My ARINC429 GPS does not show traffic on the map page

Many systems only display traffic on the map page if a heading data source is connected.

If you do not have such a data source (e.g. AHRS) in the aircraft, you can use AIR Traffic (AT-1/AT-2) to transmit the GPS track as a "heading" via ARINC429 (pseudo heading). 

This can be done using the following setting, either on the configuration web page of the AT-1/AT-2 (in expert mode, the PIN CODE 3000 must be entered) or via the configuration file: 

# TITLE: ARINC429 Send Heading
# DESC: Some ARINC429 systems displaying traffic do require heading data in order
# DESC: to display traffic correctly on their moving-map screens. If this option
# DESC: is activated, AT-1 transmits a GPS-track-derived aircraft heading over the
# DESC: ARINC429 data output. Under circumstances, for example, when the own
# DESC: aircraft is not moving, this heading data is inaccurate or even wrong. Be
# DESC: very careful! Heading data may be used for displaying traffic data from
# DESC: AT-1 only. Do not activate this feature if you are unsure of where the
# DESC: heading data is used.
# VALUES: ON, OFF
# DEFAULT: OFF
A429SENDHDG=ON 

Please note that, depending on the use of the aircraft and the configuration of your systems, it may not be permissible to use the GPS track as a heading. Before changing the settings, please clarify whether this is possible/advisable/legal in your aircraft.