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ixeg 737 datarefs issue - values don't match what is displayed on MCP


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All,

I have installed the ixeg 737 and trying to interface my MCP with it. What I noticed is that ixeg published dataref values (looking through dataref inspector) are different from what actually is displayed on the MCP, Ex:

ixeg/733/MCP/mcp_cplt_course_act

ixeg/733/MCP/mcp_plt_course_act

This is also true for other ixeg datarefs such as heading, V/S. What's going on here?

As a side point, the values in Xplane's standard datarefs match what's displayed on the MCP:

sim/cockpit2/radios/actuators/nav1_obs_deg_mag_pilot

sim/cockpit2/radios/actuators/nav2_obs_deg_mag_pilot

 

Please advise.

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Oh, ... I think I understand the issue here ... anything with suffix _act mean actuator position ... not the actual MCP A/P value ...

Okay, so I'll use the Xplane's dataref for Course/hdg/alt/speed. But what about V/S? How do I set this value? Xplane's dataref sim/cockpit2/autopilot/vvi_dial_fpm is ignored and you don't seem to have a dataref for it. 

Please advise.

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There is sim/cockpit/autopilot/vertical_velocity which is a writable float dataref for "Vertical speed to hold".

I assume this is the default X-Plane dataref for vertical speed, but it's ignored by the IXEG. I therefore also assume that the IXEG is using it's own internal "dataref" which is not exposed to the outside world.

I think this is one for Tom to have a look at.

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I was using "sim/cockpit2/autopilot/vvi_dial_fpm" which works fine with standard Xplane aircraft, unfortunately like you said, IXEG uses an internal dataref.

FYI: The interface documentation is out of date. The command "ixeg/733/autopilot/TOGA" has been removed from latest version but is still in the documentation.

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Quick question to Litjan:

Is there a dataref exposed that allows me to check whether throttle servos are engage or disengaged at any point in time? 

I have throttle quadrant that is motorized but as you know with A/T armed, the servos can be disengaged and the re-engaged under various circumstances such as on T/O or during descend using LVL change mode.

Right now, I only look at the MCP's n1/speed/lvl change modes to determine when to engage the A/T servos but unfortunately that's not sufficient.

Any help would be appreciated.

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VVI wheel dataref actuator is:  ixeg/733/MCP/mcp_vs_target_act

Regarding autothrottle servo, we don't currently have a dataref for that, but we should be able to add one.  I'll have to get with Jan to go over the current functionality and see how we can weave it in.

-TomK

 

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Tom, 

The dataref ixeg/733/MCP/mcp_vs_target_act is only an actuator for moving V/S knob, ... I would like to display the current set V/S in fpm on my 7Seg display on the mcp.

Another question: 

When A/T is active and servos are engaged, currently I am using dataref "sim/flightmodel/engine/ENGN_thro_use" to read the current position of the levers to drive my throttle levers. It works for most part but sometimes my levers retard without reason and then come back again to correct position (I have to investigate further why but it is probably related to the dataref I have mentioned that I use to track my thrust inputs).

The question is: Is this the dataref that I should be using for this purpose? 

Btw, for Xplane's default 737 I use dataref "sim/flightmodel/engine/ENGN_thro" without any issues. This dataref doesn't work with ixeg 737 when in A/T is on and servos are engaged since these values are not populated. 

Edited by html_splash
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rgr, I was responding to your question about how to actuate VVI above.

For the levers, we have the following datarefs to reflect throttle lever angle when in autothrottle:

ixeg/733/engine/eng1_thro_angle    /    ixeg/733/engine/eng2_thro_angle

...FWIW, we also have for the reversers:

ixeg/733/engine/eng1_rev_angle     /   ixeg/733/engine/eng2_rev_angle

Regarding the default 737...as one who used to work for Laminar developing aircraft, they keep their customization to a minimum and develop their models to use the default datarefs.  If some significant functionality were to be missing...we'd just go tell Austin and he'd customize stuff and give us new datarefs....but now that I'm "on the outside", we don't quite have that luxury and so have to go custom and abandon default datarefs when they don't suite our purpose.

....and finally, the dataref for the VS annunciator is:

ixeg/733/MCP/mcp_vs_dial_ann

Hope this helps.

-TomK

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Thanks Tom for detailed explanation.

1) The dataref "ixeg/733/MCP/mcp_vs_dial_ann" seems not to get updated, it is always zero (looking through dataref inspector).

2) The datarefs "ixeg/733/engine/eng1_rev_angle", "ixeg/733/engine/eng2_rev_angle" are read-only so I will have to use the original Xplane's datarefs for setting reverse thrust.

Let me know about #1 item work around.

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We will likely have to revisit the coding of the v/s scroll wheel manipulator again, anyway. Currently it only has a limited numbers of revolutions, so it is possible to "run out" during your flight. The real scrollwheel has no limit, of course.

Cheers, JJan

 

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18 hours ago, Splash said:

1) The dataref "ixeg/733/MCP/mcp_vs_dial_ann" seems not to get updated, it is always zero (looking through dataref inspector).

 

perhaps VS mode wasn't activated?  Were you trying it while sitting on the ground?  Works on this end.

image.png

Edited by tkyler
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Tom, I know what happened.

When I typed this dataref in dataref inspector, it couldn't find it and displayed it as "ixeg/733/MCP/mcp_vs_dial_ann(0)" <= I thought, that it found it and it had a zero value.

Long story short, this dataref never displayed for me in the dataref inspector. I am using Dataref tool by Lee C Baker. What dataref inspector are you using?

I took a leap of faith and programmed that dataref into my GF interface tool anyways and it works. Any reasons why this dataref is not showing up in my dataref inspector?

 

Edited by Splash
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2 hours ago, Splash said:

...... Any reasons why this dataref is not showing up in my dataref inspector?

I really couldn't say.  Are you using "Dataref Tool" as your inspector?    I will say I recall some "absentee datarefs" when I tried it, that I couldn't explain (and could plainly see with DRE)...which is why I went back to DRE for dataref work. I use DRE for dataref feedback and DRT for working with commands.  DRE supports the pipe symbol for "OR", which makes it useful enough for me to isolate whatever datarefs I need.

-TomK

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  • 4 weeks later...

Hello, 

I confirme ixeg/733/MCP/mcp_vs_dial_ann(0) is not displayed in datarefool  BUT its work fine in airmanager ! 

ie : 

xpl_dataref_subscribe("ixeg/733/MCP/mcp_vs_dial_ann", "FLOAT", ap_vspeed_callback)

 

regards, 

 

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