Skipping Lightly Through Heli & Flight Modes for Quality Time in Inputs (5/13)

OK, Welcome Back.  We SP PAGE forward into the “Heli” set up screen (pg 3 of 13).

This is the first of those two optional screens that you’ll find only if you accepted ‘Heli’ in the Radio Set Up.  We won’t worry about set up on the Heli screen because Helicopters don’t really fly. They’re so ugly the earth just naturally repels them 🙂 .  Besides, we’re setting up a basic airplane, and there’s a complete Heli set up class starting up next door with ArchmageAU.  We’ll leave pg 3 to them.  Gee that was quick and fun.

———————————————————————————————————————————- Let’s SP PAGE forward into the “Flight Modes” screen (pg 4 of 13).

Flight Modes allow us to combine several actions into one switch.  For example DLG pilots have one configuration of controls for launching, others for cruising, working a thermal, and descending, and yet another for landing.  For our Basic Airplane set up, we won’t need flight modes.   Rather than explaining the fields now, we’ll defer that to a follow up class in which we will learn all kinds of cool things that can be done with Flight Modes.  An interesting piece on Flight Modes is available under Special Interests — Helicopter if you’d like to check it out.  We move on.


SP PAGE takes us into the “Inputs” screen (pg 5 of 13). 

Up to 32 radio control channels can be managed with OpenTX on the Taranis.  The inputs that are managed by those channels are determined in the “Inputs” screen (Who said this stuff was hard to understand?).  Selecting and configuring the inputs for each active channel is the first link in the command chain that sets up your model.

At this point, the channels can be thought of as virtual channels because they don’t actually correspond to receiver channels yet.  You will assign them to a physical receiver channel later in the Mixer.  Multiple lines of instruction are used to switch-select inputs with combinations of weights (rates), curves (e.g., expo), one-sided action, and flight modes to configure a given channel.  As many lines as you need may be assigned to a channel using LP ENT to popup a menu allowing you to edit a line or to add/delete/move lines.

For each channel, the first line with a switch assignment that is TRUE (starting from the top) will be the active set up condition.  Over 100 sources of input may be combined into a given channel with switch-selectable weights, curves, and up to 9 flight modes.  Switches may be physical switches, logic switches, or trimmers.  The combinations of inputs, weights, curves, and switches provide unlimited flexibility for configuring a given channel.  Because of this extreme flexibility, a generally accepted best practice concludes the input definitions for each channel with a last line having 100% weight and no physical or logical switch.  This is done to avoid an undefined control if the user inadvertently creates a set of inputs that does not achieve a TRUE condition.  This concluding statement for each channel insures that the channel is always available and is sometimes called a failsafe default.

Our Basic Airplane set up will keep it simple.  We’ll configure the 4 basic stick inputs each with three rate/expo combinations activated by SB, a 3-position switch.  The “Expo” curve is familiar so we’ll stay with that, although many other curves are available.  We won’t need Flight Modes or single-sided gimble action in our basic set up.  We won’t know whether the selected weights (rates) produce the desired control surface throws until the final step in the command chain is completed and we measure the deflections.  Nor will we know if the assigned Expo values have the right “feel” until we fly the model.  But this will give us a starting point.

A Special Note:  We set up triple rates on a 3-way switch because it keeps the class simple and avoids complexities.   If you prefer only dual rates, please go ahead and include a “middle” rate between your Hi/Lo preferences for now.  Otherwise you could inadvertently invoke that failsafe default discussed above to prevent a ‘no rates’ condition.   We include the default safety entries below anyway.   Thanks……….. R

Button navigation is a little different in some of the Inputs fields.  For naming, use +/- as normal to browse to the desired field; SP ENT to select the field; then LP ENT to pop up 6 choices –> Edit, Insert Before/After, Copy, Move, Delete.  The first pass we want Edit, and then later we’ll use Insert After for new lines in subsequent passes; SP ENT to edit; +/- to browse letters, then SP ENT to select the letter (LP ENT toggles the capital letter with the lower case); +/- to edit the next letter.  Exit to finish naming.

OpenTX works hard to make our configurations as easy as possible in any screen.  Anytime you need to select a mechanical input in a configuration step, wiggle that stick or switch while the selection field is active and OpenTX will recognize the selection.  The four basic sticks are offered to us in the Inputs screen to get started initially.

