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B737NG Overhead InterfaceIT I/O's POSTED!
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SWeker



Joined: 04 Mar 2004
Posts: 223
Location: Brooklin, Ontario, Canada

PostPosted: Sun Apr 08, 2007 8:30 pm    Post subject: B737NG Overhead InterfaceIT I/O's POSTED! Reply with quote

Evening,
At the time of writing this post, the files still may be 24 hours from being available for download, but they are all completed and functional!

I wanted to post a brief description of the methodology I used when programming the B737NG overhead (and MIP) switches. To save over 100 inputs Shocked .......YES, 100 inputs on your SYS board, I did not create an XML file for a switches OFF position.

You may remember a lengthy conversation about the methodology here (http://www.flightdecksolutions.com/forum/viewtopic.php?t=2783&highlight=), and I wanted to enhance that with a few pictures and ensure it is clear why I chose this route.

The basic theory is this.....InterfaceIT has the ability to perform numerous actions at one time. Therefore, to save inputs, I've programmed the XML files to recognizes a switch in the ON position and perform the necessary action. In addition, I've also programmed the same XML file to sense when a switch is NOT in the ON position, and instruct InterfaceIT to perform the opposite or OFF action.

Here's an example....
For the 'Wing Light' toggle switch, you can see that the XML file is required for the ON position, and NO XML file is required for the OFF position as the logic says, "if the B737NG-I-Winglight.xml file senses that the switch isn't in the ON position, it must be OFF"



More complex example......
Here I've used the Left Wiper rotary selector. The best way to think of a rotary selector is that it a switch with multiple ON's / OFF's. In this case, 3 XML files are required for Intermittent (ON state) / Low (ON state) / High (ON state). Again as outlined before, if InterfaceIT doesn't recognize any of these 3 ON states, it assumes the Left Wiper is in the "Park" or OFF position.




Hope this helps!
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neuman5022



Joined: 25 Nov 2005
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Location: Nelson NEW ZEALAND

PostPosted: Sat Apr 21, 2007 3:51 am    Post subject: Reply with quote

Hi Steve

Your logic looks fine, and it's really great we can save the I/Os we need so much.

I am far from being an expert in this field, but I have one question for you. If there is a situation where a switch in the "off" position needs to do something (for example the gear handle when "up" or "off" ) can your programing system tell the card: "when the gear handle is not "on" - light up the red LEDs "?

If the answer will be yes - I rest my case Very Happy

Cheers

Isaac
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SWeker



Joined: 04 Mar 2004
Posts: 223
Location: Brooklin, Ontario, Canada

PostPosted: Sat Apr 21, 2007 4:32 pm    Post subject: Reply with quote

The answer is a big 'YES'!

Even if you only wire up one state (ON or OFF), you can still program actions to both states. InterfaceIT is AWESOME for that type of stuff. In fact, you can literally attached an infinite number of actions for each state so not only will this allow for multiple things to occur, but the possibilities are also endless. Cheers, Steve
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SWeker



Joined: 04 Mar 2004
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Location: Brooklin, Ontario, Canada

PostPosted: Sat May 12, 2007 10:35 am    Post subject: ***UPDATE*** Reply with quote

PLEASE NOTE:
Peter outlined to me earlier this week that some of my logic was not correct for some 3 position 737NG toggle switches. In some cases I programmed the toggle switches as if they were OFF-ON-ON, rather than the standard ON-OFF-ON. Please note that new XMLs have been created to address the problem (version 1.1) and will be uploaded to the InterfaceIT server within the next day or two. Below are the affected functions and files....

New / Updated:
NoSmoke - On / NoSmoke - Off
Seatbelts - On / Seatbelts - Off
APU - Off / APU - Start
Strobe - Position (missed prior)
Pack1 - Off / Pack1 - High
Pack2 - Off / Pack2 - High
Isolation Valve - Open / Isolation Valve - Closed
Exit Lights - Off / Exit Lights - On

Will be deleted as they are not required:
B737NG-I-nosmoking_auto.xml
B737NG-I-seatbelts_auto.xml
B737NG-I-apustart_auto.xml
B737NG-I-pack1_auto.xml
B737NG-I-pack2_auto.xml
B737NG-I-isolationvalve_auto.xml
B737NG-I-emerexitstate_armed.xml
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Tomlin



Joined: 23 Aug 2004
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PostPosted: Wed Jul 18, 2007 1:12 pm    Post subject: Reply with quote

Steve,

Im glad I read this post. On the Lear 45 there are a few switches in the Light section that require Off-On-On, such as:

Off-Beacon-Beacon/Strobe

Off-Taxi-Landing

What kind of switch can I use for this? Im guessing it's a ON-OFF-ON swich and then you use InterfaceIT to tell the sim that ON is really 'OFF' for the OFF position, then OFF is really 'ON' for the Taxi light and that ON is really 'ON' for the Landing light, is that correct? I didnt realize that you can make a switch be the opposite of what it really is until I came back and read some of the posts in this thread. Thanks for your replies to all who can shed light.
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vidarf



Joined: 12 May 2006
Posts: 504
Location: Narvik, Norway

PostPosted: Wed Jul 18, 2007 2:40 pm    Post subject: Reply with quote

Simple:

There is NO connection between the physical switch' position or function and the software switch position or function.

