# Recording Mode and Thresholds

A sensor records in one of two modes:

| Mode | What the sensor uploads |
|---|---|
| **Continuous** | Everything it measures, all the time |
| **Triggered** | Nothing until shaking crosses its threshold. Then it uploads from up to 60 seconds before the crossing until the shaking stops, and Grillo Cloud records it as a [trigger](/dashboard/triggers) |

In both modes the sensor sends its health reports every minute or less, so it shows as [online](/dashboard/sensors/sensor-status) either way.

By default the project's [plan](/dashboard/plans) decides the mode: sensors on the Structural plan record triggered, and sensors on every other plan record continuous. Owners and admins can give a sensor its own mode.

## See a sensor's mode and threshold

Open **Sensors** and select a triggered sensor. Its details show a summary such as **Triggered · 5 mg threshold · 12 triggers since boot · last trigger 2 hours ago**, and the **Trigger threshold**, marked **project default** or **set for this sensor**. The trigger count starts again from zero when the sensor restarts.

![Sensor details for a triggered sensor, with its threshold and recent triggers](/img/screenshots/sensor-recording.png)

Below it, **Recent triggers** lists the sensor's latest triggers.

## Change a sensor's threshold

Owners and admins can change the threshold from the sensor's details:

1. Next to **Trigger threshold**, select **Edit**.
2. Enter a threshold between 1 and 2000 mg, in steps of 0.5 mg.
3. Select **Save**.

To go back to the project's threshold, select **Edit**, then **Use project default**.

The sensor applies the change at its next check-in, usually within a minute. Until then its details show **Pending — device has not applied this yet**.

## Change a sensor's recording mode

Owners and admins can set a sensor's mode and all of its trigger settings:

1. Open the sensor's details and select **Edit**.
2. Under **Recording mode**, choose:
   - **Follow project plan**, to use the plan's mode. The option shows the mode the plan currently uses.
   - **Continuous**
   - **Triggered**
3. For a triggered sensor, leave **Use project trigger defaults** on, or turn it off to give the sensor its own settings.
4. Select **Update Device**.

![Recording mode settings in the Edit Sensor dialog](/img/screenshots/sensor-recording-mode.png)

Below the settings, the dialog shows what the sensor last reported: its mode, the number of triggers since it started, and whether it is recording an event now.

### Trigger settings

| Setting | Range | Grillo default |
|---|---|---|
| **Trigger channel** | **Any horizontal**, `HNE` (east), `HNN` (north), or `HNZ` (vertical) | Any horizontal |
| **Threshold (mg)** | 1 to 2000 mg | 5 mg |
| **Pre-event (s, max 60)** | Seconds kept from before the threshold was crossed, 0 to 60 | 60 s |
| **Post-event (s, max 300)** | Seconds the sensor keeps recording after the shaking last crossed the threshold, 0 to 300 | 60 s |
| **Alert level (mg)** | The level for [trigger alerts](/dashboard/alerts). Leave **Use project alert level** on to use the project's | The project's level |

**Any horizontal** triggers when either horizontal axis crosses the threshold. A vertical-only knock may not trigger it.

## Set the project's trigger defaults

On Structural projects, owners and admins can set defaults for all of the project's triggered sensors:

1. Open **Project Settings**.
2. Under **Trigger defaults**, set the trigger channel, threshold, pre-event, and post-event times. Leave a field empty to use the Grillo default.
3. Select **Save**.

Sensors that use the project trigger defaults apply the change at their next check-in. Sensors with their own settings keep them.

## Choose a threshold

The right threshold is above the normal vibration at the sensor's location and below the shaking you want to record.

- Start with the default of 5 mg.
- If a sensor records triggers all day from machinery, lifts, or traffic, raise its threshold. Look at the Horizontal PGA of those triggers on the [Triggers page](/dashboard/triggers) and set the threshold above them.
- If it records nothing during events you can feel, lower it.

A sensor that triggers more than 15 times in an hour is in a **trigger storm**. Grillo emails the alert recipients once, with a suggested threshold. See [Trigger Alerts](/dashboard/alerts#limits).

## Which sensors support triggered recording

Triggered recording needs current Grillo Pulse firmware. If a sensor's firmware cannot record triggered, its details show **Not reported by this firmware**. [Update its firmware](/dashboard/sensors/firmware-updates), or [contact Grillo Support](/support/contact).

Settings are saved on the sensor, so it keeps recording the same way after a restart.