Foxtech D04 User manual

D04
Multi-link Signal Relay

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Contents
Disclaimer.....................................................................................................................3
Product Introduction....................................................................................................5
Packing List................................................................................................................... 6
Product instructions.....................................................................................................7
Radio Power On and Off.............................................................................................. 9
Status Indicator Instructions......................................................................................10
Ground Unit Indicator.................................................................................10
Receiver Indicator....................................................................................... 11
Ground Unit and PC Communication........................................................................ 12
Wireless network selection and setup...................................................................... 13
WIFI Wireless Network Connection............................................................13
BLE Wireless Network Connection............................................................. 15
Datalink Link Communication Test.............................................................................20
Radio Parameter Configuration................................................................................. 21
Ground Unit Battery Charging................................................................................... 26
Radio Alarm................................................................................................................27
Failsafe Setting........................................................................................................... 28
WiFI Module Parameter Setting................................................................................ 29
BLE Module Parameter Setting...................................................................34
BLE and WIFI Modules are Restored to Factory Settings........................... 36
Check the Radio System Firmware Version............................................................... 37
Firmware Upgrade Steps............................................................................................38
Ground unit Firmware upgrade..................................................................38
Receiver firmware upgrade........................................................................ 41
FAQ............................................................................................................................. 43

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Disclaimer
Thank you for purchasing the D04 Dual Link Radio (hereafter referred to as "D04").
Please use D04 according to local radio regulations. Please read this statement
carefully before using it. Once used, it is deemed to be an endorsement and
acceptance of the entire contents of this statement. Please strictly follow the
instructions to install and use the product. FOXTECH Co., Ltd. will not assume any
legal responsibility for any result or loss caused by improper use, installation,
assembly and modification of the user.
Product Note:
1. D04 is used as the ground end (hereinafter referred to as "ground end") in
conjunction with the sky end R20 (hereinafter referred to as "sky end" or "airborne
end").
2. Built-in 12V battery on the ground (18s battery for 3s), external power input
DC7.4 - 12V (lithium battery 2s - 3s), please supply power to the radio in strict
accordance with the specifications.
3. Be sure to install the antenna before powering up to avoid damage to the circuit.
4. Ensure that the antenna is obstructed during the use of the antenna, without
bending, and as far as possible away from the large metal structural parts, to avoid
communication obstruction due to the above reasons.
5. Do not disassemble or modify it without permission. If you encounter problems
that cannot be solved during installation or use, please contact Huazhiyi or your
agent.
6. Pay attention to keep the proper distance between the electronic devices during
installation to minimize electromagnetic interference between devices.
7. Make sure all connections are securely fastened and all parts are working
properly before use.
8. Please check the surrounding environment before use to ensure that there is no
interference from other 840MHZ-930MHZ equipment, otherwise the radio data
transmission may be seriously affected.

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9. For better service customers, we have been optimizing the product upgrade. The
matching software and firmware of the product will be updated and updated from
time to time. There may be incompatibility between different firmware versions on
the ground and onboard. So please pay attention to check the software firmware
version when using. Please also pay attention to our website to get the latest
software firmware and technical support.
10. The software, firmware, drivers, port conversion tools, etc. involved in this
manual will be updated from time to time on our website. Please visit our website
to download it yourself or contact customer service.

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Product Introduction
The D04 is a multi-link signal relay system that can simultaneously transmit up to
two independent S-BUS data and one serial port data. By using D04 signal relay
The remote control signal can be enhanced and transmitted to the air unit together
with the TTL signal.So D04 Multi-link Signal Relay solves the problem of short
transmission distance of the remote controller and datalink. D04 features small size,
good integration and high sensitivity. The ground unit is integrated with wireless
network module (WIFI or BLE can be selected according to requirements), so users
can connect to RB20W ground unit by wireless network or USB data cable.
The wireless network can reach a stable coverage of 30~50M without interference.
D04 signal relay works in 840MHZ~915HZ frequency band and the maximum
communication distance is up to 30KM.