Example:

In the PMSystems software for the boeing 737, there isd a three-way switch for the APU. The switch has three positions:
OFF
ON
(START)

When I write a position in backets, it is a momentary position. Meaning that if you press the switch to that position and release it, it will jump back to the previous position. In this example, the swich will jump back to ON.

A typical switch used for the APU switch has three positions:
ON
OFF
(ON)

And here's the goodie: InterfaceIT reads the switches. If it can't see a swich for a spesific position (for example position 1, 8, 34 and so on), it assumes the switch is in the OFF position. If the switch somehow is placed in any ON position, InterfaceIT will know that too. VERY neat - this way, you don't need to start your sim with all the switches in their correct "launch position".

Now to the clever part:

Forget the logical senses you might have. We're going to do something strange here!
The APU OFF position is connected to the ON position on the switch.
The APU ON position is connected to the OFF position on the swich.
The APU START position is connected to the (ON) position on the swich.

In other words: to start the APU, move the switch through OFF to (ON) and release to OFF. To turn the APU off, place the switch to ON.
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Tomlin



Joined: 23 Aug 2004
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PostPosted: Wed Jul 18, 2007 2:48 pm    Post subject: Reply with quote

I understand your 'strange logic' illustration, and thanks. Just to be sure though, Any double-throw switch will do for my application by what you are saying, correct?

Also, while we are at it, the local Radio Shack has 18 and 20 gauge wire. The 20 gauge will be fine, right, or is their another preference?

Regarding switches and their electrical rating, the lower, the better, correct?

Thanks,
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Learjet 45

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vidarf



Joined: 12 May 2006
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Location: Narvik, Norway

PostPosted: Wed Jul 18, 2007 2:58 pm    Post subject: Reply with quote

Any switches will do. You only need to assign the right function inside InterfaceIT to correspond with the switch' physical position - regardless of wether the switch is in an on or off position.

I don't know much about wire gauge, but we're talking about very small voltages here. I would suggest that you use the thinnest gauge, for two reasons: Too thick wires means larger resistance, and thin wires is easier to route between the switch and the SYS board.

Oh, and remember that you can daisy-chain eight switches at the black wire end - you don't need to run two wires to every switch. Example:

SW #1 is connected to the SYS board with one white and one black wire
SW #2 is connected to the SYS board with one white wire and to SW #1 with one black wire.
SW #3 is connected to the SYS board with one white wire and to SW #2 with one black wire.
SW #4 is connected to the SYS board with one white wire and to SW #3 with one black wire.
SW #5 is connected to the SYS board with one white wire and to SW #4 with one black wire.
SW #6 is connected to the SYS board with one white wire and to SW #5 with one black wire.
SW #7 is connected to the SYS board with one white wire and to SW #6 with one black wire.
SW #8 is connected to the SYS board with one white wire and to SW #7 with one black wire.

This goes for the annunciators too.


About the switches: My miniature switches are rated for 2A @ 250 VAC / 5A @ 125 VAC. WAY more than needed, but they work just fine.
Here's an image of one of my switches:
http://www.fagerjord.org/cockpit/img/thingys/switchcaps_parts_layout.jpg
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SWeker



Joined: 04 Mar 2004
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PostPosted: Wed Jul 18, 2007 6:26 pm    Post subject: Reply with quote

Evening Eric,

Quote:
Im guessing it's a ON-OFF-ON swich and then you use InterfaceIT to tell the sim that ON is really 'OFF' for the OFF position, then OFF is really 'ON' for the Taxi light and that ON is really 'ON' for the Landing light, is that correct?

You are 100% correct! Cool, glad to see folks are grasping it OK. Let me know you need help programming.

Quote:
the local Radio Shack has 18 and 20 gauge wire. The 20 gauge will be fine, right, or is their another preference?


With my original interfacing board, I used 18 gauge. DON'T DO IT! It was overkill. In fact, 22 gauge is better, especially with an overhead. Would recommend visiting a local electronic parts store as you'll get the wire MUCH cheaper.

