Endpoint vs. Datapoint
In Unified-E, a operator app retrieves the necessary datapoint values from the associated endpoints every second for real-time display of the current view. The endpoints act as servers and provide read and write access to datapoints.
- Endpoint:
A Unified-E endpoint identifies a data source typically with an IP address. The endpoint adapter describes which protocol to use for communication with the endpoint. All available endpoint adapters can be found here. - Datapoint:
An endpoint usually provides several datapoints that can be read or written. Within Unified-E, datapoint names are used, but a datapoint address must be configured for endpoint communication.
Only the linked datapoints in the view elements bring the operator app to life and enable monitoring or control. For programmers, a datapoint can be compared to a variable, and the data types "numeric", "text", "yes/no", and "table" are supported.
Test Datapoints Online
The configured endpoint datapoints can already be tested online without views by establishing a real communication connection with the endpoint, e.g. PLC controller or database. This is done in the datapoint editor of the respective endpoint. For a successful connection, the endpoint must be properly configured and be in the same network as the Unified-E App Designer.
The entire operator app can already be tested online with a real endpoint connection in the Unified-E App Designer, no operator devices are required. The actual values of the datapoints can be observed in real-time in the editor, allowing for quick diagnosis of address errors.
Table Datapoints
Datapoints with the data type "Table" contain a complete table as a value and are used for arrays, SQL query results with the SQL adapter, or JSON returns with the HTTP adapter. These table datapoints can then be used as a basis for displaying charts or lists.
Script Datapoints
Script datapoints are a type of "virtual" datapoint. When reading and writing, the defined read or write scripts are always executed. The defined script functions can read from other datapoints or write to other datapoints when writing and are created in JavaScript syntax. Script datapoints have no memory, meaning the read value is always calculated first using a script.
For example, if a temperature datapoint with a value in "degrees Celsius" is to be displayed in the unit "Fahrenheit", a script datapoint is the solution for this.
The integrated script editor helps in creating script datapoints. Script datapoints behave like regular datapoints when configuring view elements and can therefore be linked wherever datapoints can be linked.
Local Datapoints
Local datapoints can be freely defined. They have an initialization value and can save the last value even after the operator app is closed, so the last value is retained on the next restart. Depending on the runtime setting, the local datapoint is managed centrally in the Unified-E App Manager or per operator device.
Important applications for local datapoints:
- Intermediate variable for scripts:
Results of a script can be temporarily stored in local datapoints. The values contained therein could then be used in triggers and subsequent scripts. - Operator device-local tab switching:
Areas of a view can be shown or hidden with the view element "state button". Here, it is recommended to use a local datapoint with runtime "per operator device" to control the visibility of areas.