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Packing List
Main Module
Accessories
Cahrger×1
USB cable×1
Power cable×1
Parameter setting
For ground unit
For parameter
setting
For air unit
（DC:7.4-12V)
For air unit
Ground Unit ×1
Air Unit x 1

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Product instructions
D04 can simultaneously transmit up to two independent S-BUS data and one serial
port data. There are two ways to access the serial port data on the ground. One is
to input directly through the USB data line, and the other is to transmit through the
WIFI or BLE wireless network. When D04 detects the USB data cable insertion, it
uses USB to transmit the serial port data preferentially. When it is detected that the
USB data cable is not inserted, D04 automatically switches to your preset wireless
module (WIFI or BLE) to transmit the serial port data. If your remote control or
receiver does not support S-BUS, you will need to purchase a separate PWM to
S-BUS module.
Ground Unit
1Power indicator and button PWR
24 power indicator 25% ，50%， 75%， 100%
3Config indicator
2 S-BUS signal input，or config type
4Charge port
Support only DC 12.6V input
5Antenna interface

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SMA
6SET button
For parameter setting
7USB port Type-C
For parameter setting or data transmission, not batter charge port
8Data transmission module signal indicator
Indicator RS1 RS2 RS3 is the signal strength indicator. The number of lights indicates the strength of the
signal quality of the high-frequency data transmission module. It can also be used to indicate the type of
wireless network configuration in the configuration mode.
9wireless network connection status indicator nLink
The indicator light indicates that the wireless network is connected or transmitting data, and the indicator is off
indicating that the wireless network is not connected or is not transmitting data.
10 Working status indicator of wireless network nReady
When the indicator is on, the wireless module is working properly and can connect and transfer data.
Ground unit connection
diagram

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Radio Power On and Off
1. After pressing the power button PWR, the power indicator lights up and the four
battery indicator lights start to flash simultaneously.
2. During the period when the battery indicator flashes (about 5S), release the
power button and press and hold the power button again. At this time, the four
battery indicators will light up in the way of the water lamp until the buzzer sounds
long. Indicates that the boot action is complete.
3. The shutdown operation is the same as the startup operation. The flow direction
indication is different from the startup only when the button is pressed for a long
time.

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Status Indicator Instructions
Ground Unit Indicator
Indicator
status
implication
RS1,RS2,RS3 Configuration
mode
RS1 flash，RS2 和 RS3 go out
current wireless mode is WIFI
RS 1and RS2 flash， RS3 go out
current wireless mode is BLE
RS1,RS2,RS3 status before
turned on
RS1 is on，RS2and RS3 go out
current wireless mode is WIFI
RS 1and RS2 are on， RS3 goes out
current wireless mode is BLE
RS1,RS2,RS3working status
RS1,RS2,RS3 are on
High frequency module signal is strong
RS 1and RS2 is on，RS3 go out
High frequency module signal is general
RS1 is on，RS2and RS3 goes out
High frequency module signal is weak
Config
Always being on
In high frequency module config. mode
Go out
SBUS1 and SBUS2 no signal input
One flash a time
SBUS1 has signal input
Two flashes a time
SBUS2 has signal input
Quich flashing
SBUS1 and SBUS2 has signal input
PWR power indicator
flash
Firmware upgrade status in configuration mode
flash， with short continuous sound of
buzzer
Low voltage alarm
Always being on
Radio is powered on，in normal working status
Go out
Radio is powered off
4 power capacity indicator
25% flash， other 3 go out
LOW BATTERY less than 25%
25% flash，other 3 go out
Power during 25%～50%
25% and 50% is on ，other 2go out
Power during 50%～75%
25%、50% and 75% on，100% goes out
during 75%～100%
25%、50%、75%和 100% all are on
Fully charged 100%
All 4 flash， with short continuous
sound of buzzer
High temperature protection status

