How to interface / What to choose


10. November 2014 by Peter

Some of the emails I receive from you guys are about how to get started with building a cockpit – more precisely how to get a switch to work in FSX.

First let me say that this posting only is based upon my own experience and knowledge. Others might find C++ programming easy, some might find SIOC impossible. Some might like Arduino. We all have different level of knowledge and skills. So do you homework and find what fits you before you embark this journey.

Okay, so it is a pretty simple question:  I have a switch and would like to make it work in FSX. What do I need to buy and how does it work?

Unfortunately the answer is very complex!!!

But to boil it down: The answer all depends on your software. Not the simulator it self but what simulated the aircraft systems. I use Prosim737. Other might use PMDG or iFly or something totally different. What you need to do is to find out what kind of hardware your choice in software supports.

Okay. So you have a computer with Flight Simulator running on it. And you have a switch. And you would like for a certain switch to work in FlightSim, when you push the switch in your home build cockpit. For this you need an interface card. The Interface-card lets you to connect a number of switches and then sends a signal (normally via USB) to your computer, that says something like: “Switch number 58 has been set to off”.

You then also need some software that translates “Switch #58” to “Seat Belt Off”; and this where it is important if you use ProSim737 or PMDG or something else. Because not all systems supports all types of cards. So do you home work. Research, research and then do some research. You are easily looking at a €100 bill, so better make it right the first time.

In the following I present three cards I have had experience with my self. Many of my emailers use PMDG, so I also try to relate the cards to PMDG. Prosim737 works natively with all three cards. The three cards I would like to mention are:

  • Leo Bodnar BU0836X
  • Pokeys 56U (Or 57E)
  • OpenCockpits MasterCard

They are all fairly priced and somewhat easy to work with. Each card works differently. Before you buy anything you must do your homework and google if a certain card can work with PMDG (if you use PMDG). I never tried PMDG in a cockpit environment; so I am not able to guide on that matter. But I am sure you can google some answers.

Let me run through my thoughts about the three cards I mentioned:

Leo Bodnar BU0836X (£ 50)

The Leo Bodnar BU0836X is a very easy card to use. It acts like an extra joystick in Windows/FSX with 36 buttons. So it is plug’n’play!

Via FSUIPC (Mouse Macro) you should be able to assign buttons to mouse clicks inside the simulator. Easy to use and with claps/clips on the card it is very easy to connect switches.

Reasonable price and no configuration is needed. However a major downside of the BU0836X is that I only handles inputs (switches). It can not light up a lamp/LED in the cockpit. But for switches it is a good card; and perhaps a good place to start!

Pokeys 56U (€ 50)

The Pokeys56U (or 57E if you but the ethernet-version instead of USB) is a wonderful card!

It gives you 56 inputs/outputs. So you can attach up to 56 switches or lamps/LEDs to each card. It does not have to be one thing or the other. So it is very versatile. Via the PoKeys software you can configure which ports are for inputs (Switches) and in which you have LEDs (outputs) installed. Very easy to work with. You can use the Pokeys with switches, LEDs and encoders. And with expansion cards you can add more LEDs or 7-segment displays.

But it does not act like an joystick in Windows. So you need some sort of software that allows it to speak with your simulator.

As I have not tried it with PMDG I do not know if this is possible. By a quick google search however it seems you are out of luck if you use PMDG. For ProSim737 however there is native support and is works wonderful!

It is a very versatile card and a very stable card. I only have one at this point and it is not installed in the sim. But if I was to rebuild my sim I would have used many more PoKeys cards. They are very good!

Wendy at has a wonderful site that aims the Pokeys card at cockpit building and explains what set-up to use to get things working. But you can also check, they also often offer free shipping.

The OpenCockpits MasterCard (€ 55 +VAT in EU)

Last contestant is the OpenCockpits series. It is a solution used by many builders. The cards are relatively cheap and offers many ports/slots for switches and LEDs.

OpenCockpits offer a whole range of different cards that also can control servo-engines, 7-segment displays, relays, act like a keyboard and much more.

The OpenCockpits cards “talks” with FSUIPC/FSX via a programmer language called “SIOC”. It is fairly easy to work with – once you manage the steep learning curve; but it takes time to program. However because it is a programmer language it also offers your with many options of programming things. As an example in my cockpit I have a engine starter switch that returns from GND to OFF once the engine is turned on. This is programmed via SIOC. So you should not be afraid of programming SIOC. It just takes time.

There is a program out there that enables SIOC and PMDG to talk together. So if you use PMDG you are off to a good start here.

