JETI model Duplex REX Assist Series, Duplex REX6A, Duplex REX10A, Duplex REX12A, Duplex REX7A User Manual

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COMPLEX RADIO CONTROL SYSTEM

User Manual User Manual User Manual

Receivers REX

FW 1.05FW 1.05FW 1.05

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1. Introduction ......................................................................................... 04

2. Technical data ...................................................................................... 05

2.1 Properties ..................................................................................... 06

2.2 Important Notices ....................................................................... 06

3. Installation ........................................................................................... 08

3.1 Installation in the model ............................................................ 08

3.2 Power supply ............................................................................... 10

3.3 Operation ..................................................................................... 11

3.4 Binding .......................................................................................... 11

3.5 Range test .................................................................................... 12

4. Quick Setup ........................................................................................... 14

4.1 Airplane ........................................................................................ 14

4.1.2 Choice of flight modes ...................................................... 19

4.2 Multicopter ........................................................................... 21

4.2.1 Optimize multicopter settings ........................................ 27

4.2.2 Choice of flight modes ...................................................... 30

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4.3 Description of flight modes ...................................................... 31

4.3.1 Manual (Assist Off ): Airplanes ........................................ 31

4.3.2 Training: Airplanes ............................................................ 31

4.3.3 Normal (Damping): Airplanes ........................................ 32

4.3.4 Heading Hold: Airplanes .................................................. 32

4.3.5 S ta bi li za ti on o f the h or iz on : A irp la nes a nd

Multicopters ......................................................................... 32

4.3.6 Stabilize: Multicopters ...................................................... 33

4.3.7 Sport: Multicopters .......................................................... 33

4.3.8 Acro: Multicopters ............................................................. 33

4.3.9 Altitude stabilization: Multicopters ............................... 34

5. Additional stabilization features .................................................. 35

5.1 Throttle to PID attenuation (TPA) ............................................ 35

5.2. Airspeed compensation ............................................................ 36

5.3 Additional channels ................................................................... 36

5.4 Camera gimbal ............................................................................ 38

5.5 Connecting an external LED strip ............................................ 39

5.6 Sensor data filtering ................................................................... 41

5.7 Sensor calibration ....................................................................... 42

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5.8 Vibration analysis ....................................................................... 43

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6. Advanced properties ............................................................................ 45

6.1 PID control setting ...................................................................... 46

6.2 “Stabilize” mode sett ................................................................... 47

6.3 Acro mode settings ..................................................................... 48

6.4 Filtering ......................................................................................... 49

6.5 Fail-Safe ........................................................................................ 50

7. Alternative pins configuration .......................................................... 51

7.1 Receiver Outputs ......................................................................... 54

8. Real time telemetry ................................................................................ 55

9. Solving the most common problems ............................................... 56

9.1 General ......................................................................................... 56

9.2 Airplane models ....................................................................... 56

9.3 Multicopter models .................................................................... 58

10. Receiver update and configuring ................................................... 59

10.1 Update the receiver ..................................................................... 59

10.2 Configuring the receiver with a PC ........................................... 60

....

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REX Receivers with Assist Functions

1 Introduction

The REX A receivers enhance the REX series of receivers and extend

it with the intelligent flight stabilization feature, which is designed

for airplane models and multicopters. This stabilization works in all

three axes of the model and facilitates flying in windy or otherwise

challenging conditions. Aerobatic maneuvers will be more

accurate and smoother. With the help of several flight modes,

which are also suitable for beginner pilots, flying practice will be

really easy.

The REX A receivers are compatible with all existing 2.4GHz Duplex

Tx modules and DC/DS transmitters.

You can set them directly via DC/DS transmitters, alternatively you

can use the USBa adapter and JETI Studio software (free download

at www.jetimodel.com). The receivers provide internal telemetry

(e.g., receiver quality, inertial unit status and G-force level). They

also process telemetry from external sensors compatible with

Duplex EX or EX Bus.

In order to stabilize the airplane model effectively in flight, it is

appropriate to equip the model with high speed digital servos.

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Stabilization is also suitable for combustion engine models.

ENGLISH

FW. ver. 1.05

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Basic Data

REX6A

REX7A

REX10A

REX12A*

Dimensions [mm]

38x25x11

42x28x11

51x28x11

Weight [g]

111316

Antenna length [mm]

2x100

2x200

2x400

# of channel outputs

6710

Temperature range [°C]

-10 to +85

Supply voltage [V]

3.5 – 8.4

Average current [mA]

808080

Real time transmission

of telemetry data

Yes

Programming

Tx - DC/DS

Support satellite receiver Rsat

Yes

Power output [dBm]

151515

Receiver sensitivity [dBm]

-106

Frequency [MHz]

2400 - 2483

Built-in sensors

3-axis gyroscope, 3-axis accelerometer

Sensitivity of altitude measurement

0,1m

Range of gyroscope measurement

± 2000°/s

Range of accelerometer measurement

± 16G

Gyroscope/accelerometer sampling rate

6600Hz

The JETI model company portfolio contains a diverse offering of

electronic modelling equipment like voltage regulators, motor

speed controllers, telemetry data display equipment, telemetry

sensors and, last but not least, DC/DS transmitters. The JETI

model product manfacturing policy is to constantly produce the

highest quality product possible.

2 Technical data

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EPC

* xternal ower onnector

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2.1 Properties

 Up to 16 stabilized airplane channels.

 Support for different multicopter types – from tricopters to

octocopters.

 Up to 3 adjustable flight modes, options for stabilizing the

horizon and altitude.

 In-flight gain tuning using free channels.

 Using the latest 3-axis gyroscope and 3-axis accelerometer.

 Support for LED strip consisting of WS2812 chips.

 Support for external camera gimbal driven by servos.

 Intelligent fail-safe.

 Vibration analysis.

 Full set-up options with DC/DS transmitters or via PC.

 Available telemetry: Receiver voltage, signal quality, G-force,

attitude orientation.

 Support of telemetry and up to 3 sensors connected directly.

2.2 Important Notices

 Always use the current firmware in your DC/DS transmitter and

receiver. The minimum version of software for transmitters

supporting REX A receivers is 4.24.

 Always check the polarity of the lead wires so that the voltages

on the receiver and other electronics are not reversed.

 Do not expose the receiver to heat and sudden temperature

changes that may affect the accuracy of the sensors.

 Never use a receiver that is visibly damaged. In particular, check

the state of the antennas regularly. In no way modify or remove

the receiver electronics from the supplied housing.

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 When installing on a combustion engine model, keep in mind

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that all electronics must be optically isolated from the ignition

unit and ideally located as far as physically possible from the

engine itself.

 Do not expose the receiver to excessive vibration. Sensors in the

receiver are very sensitive and vibrations are an undesirable

phenomenon. It is advisable to check the vibration level with the

built-in analyzer before flight and to take appropriate measures

to reduce vibration (e.g. attach the receiver in the model with a

soft double-sided adhesive tape).

 Do not expose the receiver to direct air flow. Aerodynamic forces

may have a strong influence on the sensitive barometric sensor

when the model is moving faster.

 Always use a sufficiently sized power source for the receiver and

servos. Keep in mind that with the stabilization switched on, the

servos in the airplane model are constantly moving, resulting in

increased current consumption and subsequent heating of the

components.

 Any major changes to the settings (especially for the initial

configuration) should be done without the propellers fitted.

 During use, it is recommended to switch on the transmitter first

and then the receiver. The transmitter confirms that the receiver

is turned on by an acoustic signal. When turning off the system,

first switch off the receiver and then the transmitter.

