Introduction

TwinCAT HMI Engineering reads all properties of the control from the Description.json file. The properties allow you to transfer data to the control and vice versa. In TwinCAT HMI Engineering, the control can be configured via the Properties window or via the Actions and Conditions editor. The developer can define additional attributes, besides the standard attributes of each framework control.

Description.json must correspond to a given JSON schema. The schema is located in the framework control project under Schema/Control/Description.json. The schema must not be changed. It is used to describe the syntax in Description.json.

In many cases the following user-specific properties are defined in Description.json:

• Attributes (data interfaces)
• Functions
• Events
• Access rights
• User-specific data types