On-demand Read widget

The On-demand Read widget shows a tag's value with a Read now button. Clicking it asks the gateway to read that tag from the physical device immediately — you don't wait for the next scheduled poll.

It pairs well with read-on-demand tags (tags whose interval read toggle is off on the device page): those tags are never polled automatically, so this widget is how you fetch a fresh value from the dashboard.

Using it

1. Add the widget from Add Widget → On-demand Read and bind it to a device tag on the Data tab.
2. Click Read now. The gateway reads the tag and the value appears in the widget within a few seconds, along with a Last read timestamp.
3. If the read fails (sensor unreachable, gateway busy with another read), the widget shows the error briefly.

Good to know

• Gateway devices only. On-demand reads work for devices connected through a gateway (RS485/Modbus, I2C, SPI, and other gateway-mediated protocols). The button is disabled for other device types and while the device is offline.
• Rate limited. One read per device every ~5 seconds. The button enforces the same cooldown.
• Not stored in history. On-demand read values are streamed live to your dashboard but are not written to telemetry history — they won't appear in charts or exports. Regular polled readings are unaffected.
• Alert rules still evaluate on-demand values, so a threshold breach caught by a manual read will still fire your configured alerts.

Prefer reading from the device page instead? Each tag row there has the same Read now action — see pause device reads.