 REX A receivers do not support Clone mode. This is because the

stabilizing receiver should always be the primary receiver in the

model. Other receivers, serving as satellites, must not have the

stabilization enabled.

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3 Installation

3.1 Installation in the model

Always place the receiver in the model parallel to the flight axes and

ideally as close as possible to the center of gravity (especially for

multicopters). This is important for the proper functioning of

stabilization and its correct response. It is important that the

mounting of the receiver is made in such a way that the vibrations

from the model are minimized and that the fixation is guaranteed at

the right place. We recommend using a double-sided adhesive tape

for this purpose.

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Default - Horizontal

Rotated by 90°

Vertical – on the left

Vertical – on the right

Inverted - Horizontal

Standing – on the left

Standing – on the right

Rotated by 180°

There are several ways to place the receiver in the model, and you

need to activate this position in the setup wizard. The direction of

the arrow on the receiver sticker determines its placement:

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3.2 Power supply

When designing a wiring system in the model, always be careful

about choosing a suitable power supply so that it is sufficiently

current-rated and its output voltage is compatible with the

receiver, servos and other electronics. It is recommended that the

REX A receivers be powered by low-resistance Li-XXX type batteries

or a stabilized BEC voltage source (either as a separate device or

integrated in the speed controller).

Never connect two different voltage sources in parallel, even if

the y seem to have the sa me parame ters. Ins tead, use an

additional circuit, such as DSM10, to separate both sources which

become independent.

The supply voltage can be applied to the receiver in the following

ways:

 Via throttle channel (when using the speed controller BEC).

 Using any free or open receiver port.

 Via the MPX connector included on EPC receivers (Extended Power

Connector).

For multirotors, use either a BEC output from a single controller

or, in case of Opto-type controllers, use an external stabilized

source. Never connect voltages from several BEC circuits in

parallel.

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3.3 Operation

We recommend that you switch on the transmitter first and then

subsequently the receiver. The transmitter confirms the switching-

on of the receiver with an acoustic signal. When switching off the

system we recommend that you switch off the receiver first and

then subsequently proceed with switching-off the transmitter.

3.4 Binding

When using a new receiver or transmitter it is necessary to carry out

the binding process between them. Transmission between the

receiver and transmitter occurs in fully digital manner, therefore it is

necessary to identify and share the addresses of each device

communicating on the mutual 2.4GHz frequency band.

Procedure:

1. Insert the BIND PLUG (included in the receiver packing) into the

receiver socket labeled Ext.

2. Switch on the receiver – (connect a proper voltage supply to the

receiver). Binding of the receiver may now be performed within 60

seconds. After the 60 seconds elapse the receiver returns to setup

mode and the binding process must be repeated by starting again

from step 1.

3. Switch on the transmitter - the transmitter emits an acoustic

signal announcing the detection of a new receiver.

Binding may be carried out with the aid of the JETIBOX instead of

using the BIND PLUG.

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The procedure is as follows:

1. Connect the JETIBOX with the connecting cable to the Ext.

receiver output .

2. Switch on the receiver - (connect a proper voltage supply to the

receiver).

3. The receiver menu appears on the JETIBOX display. Select the

„Pairing“ menu item (push the right arrow button once from the

main receiver display) and then push the upward button. You now

have a period of 60 seconds to bind the receiver. After the 60

seconds elapse the receiver returns to setup mode and the binding

process must be repeated by starting again from step 3.

If the binding process between receiver and transmitter was

unsuccessful, try again.

You may bind an arbitrary number of receivers to one transmitter.

The receiver, however, can only be bound to one transmitter, i. e. the

receiver is only bound to the most recently bound transmitter.

3.5 Range test

By range testing, you verify the correct operation of the transmitter

and receiver. You should perform a range test before your first flight

of each flight day, or if there are any doubts about the function of

the transmitter or receiver. In the range test mode, the transmit

power is reduced to 10%. When testing range, place both the model

and transmitter at a height of at least 80cm (3ft) from the ground. A

properly operating transmitter and receiver should reliably control

the model at a distance of at least 50 meters (or 50 yards) in the test

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mode. If this is not the case, be sure to check the correct installation

of the receiver antennas. If the test is not successful afterwards then

do not use the device and contact your dealer or one of our service

centers.

Setting into Range Test mode:

Insert the pairing jumper (BIND PLUG) into the Ext. port of the

receiver, turn on the receiver and then the transmitter. Range test

mode will be active for as long as the bind plug is inserted in the Ext.

port.

 Alternatively, you can run the range test in the DC/DS transmitter

via the System – Servo & Range Test menu.

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4 Quick Setup

4.1 Airplane

From production the REX Assist receivers behave as standard

receivers and stabilization is not active by default. This can be used

to set up an airplane model - the initial procedure is similar:

1. Place the receiver in the model according to the “Installation

in the model” chapter.

2. Create a new model in the transmitter as usual. The individual

channels of the transmitter should correspond with the

outputs on the receiver. If you plan to use additional channels

to tune the stabilization gain or to switch flight modes, this is

the moment you should create them. By doing that you won’t

have to go back to your channel settings while configuring the

receiver via Quick Wizard menu. More information about the

auxiliary channels can be found in the Additional channels

section.

3. Pair the transmitter with the receiver.

4. For the model, set its subtrims, dual rates and expos according

to the recommended values. Do not set up advanced mixes or

change the servo path using servo balancer.

5. Now go to the receiver configuration – either through the

DC/DS menu (Model -> Device Explorer) or via your PC (see

chapter Configuring the Receiver with PC).

6.b) Run the stabilization setup wizard (Configuration -> Quick

Wizard ) . On the first screen, enter the “Airplane Assist”

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option and go to the next page with the “Next” link.

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7. Specify the model type so that its flight characteristics best

match one of the options . Several types of gliders,

aerobatic models and others are available. Each model type

includes preconfigured and optimized stabilization presets so

that the first flights are enjoyable and the additional settings

are kept to a minimum.

8. In the next step, select the receiver

position in the model so that the

displayed graphics matches real

situation. A total of 8 options are

available (see chapter Installation

the model) . Illustration indicates

flight direction.

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d), e)

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9. Now check for additional features

g):

 Use airspeed correction – if the

model is able to move at a large

range of speeds, it is advisable to

supplement it with the MSPEED

sensor or MGPS for measuring

flight speeds. By activating this

field, the receiver will take into

account the current speed while

performing stabilization.

 Us e c ame ra gimb al - by

checking, you enable the function

of an external servo control for

camera gimbal.

 All servos digital - This option

specifies the servo output period. If all the servos are digital in

the model, the output period will be automatically set to

7.5ms. Otherwise, it will be 17.5ms.

10. Assign the individual channels for stabilization so that the

receiver learns neutral positions

and throws of individual servos .

The model can now be placed

arbitrarily because at this point

you only calibrate the control

functions. Proceed step by step

ac cording to th e wizard a nd

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calibrate only the axes that will be

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used during stabilization. Check the correct response to the

controls by looking at values displayed in the “Controls” row. If

the servos in the model are not moving, it is ok at this point -

the receiver will not allow servo outputs until the configurati-

on is completed.

11.f) Assign a channel for switching flight stabilization modes .

This channel should be controlled

by a three- position switch, so that

all three flight modes are available.

In position the stabilization is

disabled by default. Switching to

position (center) activates the

“No rmal” mode. Switching to

position activates the "Heading

Hold" mode.

