quality: " + quality)
    }
}

function OnSimulationStop()
{
    //-- example to unsubscribe to Tag1
    UnSubscribeToTag(_tag1);
}