---
title: Pool’nX KNX group monitor and telegram logging on SD card
description: Watch KNX telegrams live, read or write a group address, and view or download the telegram history recorded on the SD card of the Pool’nX.
canonical: https://wiki.can-nx.com/en/guides/pool-local-monitoring/
language: en
product: Pool’nX
audience:
  - administrateur
  - installateur
context: "Pool’nX local configuration site: KNX Group Monitor and KNX Datalogging"
---

# Pool’nX KNX group monitor and telegram logging on SD card

Context: Pool’nX local configuration site: KNX Group Monitor and KNX Datalogging

The local configuration site of the Pool’nX shows the KNX bus telegrams live, sends reads and writes to a group address and displays the history of the telegrams recorded on the SD card.

Intended for the integrator who tests the pool addresses or looks for a past telegram, without starting ETS. To open the site, follow [signing in to the local configuration site](https://wiki.can-nx.com/en/guides/pool-local-config/).

## Before you start

- You are signed in to the local configuration site of the gateway.
- The browser supports WebSockets, which the group monitor needs.
- For the history, an SD card is inserted in the **SD CARD** reader on the front panel: see [Pool’nX wiring](https://wiki.can-nx.com/en/guides/pool-install-wiring/).

## Follow the telegrams live

1. In the menu, open **KNX Group Monitor**.
2. Check that **WebSocket status :** shows **Open**. The telegrams are listed with **No.**, **Time**, **Service**, **Priority**, **Source**, **Destination**, **Route** and **Value**.
3. Tick **Group addressed** and **Physically addressed** to show one or the other type of destination, and choose **2-Stage** or **3-Stage** for the display of group addresses.
4. To see only certain addresses, enter a pattern in **Filter**, for example **1/2/3 4/2/\* !1/2/5** (example).
5. Untick **Scroll** to freeze the list while you read it; tick **Raw Data** to show the bytes received. **Clear table** clears the displayed list.

**Busload:**, **Repeated:** and **Busvoltage:** give the bus load, the repeated telegrams and the bus voltage.

| Filter pattern | Effect |
| --- | --- |
| **3** | Level equal to 3 |
| **2-7** | Level between 2 and 7 |
| **1,3,5** | Level equal to 1, 3 or 5 |
| **\*** | The whole level |
| **1/2/\*** | The whole 1/2 group |
| **1/2/3 4/5/6** | Either address: several patterns combine with OR |
| **1/2/\* !1/2/5** | The whole 1/2 group except 1/2/5: a pattern prefixed with ! excludes |

Physical addresses are written with dots, for example **1.1.10**. An empty filter shows everything.

## Read or write a group address

1. In the send row, enter the address in **Group**, for example **5/1/7** (example).
2. Click **Read** to request the value: the response appears in the telegram list.
3. To write, choose the **Type**, from **1Bit** to **14 Byte string**, enter the **Value**, then click **Write**. With **n Byte**, enter the bytes in decimal, separated by spaces.
4. To repeat the write, tick **Cyclic**, enter the interval in **Seconds**, from 0.1 to 60, then click **Write**. To stop it, untick **Cyclic** and click **Write** again, or leave the page.

The **+** button adds a send row for another address.

A write is sent on the KNX bus and controls the devices concerned, including the pool if the address is a Pool’nX command. Test on an address whose effect you know.

## View the telegram history

1. Open **KNX Datalogging**.
2. At the top of the page, check the recording medium: **Datalogger on SD-Card** with the total and free space of the card, or **Datenlogger internal/SD-Karte** (recording on the built-in memory, eMMC).
3. Fill in **From** and **To**, date and time, or click **Last 24h**.
4. Fill in the number of **Rows**, 10000 by default, and if needed a pattern in **Filter**, with the same syntax as the group monitor.
5. Click **Data request**. **More..** loads the next rows; **Clear table** clears the displayed list.
6. Click **Download to file!** to save the telegrams of the period in a text file.

The download only takes positive patterns into account: an exclusion prefixed with ! only applies to the displayed list.

At 3 telegrams per second, that is a bus load of 10%, logging takes up about 2 GB per year.

## Check the result

- Pressing a KNX push-button of the installation appears immediately in the group monitor, with its source and its value.
- After **Read**, the response of the device appears in the list.
- The history of a known period contains the expected telegrams.

## Troubleshooting

| Message or symptom | Cause and action |
| --- | --- |
| **WebSocket status :** **Closed** | The monitor is not connected to the gateway. Reload the page and check that the browser accepts WebSockets. |
| **WebSocket not connected** when sending | The read or the write was not sent. Wait for **Open**, then send again. |
| No telegram displayed | Check the filter, and that **Group addressed** or **Physically addressed** is ticked. |
| **No SD card detected. Insert an SD card to record data.** | No telegram is recorded. Insert an SD card in the **SD CARD** reader. |
| **Data is currently being recorded on internal memory (eMMC). Inserting an SD card is recommended — it is more reliable for data logging.** | Insert an SD card: it is more reliable for continuous logging. |
| **Failed to load data** | The gateway did not return the history. Shorten the period or reduce the number of **Rows**, then try again. |

For other situations, see [Pool’nX troubleshooting](https://wiki.can-nx.com/en/guides/pool-help/). If the problem persists, write to support@can-nx.com with the gateway name, the page concerned and the message displayed.