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nReady
on
The wireless module works normally and forms
a wireless network
off
The wireless module does not work properly
and does not form a wireless network
nLink
On
Wireless network data transmission is normal
off
Wireless network data transmission is abnormal
4 battery indicator lights from full-on state to full-off. After 5S, the
nReady indicator lights off first and then lights up.
The wireless module restored factory Settings
successfully
Receiver Indicator
indicator
status
implication
L1 灯
off
SBUS1 and SBUS2 no signal transmission
One flash a time
SBUS1 has signal transmission
One flash a time
SBUS2 has signal transmission
Quick flashing
SBUS1 and SBUS2 has signal transmission
L2 灯
Always being on
The receiver is in high frequency configuration
mode with no power output
L1、L2 always being on at the same time
The receiver is in firmware upgrade mode
RXD 灯
flash
Receiver has data reception
TXD 灯
flash
Receiver has data re-transmit
S1、S2、S3all on
Strong signal quality
S1 off，S2 and S3 on
Middle level of signal quality
S1 and S2 off，S3 flashes
weak signal quality

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Ground Unit and PC Communication
The communication between the ground terminal and the host computer uses the
USB data cable by default. If the USB data cable is not connected, the radio station
will automatically switch to the preset wireless module (WIFI or BLE) to transmit
the serial port data.
Ground terminal USB port
identification
After the radio is turned on, connect the radio and PC with the USB cable. If the
USB to serial port driver has been properly installed, the PC will display a port as
shown. If a yellow exclamation mark is displayed, the driver is not installed
correctly. Please go to our website to download the relevant driver.

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Wireless network selection and setup
Press and hold the set button during the boot process until the RSSI indicator RS1
flashes or RS1 and RS2 flash simultaneously, indicating that the wireless network
switching and configuration mode is entered. At this time, release the set button to
set the wireless module parameters and switch the wireless network through the
serial port AT command. For the WIFI module and Bluetooth module parameter
settings, please check the WIFI and Bluetooth parameter configuration chapters.
The following describes the switching of the wireless network, the specific method
is as follows:
Short press the PWR button to switch the wireless network. The number of flashing
RS1, RS2, and RS3 indicators indicates the wireless network type. The RS1 flashing
indicates that the current switch is WIFI, and the WIFI parameter can be set through
the USB data cable by using the serial AT command. RS1 and RS2 flash
simultaneously to indicate that the current switch is BLE, and the BLE parameter can
be set through the USB data line using the serial AT command. After the setting is
completed, press the set button to exit the setting.
WIFI Wireless Network Connection
The PC and the radio are not connected by the USB data cable, if the wireless
network selects the WIFI network, the WIFI network can be used for the serial
port link data transmission. The first time connecting to the WIFI network, you
need to connect manually. After selecting the automatic connection, as long
as the PC is within the range of the radio WIFI network, it will automatically
connect and can directly use the WiFi network communication.

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(1) Open the PC wireless network connection. If the radio WIFI module
works normally, it will scan the network named “D04_Radio”. The factory
default password is 88888888.
（2）After connecting to the WIFI network, the serial port link data
transmission can be performed through the TCP protocol or the virtual port
(requires WIFI virtual port tool).
11 If using TCP protocol for communication, open the Mission Planner
ground station, select TCP communication mode, input the radio IP
address 192.168.6.1, port number (default is 8899), establish connection
(the baud rate is not selected),

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2To use the port for communication, you need to use the WIFI virtual port
tool to virtualize the WIFI network connection into a port.
Install WIFI virtual port toolkit, click “Add”, then you will see the virtual
serial interface , select an unused port, the network protocol selects the
client, and input the datalink IP and port, click OK and you will see that a
new port ELTIMA Virtural Serial Port has been added to the device
manager. This port is the virtual serial port of the WIFI network.
BLE Wireless Network Connection
In the case where the PC and the radio are not connected by the USB data
cable, if the wireless network selects the BLE network, the BLE network can be
used for the data transmission. The first time you connect to a BLE network,
you need to add and identify devices. After the first connection of the radio
BLE and the PC, as long as the PC is within the range of the radio network, it
will automatically connect and can communicate directly using the BLE
network port.

