---
title: "Crestron and KNX: select group addresses and objects"
description: Choose up to 250 KNX group addresses for a Crestron configuration in Link’nX, then check object numbers from 1 to 255 and the C, R, W, T and U flags.
canonical: https://wiki.can-nx.com/en/guides/link-crestron-addresses/
language: en
product: Link’nX
audience:
  - administrateur
  - installateur
context: "Link’nX web: Crestron configuration created with KNX addresses, selection window and object table"
---

# Crestron and KNX: select group addresses and objects

Context: Link’nX web: Crestron configuration created with KNX addresses, selection window and object table

In **Create with KNX addresses** mode, a Crestron configuration in Link’nX is built from the group addresses of the uploaded ETS file: up to 250 addresses, each with an object number and communication flags to be matched with the Crestron programming.

Intended for installers and administrators, at creation or after the **Edit** pencil of a configuration created this way.

## Before you start

- The parameters of the [Crestron declaration](https://wiki.can-nx.com/en/guides/link-crestron-create/) are filled in.
- The right [ETS file is uploaded in KNX](https://wiki.can-nx.com/en/guides/link-knx-file/). A filter saved in **KNX Configuration** does not replace the boxes of the Crestron window.
- The addresses belong to the DPT families **1, 2, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 and 18**, with the subtypes suited to the programming. The table offers no field to correct a DPT. For an address without a known DPT, a DPT 3, another family or a doubt about compatibility, contact support before saving the selection.

## Choose the KNX addresses

1. Click **Select KNX addresses**. The window shows **Max: N/250**, with the number of addresses selected.
2. Use **Filter...** to search for part of the name or of the address. Check **Activate case sensitivity** to distinguish uppercase from lowercase, which is ignored at first.
3. Check the addresses you want. **Select all visible** adds the displayed results; **Unselect all visible** removes them. Addresses hidden by the search remain selected: clear the search to check everything.
4. Stay at **250 addresses maximum**. After **More than 250 addresses selected!**, close the warning and check the selection again: the excess addresses are not all kept.
5. Click **Save** in the window to carry the selection over into the table of the form.

## Check the object numbers and flags

The table shows the columns **Object**, **Name**, **Address** and **Flags**.

- **Object**: an added address receives the lowest free number, starting from 1. If the Crestron programming expects another number, change it in its cell: a whole number from 1 to 255, different for each row. Check each match between object number and KNX address with the Crestron programming.
- **Flags**: **Communication (C)**, **Read (R)**, **Write (W)**, **Transmit (T)** and **Update (U)**. When an address is added, C, W and T are checked; R and U are not. Apply only the choices established for your programming. To determine their effect on the exchanges of your installation, have this choice validated by support before changing them.

## Remove an address

Reopen **Select KNX addresses**, uncheck the address and click **Save**. The addresses kept retain their **Object** number and their flags; an address added afterwards takes the lowest free number, possibly that of the removed address. Do not use a removal followed by an addition as a troubleshooting method without then checking these matches.

## Save the configuration

1. Make sure that the Crestron programming matches the resulting table.
2. Click the **floppy disk at the bottom right of the main form**. **Save** in the address window does not replace this final validation.
3. Wait for **Success!** and the return to the list.

## Check the result

Reopen the configuration with **Edit** and review each row against the Crestron programming, then test a command from it.

## Troubleshooting

- The address list is empty: check the [ETS upload](https://wiki.can-nx.com/en/guides/link-knx-file/), then reopen the selection.
- **Duplicate object numbers: …** or **The object number must be a whole number between 1 and 255**: correct the flagged cells. The floppy disk stays disabled until then.

For an unavailable button, an address that cannot be found or an uncertain result after saving, follow the [Crestron troubleshooting](https://wiki.can-nx.com/en/guides/link-crestron-help/). If the problem persists, contact support@can-nx.com.