Note: First add a three-position switch to your DC/DS transmitter

as a new function in the Model – Functions Assignment menu.

Then assign this option to a free channel in the Model – Servo

Assignment menu. Subsequently, this three-position switch can

be used here in the receiver setup wizard.

12. If you have selected the “Use gimbal” option in the previous

steps, assign the individual channels to the gimbal control. You

can skip this point and configure the camera gimbal later in the

Configuration -> Channel Assignment -> Gimbal channels.

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13.j) Finish the wizard and application settings . When you run the

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“A p pl y wi z ar d and f in i sh ”

c o mm an d , y o u s t or e th e

parameters in the receiver and the

stabilization is reset to the mode

according to data you’ve entered.

Attention: At this po int , th e

se tt ings of in div id ual se rv o

outputs, flight mode configurati-

on, and the PID control gains will

be reset.

14. Before each flight, place the model

on the ground and hold it stable

during the gyroscope initializati-

on . On ce t he i nitiali zation is

completed, it is possible to move

servos.

15. Check for correct input control response and stabilization

function when moving in each axis. For example, if you rotate

the model to the left, the control surfaces should tend to move

in the opposite direction.

16. Perform the first flight either with stabilization disabled

(manual mode) or in “Normal” mode. If the model does not fly

straight, trim it and then land. Re-assign the primary channels.

Continue to optimize the settings so that the flight characteris-

tics of the model match your preferences.

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4.1.1 Airplane model settings

optimization

In the “Airplane Settings” menu in the

REX A configuration you can fine- tune

the stabilization gains for individual

axes.

Gain - This parameter determines the

proportional rate of model stabilizati-

on in flight. If the model is insufficiently

stabilized, for example in wind gusts, increase the gain each time by

20% until the model starts to oscillate. Consequently, reduce your

value by 20%. Try the new settings at different flight speeds and

make sure that even at high speeds there are no oscillations.

Heading - Determines how intensively the model keeps its

orientation and direction in the “ Heading Hold ” mode. In

“Normal” mode, this parameter is not used. You can test the

function of heading hold function, for example, when you are in

knife edge flight.

3D Aerobatic Factor (Stick Priority) - Determines how the

stabilization gain decreases depending on how the control stick

moves from the center position. For instance, a 60% aileron stick

priority means that at maximum left or right, the aileron gain will be

reduced to 40% and the stick direct position will be applied from

60%.

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4.1.2 Choice of flight modes

De pen din g on your pr eferenc es,

choose which flight modes to use

during flight - a total of 5 modes are

availab le, allowing you to switch

between three in flight (see Descrip-

tion of flight modes section).

Spe ci fy th e Fail -S af e m od e: In

Intelligent mode, the receiver will

stabilize t he model in horizontal

position. On the other hand, selecting

“Assist Off” will apply preset servos

positions, or the last known position

will be retained (see the Configuration

– Fail-Safe menu for more details).

For each Flight mode, you can set the

default gain (this multiplies the stabilization gain and the heading-

hold ability in all axes). You can also specify whether to use the gain

tuning via special dedicated channels (see Configurati on -

Channel Assignment - Assign Additional Channels).

For each flight mode, it is also possible to specify which servos are

stabilized by which function. By default every combination of

functions is allowed. If you do not need to have e.g. a stabilized

rudder in all flight modes, simply deactivate it in the appropriate

line.

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4.2 Multicopter

Before you connect and configure the REX A receiver for the first

time in a multicopter model, we recommend disconnecting speed

controllers with motors from the receiver to avoid accidental

spinning.

1. Remove the propellers from motors.

2. Place the receiver in the model according to the Installation in

the model chapter.

3. In the transmitter, create a new multicopter model. When

setting up, make sure that Motor/Throttle, A ileron/Ro ll,

Elevator /Pitch, Rudder/Yaw and Flight- Mode switching

functions are operated separately on each channel.

4. Pair the transmitter with the receiver.

5. a) Navigate to the receiver settings either via the DC/DS menu

(Model -> Device Explorer) or via USB adapter and JETI Studio.

6. b) Run the stabilization setup wizard (Configuration -> Quick

Wizard). On the first screen, enter the “Multicopter Assist”

option.

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Tricopter Y

Quadcopter +

Quadcopter X

Hexacopter +

Hexacopter X

Hexacopter Y

Octocopter + (REX10 A or

REX12A)

Octocopter X

(REX10 A or REX12 A)

7.c) d) Select the type of your multicopter frame and continue to

the next page by pressing the “Next” link. The following types

of frames are supported (direction of rotation and motor

sequence must always be observed):

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8.e) On the next screen , select the

multicopter characteristics to best

match your model. Each type

inc ludes preco nfig ur ed and

optimized presets for stabilization

so that th e f ir st fl ights ar e

enj oy ab le an d a dd ition al

settings are kept to a minimum.

9.f) In the next step , select the

receiver position in the model so

tha t the d is play ed gr aphic s

matches real situation. A total of 8

options are available (see chapter

Installation in the model). The

illust ration ind icates fli ght

direction.

10.g) Now check for additional features :

Use camera gimbal - by checking this option, you enable



the function of the external servo-controlled camera gimbal.

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

All servos digital - This option specifies the output period

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fo r s er vos th at are use d a s

additional channels. If all the

servos in the model are digital, the

output period will be automati-

cally set to 7.5ms. Otherwise, it

will be 17.5ms. The output

control period for the motors is

2.5 ms, which means 400Hz.

Use OneShot125 - by checking this option, you enable the



OneShot125 mode to control the multicopter speed

controllers. This is a special mode where the pulses from the

receiver are eight times shorter than the standard servo

pulses. OneShot125 must also be supported on the controllers

side.



Always stabilize motors - after activating this option, the

multicopter will be stabilized from the moment of arming and

the first throttle application until switching off the motors.

Stabilization will always work, even with throttle at idle

position. This option is not recommended for first flights with a

multicopter.

11. Assign the individual channels for

stabilization so that the receiver

le arns neutr al po sit ions and

channel throws . Follow the step

by step guide. Calibrate all

axes sequentially one by one.

Check correct responses to the

controls by the values displayed in the “Controls” row.

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12. Assign a channel for switching flight stabilization modes. This

channel should be operated by a three- position switch, so

that all three flight modes should be available. In position 1

the altitude and horizon stabilization is enabled by default.

Switching to position 2 (center), a

simple horizon stabilization mode

with direct throttle is activated.

Switching to position 3 activates

the aerobatics mode.

Assign the throttle channel. Make

sure this channel on t he

indicator works in the range 0-

100% (1-2ms).

13. If you have selected “Use gimbal”

in the previous steps, assign the

individual channels to control it

j). You can skip this point and

configure the camera gimbal

later in the menu Configuration -

> Channel Assignment –> Assign

gimbal channels.

14. Finish the wizard and application

settings . After executing the

“Ap ply w iza rd an d fin ish”

command, the parameters in the receiver are stored and the

stabilization is reset to the mode according to the data you’ve

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entered.

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Attention:

At this point, the settings for individual motors/servo outputs,

flight mode configurations and PID control gains will be reset.

15. In the Configuration -> Multicopter Settings menu, test the

correct rotation direction of the motors according to the

diagram displayed on the top of the screen.

16. Now lay the model on a flat surface - once the stabilization is

initialized, the speed controllers usually respond by beeping.

