Communication with Interfaces

The communication with the interfaces is done via the variables in.COM and out.COM. Where COM can have any name. Then you can select the interface on the right side of the editor under Communication. All interfaces assigned to the project are listed there. In the list below the selection field, the telegrams can be defined. Unlike other systems, you can enter multiple data points per variable here. It is also possible to link the variable via Drag&Drop directly from the interface under Installation.

In this case, you must correctly specify the data type. Unlike the standard of the KNX bus system, a universal type is used here and not the DPT/EIS types.

Structure of the Editor

The dialog box in the editor allows interfaces to be linked without affecting the programming of the element.

In the example shown above, a SONOS speaker was controlled with a KNX button. In addition, an analog value was linked to a status.

The communication variable status sends to group address 1/0/5 and reacts to changes from 1/0/5 and 1/7/5. The question mark queries the status of 1/7/5 during initialization.

For the values Tr_UP and Tr_DW, sending was deactivated by unchecking the checkbox.

The red marked values (Tr_Play and Tr_Stop) were not found in the PLC and are therefore ignored. If the program has been successfully tested, these values can be deleted without affecting the application.

Tip: Right-click on a communication variable to find its occurrence in the PLC.

Triggers

The input signals are filtered. Repeating values are ignored. For this purpose, there is the data type trig, trig_p etc. These generate an edge when a telegram arrives. With several gateways on the same interface, only the current gateway generates a pulse. This prevents multiple pulses in succession.

Linking Values

You can link communication objects via Drag&Drop directly to an element from the structure. For this purpose, any objects with the following symbols can be dragged in the installation.

Symbol	Description
	Object can be read.
	Object can be read and written.
	This is a constant. This value cannot be read or described.

The corresponding interface is automatically selected. This means you do not need to select the interface beforehand. Dragging over it is sufficient. You also do not need to consider whether the interface is correct. For example, if a KNX object is dragged into a PLC, the variable will be correctly assigned accordingly. Note that only the first entry of a communication variable can be sent.

Tip: Under the individual objects in the Installation, the referencing with the respective elements under the objects is displayed. This is helpful when searching for errors.

Sending Values

Only the first data point sends to the bus if the checkmark on the right side is activated. All other objects indicate the state. An example for the KNX bus: If you look at a switching actuator in the ETS, there are usually two communication objects there. One for switching the actuator and one status object (can also be contained in the switch object). Optimally, you can insert each group address as a data point into the interface configuration. This way, the state is displayed on the visualization immediately. And not just when switching the actuator.

Only changes to a variable are transmitted to the interface. The change is reset upon receipt to the same variable. This means that when receiving a change to in.COM, the output out.COM is not sent. This requires special attention when delaying values.

Also always note the number of telegrams an interface sends. Because too many telegrams block the BUS. This can only be improved by a further separate line. If a variable sends fast pulses, this can lead to overwriting the buffer and thereby deleting telegrams of the variable. This can lead to unwanted effects. Therefore, definitely slow down the variable.

Repeated Sending of the Same Value

A special case is sending the same value. This can be implemented in several ways.

If the value is a boolean value, trig_p or trig_n can be used directly as the data type. trig_n sends FALSE and trig_p TRUE as soon as a positive edge is generated on the output out.COM.

Another method is setting NULL. This can be programmed with several possibilities. The simplest method is using the function block SEL.

Initialization After Restart

When starting the server or with new telegrams, these are initialized if a ? without space is before the telegram. For example, ?1/4/22.

Warning: If in the ETS the first group address of the switching actuator is a central command, this can cause a central on or off when reading. Therefore always define the switch address as sending.