The first pass through a line of the Inputs screen we set up Ail 3D, another pass for Ail Hi, and a 3rd pass for Ail Lo, each getting its own line.  Please individually create the lines for IAil according to the table of settings below, then check your results against the first screen shot of the Taranis following the detailed instructions.  After that, we’ll try out the copy feature to reduce the workload for entering Elevator, Rudder, and Throttle settings.  There are lots of button pushes here, so take your time and soak in the learning opportunity:

Source Wt % Expo % Switch Name
Ail 100 60 SB↑ Ail 3D
Ail 65 45 SB — Ail Hi
Ail 40 30 SB↓ Ail Lo
Ail 100 Ail Safe


A important note:  The details in Weight emphasize not using negative weights in Inputs to reverse servos.  Servo reversals should be accomplished in the Servos screen to avoid creating conflicting or confusing relationships in Inputs and Mixer.

If you’ve worked through this successfully so far, your Taranis screen should look like the one below.  Don’t forget you can click to blow it up for better viewing and use browser Back to return.  If you had trouble with an entry, try going back to the detailed instruction for that field:

Click to enlarge; BACK to return

Example Aileron Inputs

Example Aileron Inputs

Now that you’re familiar with the process, let’s finish configuring the remaining control surfaces with the settings in the next table.  For throttle, we leave the default source as the Throttle stick with its own trimmer and 100% weight with no curves or switches.  Remember that our order of entering the inputs here does not determine the receiver channel that will handle a given input.  

Source Wt % Expo % Switch Name
Elevator 100 60 SB↑ Ele 3D
Elevator 60 45 SB — Ele Hi
Elevator 30 30 SB↓ Ele Lo
Elevator 100 Ele Safe
Rudder 100 60 SB↑ Rud 3D
Rudder 60 45 SB — Rud Hi
Rudder 30 30 SB↓ Rud Lo
Rudder 100 Rud Safe


When you’ve finished, the screens for Inputs Pg 5 on the Taranis should look similar to this:

Example Inputs Top Screen

Example Inputs Top Screen

Example Inputs Screen Continuation

Example Inputs Screen Continuation

We set up SB as a combination switch to change rates on all three control surfaces with one switch.  Many pilots prefer to separate their control surface rates onto different switches.  You now see how easy that would be in OpenTX to simply call for a different switch on each input, and the Taranis gives you lots of switches to chose from.

Recall that the Channel Monitor back in Main Screens provides a graphical display of what you’ve chosen above in Inputs.  LP MENU is a short cut to the Channel Monitor from any of the Model Set Up screens, and EXIT returns to the screen you started from.  The Channel Monitor values will appear in either % or in PWM microseconds depending upon whether ‘ppmus’ was selected in the firmware download.  Check it out if you want to see the effect of your Input selections.

Nice Work!  Another big bite, but it’s not so scary now, and the worst is over.  Click to move on to Mixer.


Skipping Lightly Through Heli & Flight Modes for Quality Time in Inputs (5/13) — 7 Comments

  1. Thanks Havoc77 and 1Shems — Good comments, and I’ve edited the material above to reflect your input. Best Regards………. Bob R.

    • Wow! I’m gratified that anyone is reading that closely. There should be an award for greatest attention to detail. I’ve corrected the inconsistency. Thanks for the feedback. I hope that the article has been useful for you. Best regards……….. Bob R.

  2. Very good write on inputs but the developers say you should leave the default line of 100% and no switch to stop a case of no input to the mixer if one of the switched lines doesn’t match. This is very important IMO.

    • Hello Bobferg — Thanks for the reply — the observation you make is correct. There’s always a “however” isn’t there? In this case the scope of the class included showing how to set up reduced rates, so triple rates were chosen for a 3-way switch. A “Special Note of Caution” was added and emphasized in the text to warn against trying to set up dual rates on a 3-position switch for the very reason that you cite. I felt that not providing reduced rates would be a significant reduction in educational value that most flyers would prefer to have, but I also thought that folks just starting out probably were not ready for the complexities of programming dual rates on a 3-position switch. I decided to ask the student to go ahead and add a third rate between the Hi and Lo rates frequently used, and I provided an explanation of why with the cautionary note of what could happen if they don’t. Two different approaches to the same concern. Thanks for the input.

      • I think what was meant is to Always have one line, in addition to the lines you programmed, without a switch or even any other “condition”.

        This makes sure that even when you delete or do other fun stuff to the condition used, you can never create an undefined state.

        This becomes especially important when using other conditions than switches, but nonetheless, this would be the place to introduce this ” good programming practice “.

        Sort of ” fail safe”


        • I agree that this would be a better practice. Because only the first true line, is the active one, the defaults have to go last I believe. It would be good to alter the instructions to say not to edit the default lines, but to use the “insert before” option to add everything else.

          Therefore you would end up with something like:

          Source Wt % Expo % Switch Name
          Ail 100 60 SB↑ Ail 3D
          Ail 65 45 SB – Ail Hi
          Ail 40 30 SB↓ Ail Lo
          Ail 100 Ail

          (Hope that formats ok)

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