Try arming the motors (still without the propellers attached):

With the throttle at idle position, move the two sticks to the

extreme positions (the elevator fully up and the ailerons with

the rudder towards each another):

Motors should start spinning and after 3 seconds without

applying throttle they should stop. If the motors are not

spinning, check the “Minimum running throttle” parameter

in the Configuration -> Multicopter Settings menu.

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17. Before your first flight, it is necessary to test the stabilization

reaction with the propellers, ideally when the model is

mounted on a test bench which allows rotation in only one

axis. It is necessary to ensure that the model in the Aerobatic or

Sport mode is able to maintain a constant direction at zero

stick movement and also to avoid undesirable oscillations.

18. Make your first flight in calm air on a grassy or other soft surface

with plenty of space. Start by arming the motors and lightly

adding throttle. Use small stick movements to make sure that

the receiver responds in correct direction of each axis and tries

to stabilize the model. If you experience any unexpected

behavior, be prepared to immediately lower the throttle and

land. Continue flying in one place and at low altitude - if the

flight is unstable or oscillation occurs in any axis, land and

adjust the gain of the PID control loop (see the next chapter).

Retest the new setting again in flight.

4.2.1 Optimize multicopter settings

Before your first flight with a multicopter model, always test the

rotation direction of the individual motors. In the receiver

configuration, go to the Multicopter Settings menu. Here, choose a

minimum value for running throttle to make the motors slowly spin

when the multicpoter is armed.

Set parameters Throttle Off and Maximum throttle according to

the recommended setting from the manufacturer of your ESC.

Test the rotation direction of each motor by activating the

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command “Test motor N”. The corresponding speed controller

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recei ves a command to run at

minimum revolutions for approximate-

ly 1s. The rotation direction must

correspond to the diagram in the menu

on the transmitter display. If the motor

rotates in the opposite direction, swap

any two motor leads between each

other.

Overwrite all motors - you can enter

any value from 0.8 to 2.2ms, which is

sent to all motors at the same time after

the F4 “A pp ly ” bu tt on on the

transmitter is pressed.

Use OneShot125 - Check this option

to enable OneShot125 mode for controlling the multicopter speed

controllers. This is a special mode where the pulses from the

receiver a re 8 times shorter than standard servo pulses.

OneShot125 must also be supported by the speed controllers in

your model.

Always stabilize motors - after activating this option, the

multicopter will be stabilized from the moment of arming and

applying the throttle for the first time until the model is disarmed,

which means the motors are switched off. Stabilization will always

work even with the throttle at idle position. This option is not

recommended for first flights with your multicopter.

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If the multicopter is capable of flying,

but its behavior is not entirely ideal, it

will be necessary to fine-tune the PID

gains of the stabilization loop - see the

C o n f i g ur a t io n - > A d va n c e d

Properties menu. Here you can edit

individual coefficients for each axis

separately.

Proportional coefficient – this is a basic parameter of stabilization.

The response of the control unit is directly proportional to the

desired rotation speed. If the multicopter is not sufficiently

stabilized in some axis, e.g. the pilot must always interfere with the

steering to keep the model in the air, increase this factor (at each

step, for example, by 20%). Once the oscillation starts, reduce the

proportional factor by 20%.

Integral coefficient - determines the weight of stabilization error

accumulated from the past. Thanks to integrating, the receiver is

able to return the model to its original orientation, even if it has

been previously displaced. Set this factor so that the model does

not tilt in the air in any axis and keeps a steady attitude in the Sport

or Acrobatic mode. If the coefficient is too high, slow but strong

oscillations might appear.

Derivative coefficient - The derivative component of the

stabilization loop responds to rapid changes in model orientation

and is able to suppress, for example, the effects of wind gusts. Edit

the value of the derivative component very carefully with small

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steps, as the model might begin to oscillate very quickly.

When testing the modified coefficients, take off and apply small but

fast movements on the inputs and check if the multicopter reacts

quickly, but without overshots. The rudder axis (Yaw) is not so

critical for fine tuning the gain - after moving a stick in yaw

direction, the multicopter should not become unstable and should

not experience significant changes in altitude. Leave the derivative

coefficient at zero.

For multicopter models, the altitude and climb/descent stabilizati-

on can also be tuned. If the model responds more violently than

expec ted to the climb comman d, lower the proport ional

coefficient in the appropriate row (Vertical Speed). Conversely, if it

does not respond to the altitude change at all, increase the

coefficient value.

4.2.2 Choice of flight modes

De pen din g on you r prefere nces,

choose which flight modes to use

during flight - a total of 5 are available,

switching between three is available

(see the Description of flight modes

section).

For each flight mode, you can set the default gain (this multiplies

the proportional, integral and derivative coefficients in all axes),

and you can specify whether you want to use gain tuning via special

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chan nels (see C onf igu rat ion -> Chan nel Assignme nt ->

Additional Channels Assignment).

Determine the fail-safe mode:

In intelligent mode, the receiver will stabilize the model horizon (at

the last known throttle level). On the other hand, when selecting

“Assist Off”, all engines will be stopped.

4.3 Description of flight modes

In the REX Assist receiver, you can switch between several flight

modes, with the 3 default ones being preset. The default flight

modes can be replaced by any combination of the following

modes:

4.3.1 Manual (Assist Off): Airplanes

The basic airplane mode where the stabilization function is

completely deactivated and the pilot takes over the manual

control.

4.3.2 Training: Airplanes

This mode is used by the pilot to get accustomed to the model's

behavior, and is also useful for beginners. Basically the stabilization

does not interfere with the steering when the model flies

horizontally. However, as soon as you want to make a maneuver, the

stabilization will not allow you to exceed the maximum safe angles

for tilting the aileron axis or the elevator. Aerobatics in this mode is

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not possible.

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4.3.3 Normal (Damping): Airplanes

This is a basic mode for flying in the wind, suitable for takeoffs and

landings. Stabilization works in 3 axes and suppresses the effects of

external forces like wind turbulences or gusts. Aerobatics may be

unlimited. In this mode, you can use trims even for stabilized axes.

4.3.4 Heading Hold: Airplanes

A mode designed for those aerobatic figures where it is necessary

to maintain the constant flight direction. These include, for

example, hovering or knife edge flight. Do not use the Heading

Hold mode at takeoffs or landings, as there may be a risk of stalling

at low speeds and the stabilization would increase the effect even

more, which could lead to a crash. Do not use trims in this mode,

because any shift of the center position will be perceived as an

instruction to start rotation.

For gliders, do not use Heading Hold mode if the model is moving

at or near stall speeds (typically when sailing in thermals). The

model stops being sensitive to climbing currents, and then

dropping and falling may occur because the stabilization

correction is not able to fully return the model to its original

orientation with the only function of control surfaces.

4.3.5 Stabilization of the horizon: Airplanes and

Multicopters

Stabilization of the horizon is also suitable for beginners. In this

case, the stabilization algorithm makes it possible to perform basic

aerobatics, but if the pilot leaves the controls in the center position,

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the model is leveled to horizontal flight. For airplane models, keep

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in mind that it is necessary to maintain sufficient speed, as the

Heading Hold mode is active at the same time.

4.3.6 Stabilize: Multicopters

The basic functions of the RE X A receiver to stabilize the

multicopter. The model is kept in a horizontal position during the

flight, with the position of the controls indicating the pitch and roll

angle of the multicopter. Maximum tilt angles can be defined in the

Configuration - Advanced Properties menu, by default it is set to

±45°. In this mode, altitude stabilization is not active, and there is no

possibility of aerobatics.

