Philips Hue

This part of the sample includes a PUT request to a Philips Hue Bridge (required TwinCAT version: 3.1.4024.10). The Bridge's REST API enables TwinCAT users to control Philips Hue devices from the PLC. The user must have a Philips Hue Bridge available in his network and at least one device connected to it.

Basically, the HTTP client, in this case TwinCAT, sends different values as a JSON document to the bridge (e.g. saturation, brightness, state and color value for a bulb). The bridge answers with another JSON document which shows if the commands have been successful.

Within the setup process, the Philips Hue Bridge randomly generates a user name for a device that acts as HTTP client. This user name can then be used for the communication with the bridge.

Philips offers a “Getting started” tutorial here, which explains how to find the bridge in a network and how to implement a client application: https://developers.meethue.com/develop/get-started-2/
The API description can be found on the same website, but registration is required.

The following sample implements on the one hand a single PUT request and on the other hand a toggling PUT request that is used for a so-called “Blinking mode”. This mode triggers a Philips Hue Go lamp to change the color (between 0 and 65000) every time the timer output is set.