---
title: "Boss’nX alarm rules: compare two KNX measurements in bulk"
description: "Create Boss’nX alarms in bulk that compare two KNX datapoints of the same component, such as supply and return: tags, operator, pairing and checks."
canonical: https://wiki.can-nx.com/en/guides/boss-tag-alarms-comparison/
language: en
product: Boss’nX
audience:
  - administrateur
  - installateur
context: "Boss’nX, supervision: Alarm rules page, Comparison trigger type"
---

# Boss’nX alarm rules: compare two KNX measurements in bulk

Context: Boss’nX, supervision: Alarm rules page, Comparison trigger type

The **Comparison** trigger type on the **Alarm rules** page creates, in each component, an alarm that compares a source datapoint with another datapoint of the same component, identified by its tag, for example a supply temperature and a return temperature. A single operation thus covers all the components whose datapoints carry these tags.

Intended for the administrator or installer authorized to manage components. To set up a single comparison in one component, follow [the comparison in a component alarm](https://wiki.can-nx.com/en/guides/boss-point-alarm-comparison/) instead.

## Before you start

- The measurements, units and parameters of the two datapoints allow the comparison you want.
- Both datapoints are KNX datapoints that have a read address. The source datapoint must be compatible with this mode: a boolean source datapoint is shown as incompatible.
- The selection, the limit of five hundred datapoints and the handling of partial results are described in [the creation guide](https://wiki.can-nx.com/en/guides/boss-tag-alarms-create/).

## Choose the two tags and the condition

1. Open **Menu → Alarm rules**.
2. In the **Tag** field at the top, choose the tag of the source datapoints. Check the **Create** view.
3. In a new preparation, choose **Comparison** under **Trigger type**. If you had already filled in another type, leave and reopen this page before sending anything, to start again from a definition to check.
4. Under **Compare to (tag B)**, choose the tag of the partner datapoints.
5. Under **Operator**, choose the comparison you want: greater than ( > ), greater than or equal ( >= ), less than ( < ), less than or equal ( <= ), equal ( == ) or not equal ( != ).
6. Fill in **Hysteresis (tolerance)** according to the planned setting; you will check its effect in the confirmation preview. If the expected condition remains ambiguous, consult support before creating the alarm.

Fictional example: compare **Supply temperature** and **Return temperature** of the same boiler, with the corresponding tags. Use the datapoints actually configured and the condition planned for your installation.

## Check the pairing of each row

The partner is searched for in the same component as the source datapoint, excluding the source datapoint itself. In **Measure points**, expand the locations or use **Expand all**.

| Result on a row | Action |
| --- | --- |
| Partner shown with its label and address | Check that it is the right datapoint. A single partner is offered automatically. |
| **Ambiguous — pick the target:** | Open the **— pick —** list, then select the right label and its address. The row may then become eligible and be checked automatically. |
| **No “…” point in this component** | Check tag B and the datapoints of this component: a datapoint located in another component does not qualify. This row cannot be created without a partner. |
| Incompatible datapoint | Check the DPT and the expected type of monitoring. Do not change the DPT to make the row artificially eligible. |

Uncheck unwanted rows, even if their partner is offered automatically. The **paired**, **ambiguous** and **without partner** totals help you check the batch. Collapsed branches keep their selections.

Changing the source tag, tag B or the trigger type clears the manual choices of partners. Check each pairing again after such a change.

## Confirm the creation

1. Check **Severity** and **Trigger delay (min)**. **Comparison** mode shows **Auto-reset once the condition is no longer true.** and does not offer the **Reset delay (min)** field.
2. Fill in the options you want, the **Alarm names** and the **Tag of created alarms**.
3. Click **Apply to selection (…)**. In **Confirm creation**, check the names, the number of components and the condition with the partner shown.
4. Use **Back** to correct before sending, or **Confirm**, then wait for **Report**.
5. Check the results and the rejections before clicking **Close**.

## Check the result

Choose the tag of the created alarms and find the new datapoints in [Existing alarms](https://wiki.can-nx.com/en/guides/boss-tag-alarms-existing/). Each new item is a comparison alarm datapoint: the creation adds no command to the monitored datapoints. Then test the condition on the installation.

## Troubleshooting

After a partial result, check the datapoints already created and do not recreate the items already present.

For a partner that cannot be found, an uncertain condition or a persistent failure, contact support@can-nx.com with the supervision, the component, the two tags and the desired result.

French labels: **Comparaison**, **Comparer à (tag B)**, **Opérateur**, **Hystérésis (tolérance)**, **Ambigu — choisir la cible :**, **— choisir —**, **apparié**, **sans partenaire**.