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Mission Statement 

The purpose of FLAPS-2-APPROACH is two-fold:  To document the construction of a Boeing 737 flight simulator, and to act as a platform to share aviation-related articles pertaining to the Boeing 737; thereby, providing a source of inspiration and reference to like-minded individuals.

I am not a professional journalist.  Writing for a cross section of readers from differing cultures and languages with varying degrees of technical ability, can at times be challenging. I hope there are not too many spelling and grammatical mistakes.


Note:   I have NO affiliation with ANY manufacturer or reseller.  All reviews and content are 'frank and fearless' - I tell it as I see it.  Do not complain if you do not like what you read.

I use the words 'modules & panels' and 'CDU & FMC' interchangeably.  The definition of the acronym 'OEM' is Original Equipment Manufacturer (aka real aicraft part).


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Journal Archive (Newest First)

Entries in Phidget Cards (2)


Using Interface Cards and Canon Plugs To Convert OEM B737 Parts 

There is little argument that real aircraft parts add a level of realism and immersion to the flight simulator experience.  Furthermore, real parts (Original Equipment Manufacture/OEM) are built to last and if converted correctly will provide many years of trouble-free operation and enjoyment.

LEFT:  Although not the most complicated module, the wiring inside the audio control panel is a good example showing the clean-cut wiring and workmanship.

For the uninitiated, conversion of OEM parts can appear problematic.  Where does one begin to convert an aircraft part for simulator use?  

This post will attempt to explain the basics behind converting and connecting an OEM module via an interface card and Canon plug to Flight Simulator using ProSim737.   Additionally, it will introduce and provide a general overview of Phidget Manager 21 (PM-21) software.

Please note, I am not an expert on electronics.  My background is Earth Science (geology) which is far removed from electronics...  Like others, I have learnt how things are done by 'trial and error' and listening to those more knowledgable than myself in this field.

OEM Parts - Modules and Panels

The first thing you will notice about an OEM part (module/panel) is the build, feel and appearance is much better than a reproduction part.  It is at this stage you will be thinking ‘I don’t really want to destroy the part by opening it and rewiring everything’.  The good news is that, while some parts certainly do need rewiring, many do not.

Fortunately, many OEM parts are converted along similar lines to another.  Granted the pin outs and wiring are different between units, but the methodology used to determine the pin outs and wiring is identical.  It’s a matter of replicating your methodology with each part.

Canon Plugs - The Interface to a Wiring Maze

If you look inside a OEM module you will be surprised at the multitude of multicolored wires that connect to various relays, switches, solenoids and circuitry. Moreover you will be very impressed with the neatness and integrity of the wiring harness and as mentioned earlier, you will be loath to destroy the craftsmanship employed.

LEFT:  Twin Canon plugs belonging to a B737 AFDS unit.  The plug on the right is OEM while the left plug needed some alteration.

In the real aircraft, a module is connected to the aircraft’s wiring harness by a Canon plug which is a plug with any number of pins; each pin corresponding to particular function.  A Canon plug can be locked in place with the clockwise turn of the locking cap providing a solid yet removeable connection.

The benefit of Canon plugs, amongst others, is that they provide an easy and solid connection to the module’s internal wiring.    Many individuals remove these plugs, pull apart the module and gut the wiring starting afresh.  While this certainly is possible, why do it when all that is required is to ascertain the pin-outs of the Canon plug to connect to the pre-existing wiring inside the module.  I doubt many of us, with the exception of a professional electrical craftsman, have the ability to duplicate the quality of workmanship seen in an OEM module.

Unfortunately, it is common place to find modules that are sold without the corresponding male or female side of the plug.  In this case the correct male or female plug must be bought separately, an existing plug converted, or a new plug fabricated.  If you have the opportunity to use a Canon plug, always try to use it before cutting the plug from the unit.  

