> For the complete documentation index, see [llms.txt](https://docs.ceruleansonar.com/c/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.ceruleansonar.com/c/ceruleantracker/overview/operating-ceruleantracker/input-device-configuration-panels/dvl-tab.md).

# DVL Tab

The DVL tab may have a “Force $DVEXT” button. This button is visible when the DVL can’t be found.  Use it when you know the DVL is attached to a serial port, and the $DVEXT message has been turned off in the DVL, and thus cannot be found either by searching serial ports or setting a specific baud rate. This button will send a message to each unallocated active serial port telling any DVL that may be attached to turn on its $DVEXT message. It has **no benefit** when the DVL is attached to the Ethernet. Note: this process may disturb other devices attached to your PC’s serial port that aren’t expecting to get this kind of message out of the blue. Note: if another serial device is also being searched for, it may interfere with this process, in which case you should wait until the other searches are finished (or turn off the other devices) and click this button again.

{% hint style="info" %}
Note: this process may disturb other devices attached to your PC’s serial port that aren’t expecting to get this kind of message out of the blue. 
{% endhint %}

{% hint style="info" %}
Note: if another serial device is also being searched for, it may interfere with this process, in which case you should wait until the other searches are finished (or turn off the other devices) and click this button again.
{% endhint %}

![DVL configuration tab](/files/cmIYjxzfrzwHZL9uFqAO)