Shared Memory bit "solenoidStatus"
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Does exist a description of the information given by the different bits in the shared memory? I took a look on the technical manual but I could not find much.
I am building a landing gear box and I need to know what bit to use. “Gear solenoid” sound like the best candidate, but we have also “MLGWOW”.
Thanks!
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@Tulkas explore the header (.h) code you will surely find stuff in there that can help you (usually coders try to leave a lof of comments)
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Check out FlightData.h in your BMS directory -> Tools -> SharedMem.
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Thanks! That helped me to find it.
But I don’t know if I can get more information, would the solenoid be powered when the gear is down so permission button is no needed to retract?
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I don’t think this is exposed logic…
We don’t even model the button on the gear lever…
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That I know and it is fine, the consent button does not need to come from BMS because, well, if you are pushing the physical button that’s sending it’s own signal.
What I need from BMS is a signal that there is WOW, so the solenoid is unpowered and the gear level is locked in position, but also a signal that the gear is down and the plane is airborne (no WOW), so the solenoid is powered and the lever unlocked.
I suspect that “SolenoidStatus” may do that, but I need to know before I wire my LG box.
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@Tulkas Maybe @Marvin157th has an idea…
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You can grab Lightning’s shared memory viewer here. Together with the comments in the header file (the .h file), it really helps when figuring out the exact working of each value.
SolenoidStatus goes on/true when the gear handle is permitted to move.
You can get WOW separately too, if you need it, but for the solenoid it shouldn’t be necessary.
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Bit OT but with the real jet is it possible to move the gear handle to up on the ground and the WoW switch stops the retraction from happening until the wheels lift off? Or does WoW stop the gear handle movement itself?
My dad has told me of particularly brave pilots back in the day in other types selecting gear up before the takeoff roll so the gear retract as soon as they are airborne once the weight on wheels switch is released.
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@Tulkas – you gotta read the whole flightData.h
Look for MLGWOW and NLGWOW in LightBits3 - those are the weight on wheels predicates. There is only one for both mains, that’s deliberate.
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Cheers,Mark.
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The DN LOCK REL button, which is implemented in 4.35 is a mechanical bypass of the landing gear
handle solenoid. The solenoid prevents the handle to be moved inadvertently but may fail. The
mechanical bypass is then used to move the handle. Please note, these two actions do not have to
happen simultaneously. A Sim delay was introduced to allow the pilot to perform both actions
subsequently rather than simultaneously for obvious mouse and keystroke issues the real pilots (or
cockpit builders) don’t have to take into account.
On the ground, once WOW is activated, the landing gear cannot be retracted unless this safety button
is depressed. In the air, this button allows lowering the handle in case of a solenoid failure.
The WOW switch (Weight On Wheels) is implemented. Once weight is on the gear struts the WOW
switch is activated allowing or terminating various system functions. One of these functions is the lock
of the gear handle in the down position. This protection can be overridden by the DN LOCK REL
button as the name implies. Use with … caution -
@SOBO-87 IIRC the manual states that wow locks the handle, once airborne and gear up, handle is locked in the up position until the button is pressed.
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@Boxer said in Shared Memort bit "gear solenoid":
@Tulkas – you gotta read the whole flightData.h
Look for MLGWOW and NLGWOW in LightBits3 - those are the weight on wheels predicates. There is only one for both mains, that’s deliberate.
I did, I did. I’m aware of the two WOW bits, but still not sure if they give me all I need. Would they just send info of weight on/off the wheels with gear down, what does that bit do with gear up? Still sending weight off? I need a bit to account for three situations:
-Gear up, solenoid is unpowered, lever locked
-Gear down, airborne, solenoid is powered, lever unlocked
-Gear down, on the ground, solenoid unpowered, lever lockedSo, would the MLGWOW send the correct signal to the solenoid or is it just a weight on/off? I thought the “solenoidStatus” maybe is a more complete bit with all the logics already on it.
The DN LOCK REL is mechanical in my box so it does not need interaction with BMS. The same for the consent button, it will just connect electrically to the solenoid
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@Tulkas said in Shared Memory bit "solenoidStatus":
@Boxer said in Shared Memort bit "gear solenoid":
@Tulkas – you gotta read the whole flightData.h
Look for MLGWOW and NLGWOW in LightBits3 - those are the weight on wheels predicates. There is only one for both mains, that’s deliberate.
I did, I did. I’m aware of the two WOW bits, but still not sure if they give me all I need. Would they just send info of weight on/off the wheels with gear down, what does that bit do with gear up? Still sending weight off? I need a bit to account for three situations:
These bits represent literal reflections of the mechanical switches on the landing gear struts. When the strut extends the switches open, and the bit shows the no-WOW condition (i.e. bit is zero). When the strut compresses, the modeled switch closes and the bit goes to 1, weight is on the wheels.
Since the gear struts are extended in the wheel well when they-re up, there is no WOW and the bits will all be zero as the switches are open.
This is all a natural side effect of the modeling of the ground handling…you’ve noted that the jet will “bob” when you stab the brakes on the ground, right?? The struts are extending and compressing when that happens and all that has to be modeled so that it looks right from the outside views…wheels remain in contact with the ground etc.
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I did some experimentation. I use AIC (Aircore & Interface Controler) that has a output named “Gear Solenoid” which I assume reads the status of the shared memory bit “SolenoidStatus”. I just connected a multimeter to the output to check what was it doing on every situation:
It turns out that the AIC “Gear Solenoid” bit is basically a MAIN GEAR WOW SENSOR.
So the solenoid is powered all the time except when the three wheels are on the ground. That means I have to break the circuit when the gear is up, to unpower the solenoid, and then close the circuit with the permission button so I power the solenoid and I can lower the gear