4.3.7 Sport: Multicopters

This mode allows basic aerobatics even for multicopters, since the

receiver only stabilizes the rotation speeds in individual axes and

does not level the model to the horizontal flight. Altitude

stabilization is also deactivated. The transmitter sticks control the

rotation speed of each axis, the maximum speed can be defined in

the Co nfigu ratio n - Ad vance d P rope rt ie s menu (M ax .

roll/pitch/yaw rate).

4.3.8 Acro: Multicopters

This mode is similar to the Sport mode, additionally with direct stick

input applied (adjustable in Configuration - Advanced Properties

- Aerobatics Factor/Stick Priority). E.g. The 60% aileron stick

priority means that at maximum left or right stick position, the

aileron stabilization gain will be reduced to 60%, and from 40% the

direct stick position will be applied.

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Default flight mode configuration for airplanes

Position 1

Position 2

Position 3

Manual

(stabilization off)

Normal stabilization

mode

Heading Hold

Default flight mode configuration for multicopters

Altitude and horizon

stabilization

Horizon stabilization

Sport

4.3.9 Altitude stabilization: Multicopters

This mode is similar to the Stabilize mode, with the climb and

descent rate being stabilized. The throttle position indicates

vertical velocity. In the neutral position of the stick (which is around

1.5ms), constant altitude is stabilized. By adding the throttle, the

model starts to climb.

Caution:

If you completely pull the throttle to idle position to reach the

maximum descent speed, keep in mind that if you do not use

Al ways sta bili ze moto rs op tion , the stab iliz atio n wil l be

co mple tel y d eact iva te d and th e mod el ma y c ras h. We

recommend not fully pulling the throttle when descending, or

shifting the throttle curve on your transmitter.

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5 Additional stabilization features

Additional functions of the REX A receivers can be used to fine tune

or extend the basic stabilization functionality.

5.1 Throttle to PID attenuation (TPA)

This feature is available for multicopter models to help suppress

oscillations when throttle is pushed rapidly. If the model flies well

with low throttle, but begins fast oscillations when adding throttle,

set “T PA bre ak po int” and “T PA val ue” in th e m enu

Configuration -> Advanced Properties. Set the breakpoint below

the level at which the oscillations begin and gradually increase the

TPA value in increments of 10%, until the flight is comfortable even

with full throttle.

Example of TPA setting in a graph: “TPA breakpoint” = 50%,

“TPA value (PID reduction)” = 50%. If you set more than 50%

throttle, the stabilization gain will begin to decrease to a final 50%

at full throttle.

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5.2 Airspeed compensation

This feature is available for airplane models and helps to suppress

oscillations in stabilized flight at high speeds. As the control

surfaces efficiency increases at the same time as the speed

increases, the stabilization gain in the individual axes should be

adjusted accordingly with respect to the actual speed so that the

resulting stabilization effect is constant throughout the flight and

there are no inappropriate reactions.

The airspeed compensation function can be comfortably used in

turbine models that are able to move at a high range of speeds. To

determine the speed compensation correctly, the model must be

equipped with the MSpeed EX sensor (measuring airspeed) or

MGPS EX (measuring absolute speed with respect to the Earth's

surface). We recommend using an airspeed sensor, which is

important for the model's behavior and flight characteristics, for

example at stall speeds. The MGPS sensor is simpler to install, but

this sensor does not take into account the wind speed, so that the

function of compensation won’t be accurate in strong wind and at

low speeds.

Airspeed compensation setting: In the Receiver Configuration,

you will see the “Advanced Properties” menu and the “Speed-

PID Attenuation” section. Set the “Optimize for speed”

parameter to a usual flight speed, where no oscillations occur. From

this speed, the stabilization gain will be gradually reduced.

5.3 Additional channels

To assign additional channels, locate Configuration -> Channel

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Assignment -> Assign Additional Channels. For proper operation,

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each channel must first be created on the transmitter – when using

DC/DS transmitter via the Model menu -> Function Assignment

and Servo Assignment.

Flight mode switching channel - here you can assign a

dedicated channel to switch flight modes. This channel should

ideally be operated by a three-way switch on the transmitter.

Throttle channel - is important for multicopter models. A

proportional throttle control channel will be shown here.

Fail-Safe channel - Here you can assign a dedicated channel

operated by a two-position switch that, after switching to the active

position, will simulate the signal loss event. The servos will move to

their predefined positions afterwards.

Assist-Off channel - Here you can assign a dedicated channel

operated by a two-position switch, which, when switched to the

active position, forces the stabilization to switch off (i.e. the airplane

model will enter the manual control mode while the multicopter

stops the motors immediately).

G a i n t u ni n g c h an n e l s :

Ailerons/Roll, Elevator/Pitch

a nd R ud d er / Yaw - a ss ig n

proportional channels controlling

stabilization gains in each axis if

needed. Positive value increase up to

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do ubl e the defau lt g ain , while

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negative percent values decrease to a minimum of 10%. The value

of 0% corresponds to the unchanged default gain value.

5.4 Camera gimbal

REX A receivers support the connection of up to three-axis camera

gimbal, whose individual axis (roll, tilt

and pan) are controlled by ser vos

connected to individual channels. If

you plan to use this feature, activate it

in the Assist Setup Wizard, click “Use

gi mb al”. You can c onfi gure the

individual outputs for the gimbal

servos either by going through the

wizard (step 7) or in the Configuration -> Channel assignment

menu - >Gimbal channels:

Gimbal Roll - Shows the channel assigned in the transmitter to tilt

the camera to the left and right. The same channel will be used on

the receiver side for the output of the given camera gimbal axis.

Maximum roll - Specifies the angle at which the tilt servo is at its

maximum displacement. Set this value so that the image stays

stable when moving the model and does not tilt left or right.

Gimbal Pitch - Shows the channel assigned in the transmitter to

tilt the camera up and down. The same channel will be used on the

receiver side to output the given camera gimbal axis.

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Maximum pitch - Specifies the angle at which the servo is tilted

to its maximum deflection. Set this value so that the image is stable

when moving the model and does not tilt up or down.

Camera Yaw (pan) - Shows the assigned channel on the

transmitter to rotate the camera. The same channel will be used on

the receiver side to output the given camera gimbal axis.

Maximum yaw - Specifies the angle at which the servo is rotated

to its maximum deflection at maximum damping. Set this value so

that the image is stable when the model moves and does not rotate.

Damping (dmp.) - Damping factor in the rotation axis. The

higher the value, the longer the camera will stay in the original

direction, and it will take longer time for it to turn to the new

direction. At 100% the gimbal will always try to keep the original

orientation.

5.5 Connecting an external LED strip

The REX A receivers support the connection of an external LED strip

consisting of up to 32 programmable

RGB LEDs of the WS2812 type. A single

receiver port is dedicated to the strip,

which must first be configured to

enable the strip. In the Configuration

–> Al tern ative P in C onfi gura tion

menu, select the dedicated output pin

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Off

The LED is off

Arming State

The color indicates the “Armed” and “Disarmed”

states.

Flight Mode

The color indicates the active mode from three

possible.

Roll Left

Blinking in orange indicates the tilt in the aileron

axis to the left.

Roll Right

Blinking in orange indicates the tilt in the aileron

axis to the right.

Color

The following are available: white, red, orange,

yellow, lime green, green, mint green, cyan, light

blue, blue, dark violet, magenta, deep pink.

and switch it to “LED Strip” configurati-

on. The “LED Strip Settings” link then

appears in the receiver configuration,

allowing you to change the colors and

functions of the individual LED chips.