Determining Pin outs - The Value of a Good Multimeter

The crux of converting an OEM module is to understand the functionality of the module in question.  The best place to begin learning how a module operates is the latest FCOM.  OEM modules are made for real aircraft and as such often have functions that may not be incorporated into flight simulator.  After arming yourself with 'operator knowledge', the next step is to decipher the often cryptic maze of pins in the Canon plug.  Once this is understood, the conversion is relatively straightforward with the addition of an interface card and power supply (if needed).

LEFT:  Twin Canon plugs showing the snake-like pattern of pin location and numbering.  This module uses two Canon plugs marked J1 and J2 (click to enlarge image).

The pins of a Canon plug will provide at the minimum: functionality for the part, an earth (common) and a pin (s) dedicated to power.  Traditionally, all modules have used incandescent bulbs for backlighting which is powered by 5 Volts.  Depending upon functionality, some modules require different voltages with 28 Volts being the norm.

It’s important to be able to decipher which pin does what to ensure correct functionality within Flight Simulator.  This involves logical thinking and little bit of trial and error.  It is a high probability that not all the pins in the Canon plug will be used or needed in Flight Simulator.  Remember, that in a real aircraft there are multiple systems and some wires and pins will connect with these 'unneeded' systems.  

If you carefully study the pin layout in a Canon plug you will note it is not random – there is a definite order in how the pins are presented.  You will note that in all probability some pins are numbered, but not all.  The numbers move sequentially so the pin beside the pin marked ‘5’ will either be pin ‘4’or pin ‘3’.  The snake-like pattern printed on the inside of the plug is there for good reason - it acts as map guiding you from the highest number to the lowest.

By far the easiest way to determine pin outs for functionality and power, if you do not have a wiring schematic, is to use a multimeter set to conductivity mode (beep mode).  Please read my post in which I explain in detail how to use this tool in conductivity mode - Flight Deck Builders Toolbox - Multimeter.  

Which Interface Card

Most parts require an interface card of some type to allow communication between the part and flight simulator.  There are several cards that, depending upon the part’s functionality, can be used: Leo Bodnar joystick cards and PoKeys cards are commonly used while Phidget cards have been the mainstay for quite a few years.  Flight Deck Solutions also produce some excellent system cards while Polulu is another manufacturer.

LEFT:  Phidget card (one of several types).  By far the most popular, Phidgets often used in conversion work are the 0/0/4, 0/16/16, analogue and servo cards.

Which interface card is used will depend on the functionality of the module.  A simple on/off switch or a rotary knob can be interfaced using a PoKeys, Leo Bodnar Joystick or another similar 'button-type' card.  If you have a lever that needs calibration then a potentiometer will be needed.  The Leo Bodnar card is an excellent choice and will automatically register the potentiometer’s movement as an axis when the card is activated in Windows.  A light indication (korry), or a more complicated module may require a card such as Phidget 0/16/16 or 0/0/4 card.  Throttle automation and motor activation will need additional cards such as a Phidget Advanced Servo card or Polulu card.

Phidget Cards

Phidget cards, or Phidgets, have been around for a considerable time and have been the mainstay for enthusiasts wishing to control robots, cars, airplanes and the like.  Phidgets produce several cards; however, the core cards used in flight simulation are the Phidget advanced servo cards, 0/16/16, 0/0/8 and 0/0/4 cards.  To read more about these Phidget cards, navigate to the their website and enter the card type into the search bar.

What Does the Interface Card Do?

The interface card is placed between the computer and the OEM module and the wires from the Canon plug are fed directly to the card (power wires usually do not connect with the card).  The card provides you with three things: an input, an output and a USB connection to the computer (or a powered hub that is then connected to the computer). Once connected, the card acts as an interface which converts an inbound analogue signal (For example, the upwards or downwards ‘throw’ of a switch) to an outgoing digital signal. For every analogue input there will be a corresponding digital output. 

An interface card requires software/logic which either comes with the card (embedded) or is downloaded from the developer’s website.  Some cards utilize Windows and the process of plugging the card into the computer will initialize the card allowing the embedded software of the card to be viewed from in Windows.  The software is found by opening the  joystick controllers menu - type ‘joy’ into the search tab of the computer to be directed to this joystick wizard. 

