OpenVario Protocol

This document describes the OpenVario communication protocol. Communication between sensord and variod and XCSoar is based on NMEA sentences. NMEA is the abbreviation for “National Marine Electronics Association”.

Version 1.3

The original definition of these sentences can be found here.

Version 1.3 14.03.2016 battery voltage sentence added


Generic definition:

$POV,<type>,<value>,<type>,<value>, .....*<Checksum>

The NMEA sentence always starts with $POV and ends up with a checksum and “*”. Each $POV sentence can contain multiple datapoints defined by type and value. The type part is a uppercase letter describing the type and meaning of the following value according to the overview of supported types below. The value is a floating point number. The length of the sentence is not fixed, but terminated with the usual asterisk and a two character checksum.



Value pair

The following value pair are defined at the moment:


  S: true airspeed in km/h
  Example: $POV,S,123.45*05


  P: static pressure in hPa
  Example: $POV,P,1018.35*39
  Q: dynamic pressure in Pa
  Example: $POV,Q,23.3*04
  R: total pressure in hPa
  Example: $POV,R,1025.17*35


  T: temperature in deg C
  Example: $POV,T,23.52*35


  V: battery voltage in V
  Example: $POV,V,11.99*31        


  E: TE vario in m/s
  Example: $POV,E,2.15*14


  C: Command followed by type of command and parameter if necessary
  Commands are grouped in "Types":
    VU: Volume of external vario up by 10%
    VD: Volume of external vario down by 10%
    VM: Mute external Vario
    Example: $POV,C,VU*09 => Set up volume by 10%
     Example: $POV,C,MC,+0.5*28 => Set McCready to +0.5
   Wing Load:
     <value> is a factor of the additional weight added by water ballast in relation to the reference weight of the glider
     Example: $POV,C,WL,1.0*12 => No water ballast
              $POV,C,WL,1.1*13 => 10% more weight than reference weight       
     <value> reflects the value of bugs
     Example: $POV,C,BU,1.0*1E => No Bugs
              $POV,C,WL,0.5*16 => 50% Bugs      
   Real Polar:
     RPO,<coff a>, <coff b>. <coff c>
     <coff x> are reflecting the coefficients of the polar including bugs and ballast
   Ideal Polar:
     IPO,<coff a>, <coff b>. <coff c>
     <coff x> are reflecting the coefficients of the ideal polar (just glider, without bugs and ballast)


The NMEA Checksum is calculated over the NMEA string between $ and *. The checksum is a hexadecimal number representing the XOR of all bytes

Navigate to Audio Vario / Speed to Fly

OpenVario as Device in XCSoar

The Openvario Flight Computer has to be selected as Device in XCSoar. The communication between OpenVario and XCSoar is based on TCP at Port 4352. This must be selected in the XCSoar Device-Manager accordingly. In contrast the communication between OpenVario and Flarm (or nearly all kind of IGC-equipment like loggers) is based on a serial port.

Edit the Device Settings in XCSoar Device Manager

XCSoar-Settings for the OpenVario

NMEA-Output, monitored in XCSoar Device-Manager

Navigate to Sensord

Navigate to Variod

Back to Software-Overview

Back to Setup Guide