KNX Examples

Welcome to the section where you can find various examples how you can use the KNX Core project.

Example: Read the status of a lamp

The LampReadExample.java demonstrates how to send a read request to fetch the lamp status.

// send a read request to the KNX actuator
client.readRequest(knxGroupAddress);         

// this is the status pool that holds all status information which have been requested
var statusPool = client.getStatusPool();     
// the status pool will translate the byte array from KNX into boolean value
var isLampOn = statusPool.getValue(knxGroupAddress, DPT1.SWITCH).getValue();

Example: Switch on the lamp

The LampOnExample.java demonstrates how you can switch on a lamp for a given KNX Group Address with a pre-defined value. The KNX Client is flexible and gives you various ways how to achieve it:

Switch on by a data point type specific value (e.g. for DPT1 it would be boolean)

client.writeRequest(knxGroupAddress, DPT1.SWITCH.of(true));

Switch on by a human-friendly text (e.g. on/off for DPT1.SWITCH and enable/disable for DPT1.ENABLE`)
```
client.writeRequest(knxGroupAddress, DPT1.SWITCH.of("on"));
```

Switch on by byte or byte-array (more intended for automation processes)

client.writeRequest(knxGroupAddress, DPT1.SWITCH.of((byte)0x01));

Example: Switch on/off the lamp twice times (write sequence)

The LampWriteExample.java demonstrates how to send a sequence of values to the KNX actuator. Given example below we want to switch on/off the lamp twice times (on, off, on, off).

var writeGroupAddress = GroupAddress.of(1, 2, 0);
var dpt = "1.001";  // KNX data point type ID (=DPT1.SWITCH)
var values = new String[]{"on", "off", "on", "off"};

// iterate for each value
for (final String value : values) {
    // translate the human-friendy text into a KNX compatible data point value of DPT 1.001
    // and send to the KNX actuator
    var knxValue = DataPointRegistry.getDataPointType(dpt).of(value);
    client.writeRequest(writeGroupAddress, knxValue);
}

Example: Toggle the lamp

The LampToggleExample.java demonstrates how to toggle the lamp:

If the lamp is off then it will be switch on.
If the lamp is on then it will switch off.

The workflow is to request a read status of the lamp to distinguish if the lamp is currently on or off. As soon we know the status the current status will be inverted (off -> on and on -> off) and sent to the KNX actuator.

In KNX it is common that we have a separate KNX Group Address for status and for setting.

var readGroupAddress = GroupAddress.of(1, 2, 3);    // the KNX Group address to fetch the current lamp status
var writeGroupAddress = GroupAddress.of(1, 2, 0);   // the KNX Group Address for set new lamp value ('on' or 'off')

// send read request and fetch the current lamp status 
client.readRequest(readGroupAddress);
var lampStatus = client.getStatusPool().getValue(readGroupAddress, DPT1.SWITCH).getValue();

// toggle the value (off -> on, on -> off)
var lampStatusInverted = !lampStatus;

// now send the write request to set the new lamp status
client.writeRequest(writeGroupAddress, DPT1.SWITCH.of(lampStatusInverted));

For more examples, see the examples package

pitschr/knx-examples

KNX Examples

Example: Read the status of a lamp

Example: Switch on the lamp

Example: Switch on/off the lamp twice times (write sequence)

Example: Toggle the lamp