An example of a card that has embedded software and comes pre-calibrated is the Leo Bodnar Joystick card.  The 'Leo' card uses the joystick controller menu in Windows to allow access to the card logic. Other cards such as Polulu require calibration and programming in their own software and without calibration and programming will appear unresponsive when first connected to a computer.  Phidget cards utilize their own software (Phidget Manager 21) downloadable from the Phidgets website.

If using multiple cards of the same make and type, each card will be assigned a dedicated number allowing you to know which card controls what module.

To connect a function (for example a switch) to the Interface card you run the wire from the Canon plug/terminal to the input terminal on the card.  This process is replicated for each function of the module, bearing in mind that some functions on the Captain and First Officer side may be duplicated.  If this is the case, the wires from the module are connected into the same input terminal on the card. 

If power is required to operate the module's function or for backlighting of the panel, then a wire from the power supply will need to be connected to the correct pin in the Canon plug of the OEM module.  The usual method is to connect  power from the power supply to a solid high amperage terminal block and then to the OEM module.  Power is not normally connected directly to an interface card, unless the card has this particular capability. 

The connection of the wires to the card and connection of the card to the computer provides the link to enable the various inputs and outputs to be read either by standalone software, Windows, or directly in ProSim737.

Phidget Manager 21 (PM-21) - The Bare-shell Basics

PM-21 is the replacement for the older styled Phidget’s Library.

LEFT:  Opening screen of the PM-21.  Each serial number is specific to an individual card.  This is the number you allocate in the  dropdown menu when configuring the output in ProSim737 (click to enlarge).

Phidget Manager 21 (PM-21) software when installed to your computer generates a list indicating which Phidget cards are currently connected to the computer.  Each connected Phidget card can be opened individually from this list. Selecting a card will open a sub-window providing set-up information and the inputs and outputs for the selected Phidget card. 

There is also a testing area to check the functionality (inputs & outputs) of the module in addition to several other specialist features.

It is a little difficult to explain, but when this screen is open you can as in the above example, manipulate the switch up or downwards and a corresponding tick (check mark) will be seen in the input.  PM-21 will then assign this item (switch) to a dedicated output number specific only to this card.  The output number is what is used when configuring the device in ProSim737.

If converting an indicator (light) or mechanically-produced sound, the software can be used to determine if the indicator has been wired correctly.  Selecting the input section and placing a tick (check) into the appropriate box will cause the indicator to illuminate or the sound to become audible.

LEFT: PM-21 sub menu open for Phidget 0/16/16 card that controls fire suppression panel.  Moving a switch on the hardware will show a corresponding tick in the input section.  The output section can be used to test the hardware to ensure the function is working correctly (click to enlarge).

It is important to remember that the  Phidgets 21 Manager can only read installed cards if ProSim737 is closed (as of ProSim737 Version 1:34).  If the ProSim737 main menu is open, PM-21 cannot obtain the necessary information to read the card correctly.

Configuring the Interface Card in ProSim737

Once the wires from the module have been connected to the inputs of the interface card and inspected (in PM-21, Windows, or whatever software) for correct connection, the output from the interface card must be configured in ProSim737.

Before proceeding further, it is important to determine if the cards you are using are being read by ProSim737.  Open the main ProSim737 menu and select configuration/drivers and confirm that each box corresponding to the card type installed has been checked/ticked.  After this has been verified, the main ProSim737 screen will indicate which cards ProSim737 is reading.  This is a handy way to know if your interface cards are connecting correctly to your computer and are being correctly read by ProSim737.

The process to configure an output is addressed in the ProSim737 manual.  Therefore, the following is an overview.

To configure an output:

1.   Select the appropriate tab in the configuration menu (configuration/switches, configuration/indicators, etc.) that corresponds to the function of the module (i.e. light test switch)  
2.    Scroll down through the list to find the correct function (i.e. light test switch)
3.    Move the switch on the module noting the input/output variables at the top of the computer screen
4.   From the dropdown box beside the function, select the correct interface card type and serial number. (Another method is to press A located beside the function.  This will automatically select the last known position of the switch and automatically assign it).
5.    Beside the interface card dropdown menu, there is another dropdown menu.  Select this menu and select the correct digital output (variable shown on the screen when the switch was moved)

A similar method can be used for indicators.