Cheers, Steve
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A320East



Joined: 03 Nov 2006
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Location: Halifax, NS, Canada

PostPosted: Thu Jul 19, 2007 9:05 am    Post subject: Reply with quote

Guys,

Regarding wire guage for the Sys inputs and outputs 22g is just fine. A nice neat way to do your runs is by using ribbon cable like that used inside your computer for hard drives etc.

The Sys card is only reading a switch contact closure on the input side. Therefore, it makes no difference what rating your switches have as there is almost zero current being drawn through the switch and the voltage is all at logic levels, approx 5 volt max. In fact, you would be hard pressed to find a switch that would have "too low" a rating to use with the Sys card!

On the output side (LED's) there is still very little current flowing as the LED's are also being scanned just like the inputs, that is - they appear to our eye as being "on" but they are actually pulsing on and off thus saving power and reducing the total load current drawn from the USB that powers the Sys card. Again here - 22 guage wire is fine to use.

This was brilliant thinking and design by Brent and Peter!

The guage of a wire actually has little to do with it's resistance. All wire (conductor) has a given resistance per unit length but this only comes into effect when you are trying to move too much current through a conductor of any given size. When this happens the conductor heats up and the resistance goes up as well.
You can visualize this best by the following example: A lightbulb when read with an ohm meter will normally read as a short circuit as the filament is nothing more than a piece of tungsten wire. This being said wouldnt it make sense that when turned on it would blow a circuit breaker? Yes it would, save for the fact that when you do turn a lightbulb on the filament heats up and it's resistance increases greatly thus limiting the current that will flow through it. Light from a bulb is simply a by-product of the current flow as is the heat given off. The guage of the filament simply limits the amount of current that can flow - heavier filament = more curent = more light...

60 watt bulb at 120 volts draws .5 amps
100 watt bulb at 120 volts - .8333 amps
500 watt bulb at 120 volts - 4.16 amps
1000 watt bulb at 120 volts - 8.333 amps

Incandescent bulbs are extremely inefficient giving off mostly heat for the energy used. Flourescent and LED are much more efficient and produce accordingly much less heat in the process of producing light.

Max available wattage from a 120 volt 15 amp circuit - 1800 watts. Use this for figuring out how many computers (or anything) you can run off one AC circuit. Just read the wattage at 120 volts on the data plate of the computer power supply and add them together.

More than any of you ever wanted to know about wire and lightbulbs I'm guessing!

Happy wiring...
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Last edited by A320East on Thu Jul 19, 2007 9:12 am; edited 1 time in total
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Tomlin



Joined: 23 Aug 2004
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PostPosted: Thu Jul 19, 2007 9:11 am    Post subject: Reply with quote

Well, I was more worried (after talking to my Dad) that the toggles I was buying were rated for too HIGH a rating- in other words, they handle more power so they may not work as well with the very small voltages that the SYS cards are handling, understand?

Also, with the example of a OFF-ON-OFF switch being used to connect on the Lear45 for the OFF-Beacon-Beacon/Strobe LT switch, does the SYS/InterfaceIT software have the capability to combine an action on one switch? In other words, in my example above I have an OFF position, and then ON for just the Beacon, and then ON for the Beacon AND the Strobe together.
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pcos
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Joined: 03 Nov 2003
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PostPosted: Thu Jul 19, 2007 9:15 am    Post subject: Nope Reply with quote

Not an issue. Not at all.
The SYS boards are looking for open or closed circuits.
They are not measuring first Smile
Go play for awhile. This is all far easier than you think.. My bet...
Heck. I CAN do this .... The whole plan on these boards was for simplicity, off-the-shelf components etc... All the elements you are dealing with.
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A320East



Joined: 03 Nov 2006
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Location: Halifax, NS, Canada

PostPosted: Thu Jul 19, 2007 9:18 am    Post subject: Reply with quote

Eric,

Having too high a rating for a switch will never pose a problem in this case.

Since you can assign multiple actions to every switch position it is a snap to do what you want!

For the Beacon position tell the Sys card to turn on the Beacon

For the Beacon/Strobe position tell the card to turn on the Beacon, then add a second action telling it to turn on the Strobe.

Why, it's so easy a cave man could do it!
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Tomlin



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PostPosted: Thu Jul 19, 2007 9:20 am    Post subject: Reply with quote

"Go play for awhile"

Peter, that put a big smile on my face.

Thanks again!
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pcos
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PostPosted: Thu Jul 19, 2007 9:31 am    Post subject: For sure Reply with quote

Truly mean that... the unknown is daunting and once you start playing with these cards/software you will dig in and start doing more in -depth things for sure...
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