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DPDT switch interfacing

 
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Tomlin



Joined: 23 Aug 2004
Posts: 1008

PostPosted: Mon Aug 06, 2007 9:31 pm    Post subject: DPDT switch interfacing Reply with quote

Okay, I really thought I had this one figured out after much fiddling, but not quite yet. I have a DPDT switch that is mechanically ON-OFF-ON and I am trying to implement it as the OFF-TAXI-TAXI/LANDING in the L45.

I have been told that it is in fact possible to have 1 switch activate multiple functions, such as the Taxi and Landing at the same time, or as in the case of OFF-BEACON-BEACON/STROBE.

I have fooled around quite a bit with tring these three methods:

Try to assign multiple functions (offsets) to one switch

Try to assign multiple bits to one switch

Try to wire 2 input wires to one switch (DPDT) with a common ground and a ground on both poles.

I have successfully gotten the switch to work as two different switches (as Beacon or Strobe, but not both).

What am I doing wrong here?
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Eric Tomlin
Learjet 45

Waycross, Ga (KAYS)
www.Hangar45.net
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bwr014



Joined: 10 Mar 2004
Posts: 1064
Location: Netherlands

PostPosted: Tue Aug 07, 2007 5:51 am    Post subject: Reply with quote

you have to assign the switch 2 times..

switch1= OFF Taxi + ON Taxi
switch2= ON Taxi + ON Land

I think it was something like that..

I have same idea with airbus seatbells/smoke..
it is OFF/AUTO/ON and i got that to work as well

Need 2 wires for this switch + ground

gr.

Frans M
frans@flightdecksolutions.com

example:
switch 1:
- <item displayname="FASTEN SEATBELLS OFF" key="0000050A01010100">
<description />
- <actions>
- <action displayname="Action 2 - Up / Off - Aircraft Simulation Technology" type="16" direction="0">
<data name="FASTEN SB AUTO" offset="17922" opp="setvalue" offsettype="1" data="82" sleep="-1" min="-1" max="-1" bit="0" />
</action>
- <action displayname="Action 3 - Down / On - Aircraft Simulation Technology" type="16" direction="1">
<data name="FASTEN SB OFF" offset="17922" opp="setvalue" offsettype="1" data="81" sleep="-1" min="-1" max="-1" bit="0" />
</action>
</actions>
Switch 2:
</item>
- <item displayname="FASTEN SEATBELLS ON" key="0000050A01010300">
<description />
- <actions>
- <action displayname="Action 3 - Up / Off - Aircraft Simulation Technology" type="16" direction="0">
<data name="FASTEN SB AUTO" offset="17922" opp="setvalue" offsettype="1" data="82" sleep="-1" min="-1" max="-1" bit="0" />
</action>
- <action displayname="Action 4 - Down / On - Aircraft Simulation Technology" type="16" direction="1">
<data name="FASTEN SB ON" offset="17922" opp="setvalue" offsettype="1" data="80" sleep="-1" min="-1" max="-1" bit="0" />
</action>
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www.airbus320.nl
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Tomlin



Joined: 23 Aug 2004
Posts: 1008

PostPosted: Tue Aug 07, 2007 7:24 am    Post subject: Reply with quote

Frans,

Thanks- I will try this. My only conern at this moment is that when I actually did get the SYS3 to see the one switch as two, was that it only saw the 1 and 3 positions, not the middle mechanical 'OFF' position, but since supposedly it doesnt matter, then Im guessing it was simply the way I had it wired.

Looking forward to giving it a go again
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Eric Tomlin
Learjet 45

Waycross, Ga (KAYS)
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vidarf



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

PostPosted: Tue Aug 07, 2007 12:22 pm    Post subject: Reply with quote

The OFF position is a position just like all others! Just assign the desired event to the OFF position, and you are good to go. Ignore the physical conditions of the switch. ON and OFF is two different states, both is recognized in InterfaceIT.
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Tomlin



Joined: 23 Aug 2004
Posts: 1008

PostPosted: Tue Aug 07, 2007 2:28 pm    Post subject: Reply with quote

I tried this at home during lunch and I successfully got the Beacon and Strobe to work simultaneously on one position, but not just the Beacon on the middle position. At this point I think it comes down to getting the wires in the right position maybe? Also, to do this would I need to put one function for 1 assignment on one pole and the other assignment on the other pole, or do they both stay on the same side? (that's how I have it wired now).
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Eric Tomlin
Learjet 45

Waycross, Ga (KAYS)
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Tomlin



Joined: 23 Aug 2004
Posts: 1008

PostPosted: Thu Aug 09, 2007 8:56 am    Post subject: Success and a Visual Guide on how to do this now available Reply with quote

Thanks to David C. Allen for his personal help, I now have a much better understanding of interfacing. As a result of his help and with his permission, I have posted a visual guide on how to wire for the functions on a DPDT switch and it's available here:
http://www.freewebs.com/flightlevel180/pcssoftwareinterfacing.htm

If you would just like to read the text portion, it follows:

*****
Position 1 = OFF
Position 2 = TAXI
Position 3 = TAXI/LANDING

Then looking at the switch continuity

Position 1 = On
Position 2 = Off
Position 3 = On

Then I look at how many inputs I need to use.
In this application you would need 2 inputs for a three position switch

Position 1 = Input 1 ON, Input 2 Off
Position 2 = Input 1 Off, Input 2 Off
Position 3 = Input 1 Off, Input 2 On

So the logic must be

If the Switch is in Position 1 On, Then Lights = OFF
If the Switch is in Position 2 Off, Then Lights = TAXI
If the Switch is in Position 3 On, Then Lights = TAXI/LANDING

Substituting inputs for switch positions

Input 1 ON, Input 2 Off = Then Lights = OFF
Input 1 Off, Input 2 Off = Then Lights = TAXI
Input 1 Off, Input 2 On = Then Lights = TAXI/LANDING

***** ***** Dont Forget***** *****

When switch 1 is OFF the TAXI light is ON! Reverse of normal thinking and when switch 2 is ON the Landing light is ON


If you look at it as two switches, this would be your logic

Switch 1
Input 1 ON, Then Lights = TAXI Light OFF
Input 1 OFF, Then Lights = TAXI On

Switch 2
Input 2 OFF = Then Lights = LANDING Light OFF
Input 2 ON = Then Lights = LANDING Light ON

If Switch 1 is OFF Taxi light is on
If Switch 1 is on Taxi Light is OFF

IF Switch 2 is OFF Landing Light is OFF
If switch 2 is ON then landing light is ON

You should be able to test it with two switches and the two inputs, then just move the wires to the DPDT Switch
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Eric Tomlin
Learjet 45

Waycross, Ga (KAYS)
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