Communication With Other Elements

This describes how data is transferred between multiple elements. For example, weather data or turn signals can be calculated simultaneously.

Global Variables

To communicate with other elements within the same project, use the variable prefix global.

Tip: Use the Function Block STATUS and GETSTATUS to transfer central values.

Note that when a global variable is changed, all affected elements are recalculated, which can lead to increased cycle time.

Since the order of calling a global variable matters, a double cycle is run when changing the global variable to reduce reaction time.

To list all used elements, you can right-click on the global variable in the active Preview. If the variable is used in another element, these will be displayed under Used By.

Use As Databases

It is not recommended to use the prefix in databases, as this can lead to increased PLC load.

The above example should not be used. Instead, the result of the calculation should be made available globally.

In individual elements, the result can then be processed.

Edge Detection

Edges cannot be processed via a global variable, as the value may persist for more than one cycle. Or it might never occur when resetting. Instead, use edge detection in each element.

While global.count1 does not work correctly, an alternating signal is used for global.count2. This remains statically true or false after processing. Thus, an edge can be generated. Alternatively, a timer could be used, but this might lead to time-critical issues.

In this example, a number is incremented on an edge because the value TRUE is interpreted as a 1.

Superglobal Variables

The so-called superglobal variables are used to exchange data between multiple projects on the same Server or the same Network. The interface Superglobal Variables is used for this.

The method is further described in the chapter Communication With An Interface.

Hyperglobal Variables

With this method, data can be communicated between multiple servers via Cloud in real time. The communication takes place via the interface Hyperglobal Variables.