Once this is done, close and reopen the ProSim737 main menu.  The function should now be registered in ProSim737. Although this process sounds rather convoluted, once done a few times it becomes second nature.


This is a very simple introduction to the conversion of OEM parts using the Canon plug system and the use of interface cards, in particular Phidget cards and the use of Phidget Manager 21 software. 

In general, PoKeys, Leo Bodnar joystick cards and Phidget cards (type 0/16/16 and 0/0/4) will cover the interfacing of many functions used in real aircraft modules.  However, not every part is as easy as a switch to convert.  Depending upon the complexity of the module, there may be multiple pin outs that need to be deciphered, additional logic needed, and the requirement to use multiple or single interface and/or relay cards before the part will successfully connect with Flight Simulator.

Acronyms and Glossary

Canon Plug – A plug made by Canon that allows a secure link between wiring systems.  The plug incorporates any number of pins, each pin corresponding to a particular functionality.  Many Boeing modules incorporate one, two, three or four Canon plugs depending upon the degree of sophistication in the module.
Module or Panel – Boeing parts are often called modules or panels (I use both words interchangeably)
OEM – Original Aircraft Manufacture (real aviation part).
Phidget Manager 21 (PM-21) – Software supplied by Phidgets that provides the logic behind the various Phidget interface cards.


Powering, Wiring & Configuring the B737 Throttle Quadrant

The picture shows the front of the throttle quadrant with the attached 0064 and 0066 phidget cards and the BUO 836X Leo Bodnar card.  I thought this to be the best location for attaching the cards rather than having them either sit loose or be mounted on a separate board.  The wiring and cards will not be visible when the quadrant is sealed against the front of the main instrument panel (MIP). However, if servicing is required, access to the cards and wiring can easily be achieved via the front of the MIP.

LEFT:  Front of Throttle quadrant showing wiring and card installation.

The Phidget cards are required to provide functionality to the trim indicator, motorizing of the trim wheels (via a servo motor), and to allow the deployment of the auto speed brake.

Different Voltages Required

The throttle quadrant requires different voltages to operate correctly.  Apart from the obvious USB power through the USB cable connected to the cards, external power is supplied via a standard style computer power source, rated to 400 watts.  To reduce the main power, which is 240 volts in Australia, to that required by the phidget cards and integrated back lighting (IBL); I installed a benchtop power board kit.  This small kit comes unassembled in a box direct from China.  Assembling the kit and card isn’t difficult but it does taken considerable time to solder all the terminals in place.  The benchtop kit allows the power from the computer power source box  to be reduced to: 3.3 V, 5 V, +12 V and -12V.  Each power selection is protected by a 5 amp in-line fuse.  In an attempt to try and maintain neatness I mounted this card directly to the power source box. 

Functions on the throttle quadrant that require power are:

  • Integrated back lighting (IBL – aircraft bulbs) – 5 volts
  • Main parking brake light – 12 volts
  • Fire suppression module backlights and handle lights – 5 volts
  • Speed brake servo.  Phidget controlled servo motor - 5 volts & 12 volts
  • Trim wheels (spin when electric trim is activated from yoke) Phidget controlled servo motor – 12 volts
  • Lighting on/off switch (TQ IBL only) – 5 volts
  • Hobbs meter (to indicate length of time TQ has been operational) – 24 volts (12V + 12V)

The other avionics that will be installed into the avionics bay are powered directly via USB (unless real aircraft modules are used)

I wasn’t exactly sure what the amperage draw was from the servo motor (that spins the trim wheels and activates the speed brake).  Therefore, to connect the external power through the benchtop power kit, I decided to use 10 amp wire. I have a sneaky suspicion that 10 amp rated wire is overkill for the task, but at least I know it won’t melt.