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1. Select a PC with BLE function, open the network connection settings, and
enable the Bluetooth network connection.
2.
Open the device and printer options on the control panel and click Add
Device. If the radio BLE module works normally, the device “D04_Radio”
will be displayed in the device list, which is the Radio BLE device.
3. After the device is added, the PC will automatically install the BLE virtual
port driver. When you open the device manager, you can see that there
are two new Bluetooth link standard serial ports on the PC. In general, the
first port is the port we want to use.

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Air Unit
1Power port
support the XT30 connector，voltage：7.4-12V
2COM port
TTL port , used to connect the FC COM port or API.
3S-BUS1 port
Use the servo wire to connect the S-BUS interface of the flight controller or other equipment
4S-BUS2 Port
1
②
③
④
⑤
⑥
⑦
⑧
⑨

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5Use the servo wire to connect the S-BUS interface of the flight controller or other equipment
6Signal strength
S1 S2 S3- signal strength indicator
7High frequency module data transmission indicator
When RXD indicator is on, indicates that the receiver receives the data，TXD indicator is on means that the receiver
transmits data.
8S-BUS data indicator L1
used to indicate the communication status of S-bus signal between the ground
and air unit, and also indicate the button response while setting the Failsafe.
9Station configuration mode indicator L2
Used to indicate whether the receiver is in the configuration mode or the
communication status of the serial port signal, and also indicates the button
response while setting the failsafe.
10 SET Button
For firmware upgrade and parameter setting.
Air Unit Diagram
1. Tighten the antenna to the SMA connector.
2. Fixed the air unit on the drone.
3. Connect the COM port and S-BUS on the air unit to your device using the
servo cable as shown above.

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RX
TX
S
S
receiver GND
GND FC
receiver +
+ FC
TX
RX
-
-
4. input stable 7.4-12V DC power.

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Datalink Link Communication Test
After the connection is completed, please check the connection status by following
the steps below. (This step will be partially different due to the connection method
of the ground unit or the flight control)
1. If the ground unit is connected to PC by USB data cable , open the device
manager of the PC and check if the port is correctly identified. If you are using
Bluetooth or WIFI wireless connection, please ignore this step.
2. Check whether the two-way S-BUS on the ground unit has signal input, check
whether the air unit flight control serial port is normally connected, and
whether the flight control enters a stable working state.
3. Open the flight control ground station software, select the corresponding
COM port, and the baud rate to connect flight control (connect by using BLE or
WIFI, the baud rate can be free, according to the specific situation). The flight
control is normally connected, indicating that the datalink has been connected.
If the connection fails, please check the following points:
1)Whether the baud rate of the flight control, air unit and ground unit is the
same. If the ground unit is connected by USB data cable, the ground station's
baud rate should also be the same. If the ground unit is connected through
WIFI, the baud rate of the wireless module must be the same.
2)If the ground unit is connected by a USB cable, make sure that the driver of
the ground unit is successfully installed.
3)Use the parameter setting software to ensure that all parameter settings on
the ground and sky are consistent.
4)Make sure that the RX of the flight control is connected to the air unit TX
port, and the TX of the flight control to the air unit RX port.
4. Open the remote control setting interface in the ground station to check
whether the remote control data is normal. For example, the remote control
data changes normally with the joystick, it means that the remote control link
is connected. If the remote control is not normally connected, please check if
the "-, +, signal" of the S-BUS is reversed.
5. After the ground and the air unit are activated, if the 3 signal strength indicator
RS1 RS2 RS3 of ground unit and the signal strength indicator RS1 RS2 of the
air unit are always on, and the air unit signal strength indicator S3 flashes, it
means that the two modules have normally connected.