144 lines
4.4 KiB
Io
144 lines
4.4 KiB
Io
This document describes how to invoke FlightGear's generic IO subsystem.
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FlightGear has a fairly flexible generic IO subsystem that allows you
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to "speak" any supported protocol over any supported medium. The IO
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options are configured at runtime via command line options. You can
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specify multiple entries if you like, one per command line option.
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The general form of the command line option is as follows:
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--protocol=medium,direction,hz,medium_options,...
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protocol = { native, nmea, garmin, fgfs, rul, pve, ray, etc. }
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medium = { serial, socket, file, etc. }
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direction = { in, out, bi }
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hz = number of times to process channel per second (floating
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point values are ok.
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Generic Communication:
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--generic=params
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With this option it is possible to output a pre-configured
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ASCII string using a predefined separator. The configuration is
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defined in an XML file located in the Protocol directory of
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the base package.
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params can be:
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serial port communication: serial,dir,hz,device,baud,protocol
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socket communication: socket,dir,hz,machine,port,style,protocol
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i/o to a file: file,dir,hz,filename,protocol[,repeat]
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See README.protocol for how to define a generic protocol.
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Serial Port Communication:
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--nmea=serial,dir,hz,device,baud
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device = OS device name of serial line to be open()'ed
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baud = {300, 1200, 2400, ..., 230400}
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example to pretend we are a real gps and output to a moving map application:
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--nmea=serial,out,0.5,COM1,4800
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Note that for unix variants you might use a device name like "/dev/ttyS0"
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Socket Communication:
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--native=socket,dir,hz,machine,port,style
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machine = machine name or ip address if client (leave empty if server)
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port = port, leave empty to let system choose
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style = tcp or udp
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example to slave one copy of fgfs to another
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fgfs1: --native=socket,out,30,fgfs2,5500,udp
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fgfs2: --native=socket,in,30,,5500,udp --fdm=external
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This instructs the first copy of fgfs to send UDP packets in the
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native format to a machine called fgfs2 on port 5500.
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The second copy of fgfs will accept UDP packets (from anywhere) on
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port 5500. Note the additional --fdm=external option. This tells
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the second copy of fgfs to not run the normal flight model, but
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instead set the FDM values based on an external source (the
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network in this case.)
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File I/O:
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--garmin=file,dir,hz,filename
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filename = file system file name
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example to record a flight path at 10 hz:
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--native=file,out,10,flight1.fgfs
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example to replay your flight
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--native=file,in,10,flight1.fgfs --fdm=external
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You can make the replay from a file loop back to the beginning
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when it reaches the end of the file with the "repeat" flag:
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--generic=file,in,20,flight.out,playback,repeat
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Moving Map Example:
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Per Liedman has developed a moving map program called Atlas
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(atlas.sourceforge.net) The initial inspiration and much code came
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from Alexei Novikov.
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The moving map supports NMEA format input either via network or
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via serial port. Either way will work, but this example
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demonstrates the use of a socket connection.
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Start up fgfs with:
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fgfs --nmea=socket,out,0.5,atas-host-name,5500,udp
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Start up the Atlas program with:
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Atlas --udp=5500 --fgroot=path-to-fg-root --glutfonts
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Once both programs are running, the Atlas program should display
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your current location. Atlas is a really nifty program with many
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neat options such as the ability to generate and use background
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bitmaps that show the terrain, cities, lakes, oceans, rivers, etc.
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HTTP Server Example
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You can now interact with a running copy of FlightGear using your
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web browser. You can view all the key internal variables and even
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change the ones that are writable. If you have support in your
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favorite [scripting] language for interacting with an http server,
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you should be able to use this as a mechanism to interface your
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script with FlightGear.
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Start up fgfs with the --httpd=<port#> option:
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For example:
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fgfs --httpd=5500
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Now point your web browser to:
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http://host.domain.name:5500/
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When a value is displayed, you can click on it to bring up a form
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to assign it a new value.
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ACMS flight data recorder playback
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fgfs --fdm=acms --generic=file,in,1,<path_to_replay_file>,acms
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