If you want to view more detailed images, please navigate to the image gallery and select construction

Phidget & Leo Bodnar Card Programming

Most of the buttons and levers located on the throttle are assignable to standard FS controls through the windows joystick controller (or Leo Bodnar card).  But, those throttle functions that are controlled by a Phidget card, initially require mapping through a registered version of FSUPIC, so that they can be seen within the Phidget's interface to allow assignment and configuration.  I used a FSUPIC profile to map the functions controlled by Phidget cards, which were: the trim indicators, trim wheels and speed brake. 

I'll be the first to admit that my knowledge of Phidgets is lacking; Until recently I couldn't spell the word.  With the help of a very kind person from northern California who is exceptionally knowledgeable on Phidgets my worries were soon overturned - at least for the time being.  During a two hour telephone hook-up, the correct computer drivers and Phidget libraries were installed on the computer and the attached Phidget cards on the TQ were programmed to the required throttle quadrant fields with various FS variances and offsets (after they were mapped in FSUPIC). 

As with many software related products, there was a bit of troubleshooting and configuration that needed to be done, but nothing too drastically complicated.  It all seems quite easy when you know how.

The throttle now has full functionality with the exception of the automatic deployment of the speed brake on flare and touch down.  This requires an additional Phidget card (004 card) which has four relays that can be computer controlled.  The relay is needed to activate the squat switch to turn off the servo motor allowing the speed brake to deploy.  This additional Phidget card will be installed shortly.

It was quite amusing when we programmed the Phidgets to the trim wheel movement.  I hadn't expected the movement and was leaning on the trim wheel while discussing the issue on the phone.  BANG WHIRL as the trim wheel began to spin at a high number of revolutions.  The movement and noise startled me and I almost fell from my perch!  The TQ shook madly as the trim wheel rotated (as it isn't yet screwed to a platform) - I can now understand how real world pilots spill their coffee!

LEFT:  Phidget 1064 card attached to recess panel on front of TQ.

Programming the Leo Bodnar card was straightforward; this card follows the standard for windows joystick controllers.  Basically, you just follow the screen prompts and allocate button functions to whatever devices you choose.

One aspect that required careful attention is to check that the FS controls are not duplicated in either the  phidgets, Leo Bodnar, yoke, or other joystick controller settings.  duplicate settings will cause problems.

Throttle Functionality Includes:

  • Independent forward and reverse thrust to engine 1/2 throttles
  • Speed brake arming
  • Speed brake flight deployment (spoilers)
  • Speed brake deployment on flare & touch down (requires another Phidget card)
  • Trim wheel rotation/revolution when trim applied
  • Trim wheel indicator functional and moving when electric trim is activated from yoke
  • Park brake and light
  • Cut off Levers (fuel idle & cutoff)
  • Flaps
  • TO/GA button functional (to go around)
  • A/T disengage functional (auto throttle)
  • All IBL backlighting functional

The stab trim switches I have had wired in such a way to stop the trim wheels from spinning.  Although the spinning trim wheels are accurate to the real aircraft, they can be annoyingly noisy, especially at night when others are trying to sleep.  To disengage the trim wheel motor from the spinning trim wheels,  I flick the stab trim switch.  To activate the them again, I reverse the process.

The horn cut out switch is currently not connected to throttle functionality, however, can be allocated to another FS function if required.

Fire Suppression Module (FSM)

A communication error with my friend, who was converting this modue to FS use, means a little more work is required to add FS functionality.  At the moment I have power running to the handles causing the lamps to be lit all the time, and some of the module buttons to be back lit.  To my knowledge, the handles should only light when the backlighting is switched on or when they are activated.  I still have the original Boeing circuit boards and solinoid switches, and athough I haven't given the matter a lot of thought, I believe that it should be possible to connect a Phidget 004 card, which has relays, to allow activation of APU and fire handles via the original solinoid switches.  I'm not quite sure on how to activate the buttons and switches - perhaps FS offsets and phidget software.  Rome wasn't built in day, so more on this later.

Link to Phidget cards

Link to Leo Bodnar cards