L-1011 Avionics Bending: SFENA HSI and ARINC 429 - Part 5

So now that we have walked through the major function blocks of the SFENA HSI it is time to think about integrating it with a flight simulator. For this device I will use X-Plane 10 by Laminar Research. As you probably know, the X-Plane platform can output data in a number of ways. Perhaps the easiest way is to simply let the software stream some data via UDP to another computer that the HSI is attached to. However, I will use a different method that will use a X-Plane plugin written in C that will offload the work of sending the data to the HSI to an external device driver ... therefor, keeping the computational demand on X-Plane as minimal as possible while preserving the maximum frame rate.

In particular we will be using at the following data points:

X-Plane 10 Screen Shot of Data Sources

In order to get to all of the parameters I need I will use the SDK for X-Plane and stream the data via the data references (aka. datarefs) exposed by the SDK. So, lets match up some SFENA HSI ARINC 429 labels with X-Plane 10 datarefs (the previous link is valid as of the time of the posting, however over time it might expire and/or change).

ARINC 429 Label: 320    
Function:  Magnetic Heading    
Dataref: sim/cockpit2/gauges/indicators/heading_electric_deg_mag_pilot

ARINC 429 Label: 321
Function: Drift
Dataref: sim/cockpit/gyros/dg_drift_ele_deg

ARINC 429 Label: 012
Function: Ground Speed IRS/AHRS
Dataref: sim/flightmodel/position/groundspeed

ARINC 429 Label: 101
Function: Heading Select
Dataref: sim/cockpit2/autopilot/heading_dial_deg_mag_pilot

ARINC 429 Label: 162
Function: ADF 1 Bearing
Dataref: sim/cockpit2/radios/indicators/adf1_relative_bearing_deg
and/or
Dataref: sim/cockpit2/radios/indicators/adf2_relative_bearing_deg

ARINC 429 Label: 222
Function: Omnibearing
Dataref: sim/cockpit2/radios/actuators/nav1_obs_deg_mag_pilot

ARINC 429 Label: 100
Function: Selected Radial
Dataref: sim/cockpit2/radios/actuators/nav1_course_deg_mag_pilot

ARINC 429 Label: 173
Function: Localizer
Dataref: sim/cockpit2/radios/actuators/nav1_course_deg_mag_pilot

ARINC 429 Label: 174

Function: Glide slope

Dataref: sim/cockpit2/radios/indicators/nav1_vdef_dots_pilot

There are additional labels to follow in the next posting. The HSI will also need a number of discrete lines that need to be switch by X-Plane via a 24V relay.