--- title: Threshold or value alarm on a KNX or BACnet datapoint in Boss’nX description: Trigger a Boss’nX alarm when a KNX or BACnet measurement crosses a high or low threshold, with hysteresis and delays, or takes a specific value. canonical: https://wiki.can-nx.com/en/guides/boss-point-alarm/ language: en product: Boss’nX audience: - administrateur - installateur context: "Boss’nX on a computer: component editor, KNX or BACnet alarm datapoint in Application threshold" --- # Threshold or value alarm on a KNX or BACnet datapoint in Boss’nX Context: Boss’nX on a computer: component editor, KNX or BACnet alarm datapoint in Application threshold A Boss’nX alarm datapoint monitors a KNX or BACnet measurement of a component: a high or low threshold crossed, with hysteresis and delays, or specific values received. Triggered alarms are then viewed in the supervision’s alarm history. For administrators and installers, on a computer. To compare two measurements with each other, follow [the comparison between two datapoints](https://wiki.can-nx.com/en/guides/boss-point-alarm-comparison/) instead. For Modbus, use [the no-signal delay of the Modbus datapoint](https://wiki.can-nx.com/en/guides/boss-point-modbus/): its fields and units differ from this form. ## Before you start - Your account has **Manage components** in the relevant supervision. - The measurement to monitor is identified: for KNX, its feedback address and DPT, see [the addresses and DPT of a KNX datapoint](https://wiki.can-nx.com/en/guides/boss-point-knx/); for BACnet, the device and object, see [the BACnet datapoint guide](https://wiki.can-nx.com/en/guides/boss-point-bacnet/). - The values and delays intended for the installation are known. The examples in this guide are fictitious. ## Open the alarm datapoint 1. Open **Components** in your bar or through **Menu → Components**, find the component and click the **Edit component** pencil. For a new component, use **Add component** and fill in [the general form](https://wiki.can-nx.com/en/guides/boss-component-edit/). 2. Click **Add point**, or find the datapoint to edit, then fill in its **Label**. 3. For **KNX**, choose the **DPT** and the **Feedback** address confirmed for the measurement, as well as the component’s or datapoint’s gateway. 4. For **BACnet**, choose the **BACnet device** and the object you want. For an analog measurement, check that it is the correct Analog Input, Analog Output or Analog Value object. 5. Check **Alarm** in the datapoint’s header: **Feedback** becomes checked and **Cmd** unchecked. For KNX, the read field is then named **Alarm Address**: check the address it contains. 6. For BACnet, check **Alarm source**, in the datapoint’s options (**Show options** if they are collapsed). Choose **Application threshold** for the conditions described here. **BACnet-native (intrinsic)** belongs to another path, explained in [the component alarm troubleshooting](https://wiki.can-nx.com/en/guides/boss-point-alarm-help/). 7. Under **Level / Severity**, choose **Low**, **Medium** or **High** according to your installation’s convention. Review the datapoint’s role before saving: checking **Cmd** or **Feedback** afterwards removes the alarm mode. To keep a command on the same measurement, create a separate alarm datapoint. ## Monitor a high or low threshold This mode applies to a non-boolean numeric KNX datapoint or an analog BACnet object set to **Application threshold**. 1. In **Trigger**, select **Threshold**. 2. Fill in **Low threshold**, **High threshold**, or both. At least one limit is required; with two limits, the low threshold must be lower than the high threshold. Leave empty a limit you do not monitor: entering zero defines a real limit at zero. 3. Fill in **Hystérésis** (Hysteresis), positive or zero according to the intended setting. In the threshold block, this label stays in French in the English interface. It is the margin for returning to normal; it does not shift the trigger threshold. 4. Fill in **Trigger delay (min)** and **Reset delay (min)** in minutes, with positive or zero values: **0.5** minute equals thirty seconds. Always enter the reset delay you want: left empty, it may reuse the trigger delay instead of returning without delay. 5. Leave the last field, then review everything before saving. The crossing is strict: a value exactly equal to the high or low threshold does not trigger the alarm. The delays rely on the values received and their evaluation: the notification may not appear at the exact second. Fictitious example with a high limit only: **High threshold 28**, **Hystérésis 1**, **Trigger delay 2**, **Reset delay 0.5**. A value above 28 meets the trigger condition. After a high alarm, a value lower than or equal to 27 meets the return condition, with the intended reset delay; a value of 28 keeps the alarm active. With a low limit only, the return happens from the low threshold plus the hysteresis. With two limits, have a hysteresis compatible with the range confirmed. For quick transitions from one limit to the other or an uncertain expected behavior, contact support before changing the settings. ## Monitor a value list This mode applies to a non-boolean numeric KNX datapoint or an analog or multistate BACnet object set to **Application threshold**. The values must match the device’s confirmed encoding. 1. In **Trigger**, choose **Value list**. 2. Under **Trigger values**, click **+ Add value**, then enter the number in the added row. Repeat for each monitored value. 3. Under **Reset values**, click **+ Add value**, then enter the values that return the alarm to normal. 4. Keep at least one value filled in in each list, without putting the same value in both. The trash can on the right of a row removes it. 5. Leave the last field and review both lists before saving. Fictitious example: **3** and **7** trigger, **0** resets. A value missing from the reset list does not return the alarm to normal: enter the return states actually intended. This mode does not offer the delay fields of the **Threshold** mode. Do not change mode just to set a delay: for this need, or for a binary BACnet object whose trigger and normal states must be confirmed, contact support with the datapoint and the result you want. ## Set up the alarm of a boolean KNX datapoint With a boolean KNX DPT, **Trigger on** replaces the numeric modes and offers **Value 1 (True)** or **Value 0 (False)**. Choose the value that matches the installation’s real alarm state. Do not change the DPT to get the threshold fields. To invert an existing alarm, trigger on zero or guarantee its return to normal, have the configuration confirmed by support first. ## Save the alarm 1. Click **Create** or **Save**. 2. Reopen **Edit component** and check the protocol, the source, the values and the delays that were kept. Before saving, **Back**, at the top left, discards the component’s pending changes. After saving, a correction requires saving again. ## Check the result - Check that the monitored measurement is actually received: declaring an object, an address or an alarm does not prove it. - Run a trigger test on the hardware, then view [the alarm history](https://wiki.can-nx.com/en/guides/boss-alarms-consult/) in the correct supervision. Saving validates the configuration, not the actual triggering. ## Troubleshooting - Validation blocks, or the expected alarm does not appear or does not return to normal: follow [the component alarm checks](https://wiki.can-nx.com/en/guides/boss-point-alarm-help/). - To monitor missing messages (heartbeat) or pause the datapoint’s notifications, see the same guide. If the problem persists, contact support@can-nx.com with the supervision, the component, the datapoint, the configured conditions and the result you want. French labels: **Composants → Modifier le composant**, **Ajouter un point**, **Alarme**, **Re.Etat**, **Adresse Alarme**, **Afficher les options**, **Source d'alarme**, **Seuil applicatif**, **Niveau / Gravité → Basse / Moyenne / Haute**, **Déclenchement → Seuil / Liste de valeurs**, **Seuil bas**, **Seuil haut**, **Délai déclenchement (min)**, **Délai reset (min)**, **Valeurs de déclenchement**, **Valeurs de désactivation**, **+ Ajouter une valeur**, **Déclenchement sur → Valeur 1 (Vrai) / Valeur 0 (Faux)**, **Créer**, **Enregistrer**.