The connection of LED strip itself is simple, you can connect the

three-core cable terminated with the JR connector on the input

side of the strip (with the pad marked Din). This connector is then

plugged into a dedicated port in the receiver.

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5.6 Sensor data filtering

REX A receivers embed advanced digital algorithms for filtering

sensor data. The algorithms are designed to suppress undesirable

effects caused by vibrations in the model. Two types of filters are

used:

Low Pass Filter - This type of filter transfers frequencies below

the set limit and all higher frequencies are suppressed. Its basic task

is to separate the desired data containing changes in model

attitude (low frequency) from unwanted vibrations (high

frequencies).

Band Filter (Notch Filter) – It’s used to filter out specific

frequencies caused by engine vibrations. You can additionally

activate this filter if the vibrations caused by the engine are

relatively high. Check the vibration level regularly via “Vibration

Analysis” receiver menu with the engine running. The engine

should run at such revolutions as are most common in flight.

Example of band filter adjustment:

The illustration shows vibrations of a

motor that rotates at 200Hz, 12000

rpm. We will choose the average filter

frequency of 200Hz, as there is a peak in

this area. We set the filter bandwidth

somewhere between 50-150Hz. The

narrower the filter bandwidth, the

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more precisely the filter will be able to reduce the signals with the

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specified frequency. However, as the motor speed and thus the

vibration frequency changes during flight, it is preferable to choose

wider bandwidth, approx about 100Hz.

Set both types of filters in the Configuration -> Advanced

Properties and the Filtering section.

5.7 Sensor calibration

Sensor calibration is important for the

correct and accurate func tion of

stabilization. The receiver calibrates

the offsets of an internal gyroscope

automatically, always after the receiver

is switched on. Approximately for 2

seconds after turning on, keep the

model at stationary position. It’s not

required to keep the model horizontally, but the tilt angle should

not exceed 30°. Once the gyroscope is calibrated, the stabilization is

armed and ready for flight.

The internal barometer is being calibrated at the same time as the

gyroscope to create a reference zero level for calculating the

relative altitude.

Calibration of the accelerometer is a more complex process. The

receiver is already calibrated from the factory, but due to the Earth's

gravitational field, which is not constant all over the planet, the

accelerometer can show inaccurate measurements. We recom-

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mend you to calibrate the accelerometer also when you configure

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the receiver in a new model for the first time:

In the receiver menu, view Telemetry -> Sensor Calibration screen.

Activate the “Start calibration” command and follow the

instructions. The receiver must be placed on a horizontal board

with one of its six sides and kept still for about 2 seconds. Once the

position is correctly recorded, the “Remaining positions” line is

decremented - at this time rotate the receiver and place it on the

board by another side. Repeat until the number of remaining

positions is greater than zero.

After completing the calibration, please make sure that the total G-

Force displayed on the Telemetry screen lies in the range of 0.99 -

1.01G (measured at rest).

5.8 Vibration analysis

Vib ra ti on s are an u nd es ir ab le

phenomenon for any stabilization

system, as it adds unwanted noise into

measurement. In the receiver menu,

you can display a graph showing the

actual vibration level. It’s measured

using frequenc y ana lysi s in the

selected accelerometer axis.

The receiver itself contains effective algorithms to suppress the

vibrations (see Configuration -> Advanced Properties), but the

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cost is a relative reduction of the model's preciseness and

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maneuverability.

If the vibrations are too high (in the graph approximately over the

half of Y axis), we recommend taking some of the following

precautions to reduce them:

 Fix the receiver in the model with a soft double-sided adhesive

tape.

 Secure the cables leading to the receiver so they cannot move

arbitrarily in the model which could amplify the vibrations.

 Use a balanced propeller.

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6 Advanced properties

Output period - setting the output signal period (Auto setting can

be used to synchronize outputs with the transmitter). This

parameter fundamentally affects the behavior of the servos.

Setting lower output period leads the analogue servos to achieve

faster response and increases current consumption. Some types of

analogue servos may behave erratically if the value is set too low.

Number of PPM channels - Set the number of channels

encapsulated in the PPM serial stream. If the receiver gets fewer

channels than this setting, the remaining channels (in the

Computed mode) will be replaced by a default value specified in

the Fail-Safe position for each channel. Otherwise, the number of

output channels will be reduced to the set value.

PPM/UDI Mode - Defines how the transmitter data is processed.

You can choose from the following modes:

Direct - The PPM and UDI output signal contains data directly

- Conversions and eventual channel mapping are only

- Various settings for servo outputs and for PPM/UDI

Computed - Both servo outputs and PPM or UDI signals are

- Output pulses for servos and PPM/UDI contain the

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from the transmitter without any recalculation.

applied to servo outputs.

can be set.

recalculated and mapped.

same information, but neither PPM nor UDI carries

flight-stabilized data.

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Note: This option does not apply to EX Bus outputs. These are

always direct without receiver recalculation (if the function

"Stabilize EX Bus output" is not activated).

Stabilize EX Bus output - Check this option to ensure that flight

stabilization is applied to the EX Bus output. In such case, the serial

data will correspond directly to servo outputs. This mode is useful if

you are planning to use the REX A receiver with stabilization

enabled along with a Central Box 100/200/400.

Low Voltage Alarm - Used to set the decision level of the low

voltage alarm, which is indicated by the receiver itself. You can also

set the low voltage alarm directly in the DC/DS transmitter (Timers /

Sensors -> Alarms menu).

6.1 PID control setting

Aileron/Roll rate, Elevator/Pitch rate, Rudder/Yaw rate - In this

section you set the individual PID control coefficients for each axis

separately for multicopter models. These coefficients are applied in

all flight modes to stabilize the rotational speed around each axis.

Vertical Speed - PID coefficients to stabilize the climb and descent

rate.

Aileron/Roll angle, Elevator/Pitch angle, Rudder/Yaw angle -

Here you can change the proportional gain of attitude stabilization,

e.g. horizon. The higher the coefficients you specify, the faster the

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model is reoriented to the new attitude.

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6.2 “Stabilize” mode setting

Maximum roll angle - Defines the maximum possible tilt angle to

the left and right in the horizon stabilization mode (controlled by

aileron input).

Maximum pitch angle - Definition of the maximum possible tilt

angle in horizon stabilization mode (controlled by elevator input).

Minimum pitch angle - Definition of the minimum possible tilt

angle in horizon stabilization mode (controlled by elevator input).

PID transition delay - Used to switch between flight modes that

use stabilization with different gains of the PID coefficients. This

feature guarantees that the change of the coefficients does not

cause erratic behavior in flight.

Sensor trim (Roll/Pitch) – Using these parameters you can fine-

tune the receiver position in the model if its position is not

absolutely parallel to the axis of ailerons and the elevator. Sensor

trims are applied in the flight modes where the horizon is stabilized

and you can achieve, for example, with airplane models a slightly

pulled horizontal flight.

Quick trim setting: Place the model on a flat solid horizontal

surface so that its position exactly matches the horizontal flight (a

multicopter should be positioned exactly horizontally). Now in the

Receiver Configuration -> Advanced Settings -> activate the “Set

sensor trims now” command. The calculated values will be stored

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in receiver memory.

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6.3 Acro mode settings

Maximum Aileron/Roll rate, Maximum Elevator/Pitch rate,

Maximum Rudder/Yaw rate - Specifies the maximum angular

rotation speed in individual axes (in degrees per second) that can

be safely reached by the model. For acrobatic models, this value can

be up to two revolutions per second (720°/s), but for gliders it will

be noticeably smaller (e.g. 90°/s).

