> 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/ethernet-rov-locator/communicating-with-the-rovl/messages-from-host-to-rovl/nmea-format-messages-to-receiver.md).

# NMEA-Format Messages to Receiver

To accommodate third-party serial port forwarding software that requires messages to be in NMEA format, the ROVL receiver can optionally accept user commands in an NMEA carrier packet. The packet format is a dollar sign (‘$’), followed by five ***arbitrary*** characters, followed by a comma, followed by a user command (see next section), optionally followed by an asterisk, optionally followed by checksums or other characters (the receiver does not parse checksums; everything after the first asterisk is ignored). The following examples are all valid commands to print the configuration and menu, although they are not all valid NMEA sentences:

     $USTXT,?\*45

     $USTXT,?

     $USTXT,?\*

     $USTXT,?\*\*455

     $1au56,?\*2A