Compared to the BU0836X you get many more possibilities with OpenCockpits cards. But you also get more homework. The OpenCockpits MasterCard gives you 72 inputs (Switches) and 38 outputs (LEDs) per card. So you only need a few before you have enough for the entire cockpit.

The downside about OpenCockpits (Apart from SIOC) is that the cards can be a bit unstable if they not get enough power via your USB port. When you connect the 4th or 5th card to a computer the cards starts acting a bit strange sometimes if the USB BUS on your motherboard not are able to handle it. I am not to decide if the motherboard to OpenCockpits cards are to blame. But you need to be aware of this when you also have a printer, and yoke and headset hooked up in the same computer. So not the most stable cards around.

The MasterCard it self does not have a USB-port. So In order to get a MasterCard to work you need to hook it up to an “OpenCockpits ExpansionCard” (+ € 38). The ExpansionCard connects to your computer via USB. So you need to buy both. But you can connect 4 MasterCards to 1 ExpansionCard.

The good thing about the OpenCockpits series (Apart that they are cheap) is that the series can handle almost everything is the cockpit. They also offer cards that can drive servos, relays and 7-segment displays. So once you get around SIOC you have everything working in one place. Further more there are many OpenCockpits users out there, so it is easy to get help and to share SIOC-scripts.

At this point my cockpits solely funds OpenCockpits cards. And apart few a few nags, my set-up is stable at this point. So they are good cards, but the learning curve is a bit steep.

Note that the prices in the OpenCockpits shop is without VAT. So if you are inside the EU you want to add 20% and so a MasterCard costs € 65. However if you are somewhat stable with a solder iron you can go for the no-warranty DIY set at € 25 and just safe you self a great deal of money.

So there you have it.

What to do… What to choose… 🙂

Well; if you just have started thinking about a cockpit and just want to make some switches work inside FSX; I would suggest you buy a BU0836X. You will get things working in no time and can have a lot of fun. You can use it with PMDG and you will also be able to use it later on.

On the other hand; if you at this point know that you are serious about building the whole darn thing you might as well start off with more complex cards. In this case the cards like Pokeys or OpenCockpits offers good value.

There are also better (and more expensive) cards like Polulu and Phidgets. But again make sure you are able to use with your software and that you have the now-how to make them work).

Again I must stress that you should do your research! Take a look at SIOC, see if you can understand it. Google your desired combination (Like “Pokeys Prosim737”).

Hope this was of help to you.


8 thoughts on “How to interface / What to choose

  1. Tristan says:

    Hi Peter,
    Thank you for your new posts. I have also been having trouble with Mastercards, but I have the kit (without a warranty). How have you fixed the problems you have born having?


    • Peter says:

      Hi Tristan.
      I have 3 DIY MasterCards. 2 work flawless and on the 3rd MasterCard 3 output pins are not working for some strange reason.
      I have had troubles with all my DIY cards. But it always turns out or be bad soldering. Re-soldering all connections have eliminated most of my problems. And of course make sure the IC’s are turns the right way.
      That should make them work.

  2. Yakov Kraus says:

    Hi Peter
    I follow your blog and learning a lot from you
    I moved from simple Leo Bonder cards to more complicated cards
    I used the SIMIOBOARDS from Hispapanels for my MCP
    It is the most economical solution and it is easy to use
    Look at my post

  3. AZWildk4t says:

    Hi Peter,

    My B737 includes 2 Leo Bodnar BU0836X and 2 Pokeys cards (one USB and one Ethernet). The Bodnar cards work flawlessly if you use LINDA ( These cards control my EFIS, and light switches and starter select on the Overhead panel. I use the Pokeys cards to control my MCP. There is little to no coding with these cards, which is why I didn’t use the I/O cards from Opencockpits. My 7-digit displays and PCB for them came from Wendy has been very helpful getting my MCP up and running.
    EDIT: Forgot to mention that you need FSSymphony if you use the Pokeys ethernet card.

    • AZWildk4t says:

      Forgot to mention that you need FSSymphony if you use the Pokeys ethernet card.

    • Peter says:

      It is great to hear how others use these cards.
      Can you elaborate a bit on your own set-up? Do you use PMDG, or?
      My experience is limited to Prosim737, with native support; so I know very little about how to link these cards with other products.

  4. I’m also want to build a radio panel; or connect some switches to my fsx (like a landing gear button), but are they some charts without 60connections? Like 10 or 5, that’s cheaper I think? I’ve search some on Ebay and stuff, and found these…..

    Greets Isaac

  5. isaaclego1 says:

    I’m also want to build a radio panel; or connect some buttons to my fsx; but are they some Ubs-boards whats not more then 10euro? Like 10 or 5connections…any idea? I’ve search on Ebay and other sites, but i’m only found these:

    Greets Isaac

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