Aerobatics Factor (Roll/Pitch/Yaw stick priority) - Determines

how the stabilization gain will be decreases depending on how the

control stick moves away from the center position. For example, a

60% aileron stick priority means that at maximum left or right stick

position, the aileron gain will be reduced to 60% and the direct

position of the stick will be applied from 40%.

Throttle-PID Attenuation (TPA) – A function for multicopter

models, see Chapter 10, “Other stabilization features”.

Speed-PID Attenuation – A function for airplane models, see

Chapter 10, “Other Stabilization Functions”.

Dead Zone

Dead zone parameters indicate the size of the area around the

center position of the controls, where the resulting stick position in

the given direction is considered zero.

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6.4 Filtering

Low-Pass filter frequency - Here you enter the frequency of the

digital filter (in Herz units) to suppress vibration noise on the

gyroscope. Keep in mind that the lower the frequency you enter,

the less the model will be prone to vibration, but the accuracy and

speed of flight stabilization will be limited. The recommended

value is 10-20Hz for airplanes and 20-60Hz for multicopters.

PID Derivative Low-Pass filter - Here you enter the frequency of

the digital filter (in Herz units) to suppress noise of the derivative

component of the stabilization control loop. Recommended value

of 20Hz should be modified with caution.

Filter specific frequency - By enabling this option, you enable

advanced filtering to remove specific vibrations caused by motor

running. Adjust the average filter frequency and filter bandwidth

according to the vibration analysis graph.

Arming switch

The arming procedure is automatic for airplane models so that the

stabilization is enabled automatically after receiver initialization.

On the contrary, for multicopters, you must move the controls to

the extreme positions when the throttle is pulled low for arming.

Alternatively, you can assign a two-position switch on the DC/DS

transmitter to arm the stabilization and make the propellers spin.

This switch does not need to be assigned to any channel on the

transmitter - the arming command is sent separately as soon as you

confirm the dialog box that appears after activating the switch.

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6.5 Fail-Safe

Fail-Safe – Turns the Fail Safe function

on or off. If the function is disabled, no

pulses on the receiver outputs are

generated in case of signal loss. If this

func tion i s enabled, the receiver

outputs can be configured individually

with the following options:

 Hold - The receiver repeats the last known values on its output.

 Out OFF - the output pin is deactivated.

 Fail-Safe - the output is moved to a position given by the

parameter “Value” at a speed given by “Speed” parameter. You

can set the Fail-Safe positions either by editing each output

value separately or by simply moving the transmitter controls to

the required position and activating the “Set fail-safe position

now” command.

Fail-Safe Delay – Indicates the time interval from a moment the

receiver detects signal loss to when the fail-safe control throws are

initiated. After the expiration of this time, the receiver outputs will

transfer to preset defaults or will be turned off (according to

individual pin settings).

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7 Alternative pins configuration

Here you can change the modes of the

receiver pins. Servo outputs can be

configured, for example, in digital

input or digital output mode.

Servo - standard impulse output for

servo control (-100% ~ 1ms, 0% ~

1.5ms, + 100% ~ 2ms).

If the output pin is set to "Servo" mode, you can specify maximum

possible throws that will never be exceeded. These limits should be

adjusted to protect individual servos against overshots and model

damage.

Digital input - the logic value of a given signal pin (0 or 1) is

transferred to the transmitter in the form of EX telemetry (so it can

be further displayed and stored). Receiver pins are equipped with

internal pull-up resistors, so you can easily connect the signal wire

to the ground for logic level detection. It is not allowed to connect

external voltage to this pin.

Digital output - the receiver will discretize the channel value of the

given pin. If this value is greater than 1.5ms (>0%), the output pin

value will be logic “1”. Otherwise, the output value will be logic “0”.

Using this approach, you can control e.g. simple model lighting

made up of LEDs. In this mode, the Fail-Safe settings for the pin are

also applied.

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Motor 1-8 - for a multicopter model, this parameter is used to

identify individual motors (assignment is made automatically via

the Quick Wizard). Refresh rate of the motor outputs is 400Hz by

default, and conventional servo pulses or OneShot125 protocol can

be used for control.

Camera control (roll, tilting/pitch, and pan/yaw) - output pins

assignment for a stabilized camera gimbal controlled by servos.

PPM Positive Output - standard PPM signal with positive logic of

the PPM data stream. The idle state of the line is logic 0.

PPM Negative Output - standard PPM signal with inverse logic of

the PPM data stream. The idle state of the line is logic 1.

PPM Input - For a given receiver port, the PPM input signal from

another receiver is expected. This option is suitable if you want to

use a backup receiver with a PPM output stream.

JETIBOX/Sensor EX - connection of telemetry sensor or JETIBOX.

EX Bus - digital bidirectional communication for channels

transmission, telemetry and communication data. This setting is

suitable for example in connection with a Central Box or other EX

Bus-capable device.

Serial UDI12/16 - serial output suitable for connection of devices

with UDI support (Universal Data Interface, e.g. Vbar).

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REX 6A

REX 7A

REX 10A

REX 12A

Pin1

Y1Y1Y1

Pin2Y2Y2Y2Y2

Pin3

Y3Y3Y3

Pin4Y4Y4Y4Y4

Pin5

Y5/E1

Y5, LED Strip

Pin6

Y6/E2

Y6/E1Y6Y6

Pin7

Ext.

Y7/E2

Pin8

Ext.

Y8/E2

Pin9 Y9 Y9

Pin10

Y10

Pin11

Bat.

Y11

Pin12

Bat.

Y12, LED Strip

Pin13

Pin14

Ext.

LED Strip - A LED strip composed of programmable LED chips can

be connected to the dedicated pin of the receiver.

Table of possible functions on the individual receiver pins

Output types:

Y - servo output, digital output, digital input, motor 1-8 (multicopters),

camera roll, pitch, and yaw.

E1,2 - JETIB OX/EX sensor, PPM output, PPM input, EX Bus output, UDI

output

Ext. - JETI BOX/EX sensor

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7.1 Receiver Outputs

The receiver output settings screen allows you to redirect the

transmitter channels to any receiver output. For clarity, the

transmitter channels are described by their numerical value and

their meaning.

As the last parameter, you can set the output group (A-H) for each

servo separately. Assigning servo outputs to the same group means

that their control pulses will be generated at the same time. For the

100Hz mode, we recommend using only A-C groups. In addition,

please note that the servos belonging to the same function should

be ideally in the same group.

Note:

Channel redirection is applied to the received data before

stabilization processing, so after any change in the output pins

assignment, we recommend you to re-calibrate the ”Assist

channels in the Configuration -> Channels Assignment” menu.

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8 Real time telemetry

By default, the receiver provides

operational telemetry data such as

battery voltage and signal strength on

a scale from 0 to 9. With integrated

inertial sensors, it can also provide its

orientation in individual axes (roll,

pitch and yaw) or total G-force.

Up to 3 additional Duplex sensors can

be connected to the receiver. For this

purpose you can use the ports marked

Ext, E1 and E2 (the latter two must first

be switched to the role of telemetry

inputs).

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9 Solving the most common problems

9.1 General

1. After pairing the receiver, it is not possible to configure it

using the DC/DS transmitter. But the Device Explorer screen

displays the correct name (e.g. REX12A).

