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How to Set Data Point Values

Most data points in Mango read values automatically — on a polling interval or by receiving updates from a device. But many protocols also support writing values back to the device. This lets you change setpoints, flip switches, send commands, or update configuration registers directly from the Mango UI.

Prerequisites​

Before you can set a point's value, two conditions must be met:

  1. The data source protocol supports writing. Most industrial protocols do (Modbus, BACnet, OPC-UA, MQTT, SQL), but some read-only sources (like HTTP Retriever or Virtual) may not.
  2. The data point is configured as settable. In the point's configuration, enable the Settable (or Read & Write) option. Read-only points do not display set controls in the UI.

Setting values from the UI​

Watch list​

The fastest way to set a value is from a Watch List:

  1. Open Watch List from the main menu
  2. Hover over the point's current value
  3. Click the pencil icon that appears
  4. Enter the new value in the input field
  5. Click Set or press Enter

The value is sent to the device immediately. The displayed value updates once the device confirms the change (or on the next poll cycle).

Setting a data point value from the Watch List using the pencil icon

Point details page​

The Data Point Details page always shows the set-point control (for settable points) below the point's current value and chart:

  1. Navigate to Data Point Details for the target point
  2. Enter the new value in the Set point input
  3. Click Set

The set-point control on the Data Point Details page

Custom dashboard pages​

On custom pages built with the Dashboard Designer or code editor, you can use set-point components:

  • <ma-set-point-value> — A component that provides a set-point input for a specific data point
  • <ma-switch> — A toggle switch for binary points
  • <ma-slider> — A slider for numeric points within a range

These components bind to a point by XID and send write commands through the REST API.

Data type considerations​

The input format depends on the point's data type:

Data TypeInput FormatExample
BinarySelect from two states (e.g., On/Off)true or false
MultistateSelect from defined states0, 1, 2 (integer value)
NumericDecimal number72.5
AlphanumericFree textHVAC_MODE_AUTO

What happens when you set a value​

  1. Mango sends a write command to the device through the data source protocol (e.g., a Modbus write register command, a BACnet WriteProperty request)
  2. The device processes the command and (typically) confirms the new value
  3. On the next poll or event update, Mango reads back the confirmed value
  4. The point's history logs the change with a timestamp
note

There may be a brief delay between setting a value and seeing it reflected in the UI. This depends on the polling interval and the device's response time.

Permissions​

Only users with set permission on a data point can change its value. Permissions are configured per-point or inherited from the data source. See Users & Permissions for details.