readEx

[ Function ]

Version 1.10

public readEx(
    callback?: (data: Symbol.IReadResultObject | Symbol.IServerReadResultObject) => void
): void;

Version 1.12

public readEx<T = ST>(
    callback?: (data: Symbol.IReadResultObject<T> | Symbol.IServerReadResultObject<T>) => void
): DestroyFunction;

Reads the value of the symbol.

The callback function is called either synchronously or asynchronously, depending on the symbol type used.

Version 1.12: If the API is used in TypeScript code, the symbol type (ST: SymbolType) can be reported to the TypeScript compiler when a symbol is created. This then no longer has to be specified when using this function, although it can be overwritten.

This is a merely an auxiliary programming feature. The browser does not recognize this "type annotation". No check or conversion takes place at runtime.

Parameter

Return value

Available from version 1.10

Sample - JavaScript

var symbol = new TcHmi.Symbol('%s%PLC1.MAIN.sTest%/s%');
symbol.readEx(function (data) {
    if (data.error === TcHmi.Errors.NONE) {
        // Handle result value... 
        var value = data.value; 
        console.log(value); 
    } else {
        // Handle error... 
    }
});

Sample 1 - TypeScript

var symbol = new TcHmi.Symbol('%s%PLC1.MAIN.sTest%/s%');
symbol.readEx(function (data) {
    if (data.error === TcHmi.Errors.NONE) {
        // Handle result value... 
        var value = data.value; // TS does not know the variable type
        console.log(value); 
    } else {
        // Handle error... 
    }
});

Sample 2 - TypeScript

var symbol = new TcHmi.Symbol<string>('%s%PLC1.MAIN.sTest%/s%');
symbol.readEx(function (data) {
    if (data.error === TcHmi.Errors.NONE) {
        // Handle result value... 
        let thisIsAString = data.value; // TS knows this is a string
        console.log(thisIsAString); 
    } else {
        // Handle error... 
    }
});

Example 3 - TypeScript

var symbol = new TcHmi.Symbol ('%s%PLC1.MAIN.sTest%/s%');
symbol.readEx<string> (function (data) {
    if (data.error === TcHmi.Errors.NONE) {
        // Handle result value... 
        let thisIsAString = data.value; // TS knows this is a string
        console.log(thisIsAString); 
    } else {
        // Handle error... 
    }
});