Check the transmitter version (minimum version supporting the

REX A receiver is 4.24). Also, make sure that in the Devices folder at

your transmitter contains files which match the receiver name and

it s langua ge version : “REX 12A .BI N”, “R X12 AEN .BI N”,

“RX12ACZ.BIN” etc. If these files are not located in the folder,

please download the latest configuration files for the receivers from

www.jetimodel.com. These files are also a standard part of the

transmitter update.

9.2 Airplane models

1. At high speed and straight flight, the model oscillates in one

of the axes (e.g. ailerons). Reduce the Gain value for that axis in

the receiver settings (Configuration - >Airplane Settings menu).

2. In Heading Hold mode, the model does not hold its direction.

Increase the Hold value for the elevator or rudder axis in the

receiver settings (Configuration -> Airplane Settings menu).

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3. In Heading Hold mode, the model does not hold a straight

flight and constantly turns to one side.

In this mode, it is not possible to use trims as they distort the input

information for stabilization. Switch to Normal mode (or deactivate

stabilization if necessary), trim the model in straight flight and land.

Now reassign the primary channels (Configuration -> Channel

Assignment menu).

4. When the stabilization is enabled, the surfaces do not return

to the center position even when the model is at rest for a

longer time.

In Heading Hold mode, the model remembers its original direction

before displacement and tries to return to that position. Therefore,

control surfaces may be out of neutral even when the model is at

rest. Switch stabilization to another mode (e.g. Normal or Manual).

5. Stabilization gain tuning channel for ailerons, or other axis,

cannot be assigned.

Please make sure that the stabilization gain tuning function has

been created on the transmitter and has been assigned to a free

channel (1-16). Stabilization gain control knob, or a three-way

stabilization flight mode switch (Off/Normal/Heading Hold) should

be added in the Model -> Functions Assignment menu in your

DC/DS transmitter. Subsequently select this function for a free

channel in the Model –> Servo Assignment menu. Now it is

possible to start the Quick Wizard in the receiver menu, where in

step 6 this three-position switch can be used.

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9.3 Multicopter models

1. The transmitter announces “Armed”, but the motors are not

spinning.

In the Configuration -> Multicopter Settings menu, be sure to pay

attention to the Minimum running throttle parameter. Increase the

value in small steps to make the motors spin after arming.

2. When at full throttle, the multicopter oscillates quickly, but

when the throttle is in the middle, the flight is calm.

We recommend enabling the “Throttle-PID Attenuation (TPA)”

function in the Configuration -> Advanced Properties menu. Set

the “TPA breakpoint” to a value before the oscillations start to

appear (e.g. 50%) and increase the “TPA value” by 10% increments.

3. Stabilization gain tuning channels for individual axes cannot

be assigned.

Please make sure that the stabilization gain tuning function has

been created on the transmitter and has been assigned to a free

channel (1-16). Stabilization gain control knob or a three-way

stabilization flight mode switch should be added in the Model ->

Functions Assignme nt menu in your DC/DS transmitter.

Subsequently select this function for a free channel in the Model –>

Servo Assignment menu. Now it is possible to start the Quick

Wizard in the receiver menu, where in step 6 this three-position

switch can be used.

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10 Receiver update and configuring

Duplex REX receivers can be

updated via PC with the aid of

the JETI USB adapter. You may

find a detailed description of

the receiver update process in

the USB adapter instruction

manual.

10.1 Update the receiver

USB adapter

REX A receivers can be updated and configured by PC via JETI USB

Adapter. The JETI Studio software can be used for updates – you can

download it from the manufacturer's website:

www.jetimodel.com

1. Unplug all devices (servos and sensors) from the receiver before

you begin the update.

2. Connect the USB Adapter to your computer.

3. Start JETI Studio and select the correct serial port for

communication.

4. Open the Device Updater dialog.

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5. Connect the receiver via its Ext. port to the USB Adapter.

6. The program identifies the connected device and offers an

appropriate update. Choose the firmware version and variant

and then click the Update button.

7. Once the update is completed, disconnect the receiver.

10.2 Configuring the receiver with a PC

Using the JETI Studio software, REX A receivers can also be

configured by the owners of Duplex Tx modules.

1. Connect the receiver via its Ext. port to the USB Adapter and

then to the computer. If the receiver is powered through a USB

Adapter, make sure that all servos are disconnected.

2. In JETI Studio, choose the Device Explorer tool. The receiver

should be detected and displayed after a moment. By double-

clicking you can now enter its configuration.

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ELECTROSTATIC SENSITIVE DEVICE

OBSERVE HANDLING PRECAUTIONS

For receivers we grant a warranty of 24 months from the day of

purchase under the assumption that they have been operated

in conformity with these instructions at recomm ended

voltages and that they were not damaged mechanically.

Warranty and post warranty service is provided by the

manufacturer.

We wish you sucessful flying with the products of:

JETI model s.r.o. Příbor, www.jetimodel.com

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THIS DEVICE COMPLIES WITH PART 15 OF THE FCC RULES.

O PE RAT ION IS S UB JEC T TO TH E FO LLO W IN G TWO

CONDITIONS(1) THIS DEVICE MAY NOT CAUSE HARMFUL

INTERFERENCE, AND (2) THIS DEVICE MUST ACCEPT ANY

INTERFERENCE RECEIVED, INCLUDING INTERFERENCE THAT

MAY CAUSE UNDESIRED OPERATION.

Warning: Changes or modifications to this device not expressly

approved by Esprit Model/JETI USA could void the user ’s authority to

operate the equipment. “This equipment complies with FCC radiation

expos ure limits set f orth for an uncontrolled environment. This

equipment is in direct contact with the body of the user under normal

operating conditions. This transmitter must not be co-located or

operating in conjunction with any other antenna or transmitter.”

Under Industr y Canada regulations, this radio transmitter may only

operate using an antenna of a type and maximum (or lesser) gain

approved for the transmitter by Industry Canada. To reduce potential

radio interference to other users, the antenna type and its gain should

be so chosen that the equivalent isotropically radiated power (e.i.r.p.) is

not more than that necessary for successful communication.

Conformément à la réglementation d'Industrie Canada, le présent

émetteur radio peut fonctionner avec une antenne d'un type et d'un

gain maximal (ou inférieur) approuvé pour l'émetteur par Industrie

Ca na da . D ans l e b ut de rédu ir e les ri sq ues de br ou illa ge

radioélectrique à l'intention des autres utilisateurs, il faut choisir le

type d'antenne et son gain de sorte que la puissance isotrope rayonnée

éq uiva len te ( p.i. r.e. ) ne dép ass e pa s l' intensit é né ces saire à

l'ét ablisse ment d' une communica tion satisfa isante. This device

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complies with the Industry Canada license-exempt RSS standard(s).

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Operation is subject to the following two conditions: (1) this device

may not cause interference, and (2) this device must accept any

interf erence, in cluding inter feren ce tha t may cause undesi red

operation of the device. Le présent appareil est conforme aux CNR

d'Ind ustrie Canada a pplicables aux apparei ls radio exempts de

licence. L'exploitation est autorisée aux deux conditions suivantes : (1)

l'appareil ne doit pas produire de brouillage, et (2) l'utilisateur de

l'appareil doit accepter tout brouillage radioélectrique subi, même si le

brouillage est susceptible d'en compromettre le fonctionnement.

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Duplex-System EX:

• Transmitter modules

• Receivers

• Telemetric sensors

• Compatible accessories

• Display units

Serial number:

Carefully save this serial number!

JETI model s.r.o.

Lomená 1530, 742 58 Příbor

Czech Republic - EU

www.jetimodel.com

www.jetimodel.de

info@jetimodel.cz

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