Note that this applies only to the newer versions of the R2Sonic sonar that do not use the Reson 81xx compatible data format.
Start Isis and go to File>Record Setup>Sonar Setup and choose R2Sonic:

Check the boxes as shown if Snippets are to be logged - if these settings are not made then only bathy will will be logged to the XTF file. Click OK

In the Selecet Sonar dialog click the Advanced button:

Check the box shown to improve the performance of Isis in Realtime Mode. Hit OK OK until the Isis main window is displayed.
Click the Red Record button in Isis to launch the R2Sonic server and connect to the sonar, the R2Sonic server will launch:

Enter the correct IP address for your system and the Sonar Baseport as set in the R2Sonic sonar.
Check the ON-LINE box to have the Sonar connect to Isis and start displaying the data,
Use the Switch > Switch Now button in Isis to write the data to an XTF file.
Appearance of the default windows in Isis for an R2Sonic sonar with snippets:
