Documentation/QE3 Screen Remote Controller WikiEnglish · V1
Browse documentation
Data Link Module Expansion and Recommendations

Data Link Expansion Overview

QE3 data links are mainly divided into two categories:

7 min read · English documentation

QE3 data links are mainly divided into two categories:

  • Built-in data link (factory customization)
    The complete unit is integrated and calibrated before leaving the factory. Therefore, the selected package necessarily includes the station unit for a specific data link model.
  • External data link module (connected through the expansion bay and must support SBUS)
    A third-party or subsequently added data link module is connected through the expansion bay at the rear of the unit.

The product provides only the necessary interface definition information (for details, see 7.1.3 Introduction to the External Data Link Module (Expansion Bay)) and basic product-use consultation. Because DIY work is inherently uncertain and risky, our company does not provide detailed instructions on how to perform DIY modifications;

Our company still provides project customization or OEM services for customers who need to integrate their own data link while retaining complete-unit after-sales service for the external data link.

At the system level, both solutions share the following capabilities:

  • A unified local display and control interface;
  • Configuration of link, frequency-band, channel, bandwidth, and other parameters according to the corresponding data link manual;
  • Physical connections through the interfaces and expansion capabilities described in the Technical Parameters chapter.

Typical Configuration

  • The data link module is configured and delivered with the complete unit and supports only specified model/payload combinations;
  • RF routing, antenna layout, power supply, and heat dissipation are completed at the factory, with no secondary modification required by the user;
  • Control protocols (such as remote-control signals, telemetry, and video streams) have been integrated and tested with the flight controller/host computer.

Use and Maintenance Notes

  • Complete initial pairing according to “Common Software Downloads and Installation” in Quick Start;
  • During routine use, pay particular attention to link-quality indicators, warning messages, and the restrictions on transmit power and frequency bands in Chapter 2, Safety and Compliance;
  • Firmware upgrades or migration to a new-generation built-in data link solution are generally completed through complete-unit firmware upgrades or project-level redesign, rather than by users replacing the module themselves.

To evaluate the bandwidth, latency, and interference resistance of the built-in data link, refer to both the data link module specifications supplied with the project and Section 6.3, “Communication and Data Link Capabilities.”

c10fb0c850c576800ffbccc83a286040_compress.jpg

Interface dimensions diagram

292c8f9acb1738fb1f08b03424d2d434.jpg

Interface pinout diagram

QE3 has an expansion bay and RF interfaces reserved inside the unit. Typical features include:

  • A reserved power interface (voltage/current capacity: 12V1A);
  • Reserved data interfaces on the main controller (such as serial ports, Ethernet, SBUS, and USB);
  • Several pre-installed RF feeder cables ( IPEX1), allowing the external data link module's antennas to be routed outside the unit's enclosure.

The specific expansion-bay dimensions, mounting-hole locations, power supply, and interface definitions are subject to the project-level technical specifications. This section provides only general principles.

  • Use a customized COFDM/OFDM HD data link module, secure it in the expansion bay, and power it from QE3;
  • Replace the data link module with one using a different frequency band (such as 1.4GHz / 5.8GHz) or power level to comply with regulations in different countries and accommodate different mission radii;
  • Connect a third-party industrial integrated data link unit to achieve cross-platform compatibility.

The following is a general engineering process. In an actual project, follow the data link module's technical documentation and the project-level validation plan.

  1. Clarify requirements
    • Define the target frequency band, transmit power, modulation scheme, expected range, and bandwidth;
    • Determine whether a bidirectional data link (telemetry + control) or video downlink only is required.
  2. Confirm interfaces and power supply
    • Check the voltage/current capacity available from the QE3 expansion bay and assess whether it meets the data link module's power requirements;
    • Confirm the physical and protocol compatibility of the data interfaces (serial port / Ethernet / USB, etc.).
  3. Mechanical and RF integration
    • Design a mounting bracket or adapter plate based on the mounting-hole locations and height of the expansion bay;
    • Use RF feeder cables of an appropriate length and specification (such as IPEX1), avoiding excessive length that could cause attenuation or a bend radius that is too small;
    • Plan antenna mounting locations to avoid metal obstructions and strong sources of interference.
  4. System integration testing
    • Complete pairing, video-image, and latency tests in a test environment;
    • Verify that link packet loss, reconnection logic, warning messages, and UI behavior meet the requirements;
    • Adjust parameters such as frequency band, bandwidth, and bit rate based on the test results.
  5. Safety and compliance checks
    • Verify that the transmit power and frequency band comply with local radio regulations;
    • Add project-level safety instructions and use restrictions within the framework of Chapter 2, “Safety and Compliance.”

Notes and FAQs

If an external data link fails to connect to QGroundControl (QGC) or cannot establish a session, a common cause is an incorrect serial-port/data link configuration. For example, if the mobile unit is configured to transmit only, telemetry or control data cannot be sent back, and QGC cannot complete the handshake. Refer to the instructions for the data link module and flight controller to confirm that the serial-port role is bidirectional (transmit and receive), that the baud rate and protocol match, and that both ends support and have enabled the required data directions.

If QGC reports an error after the built-in data link connects and takeoff is not possible, restart the built-in data link and reconnect it. If the cable connections and data link configuration are correct but normal flight remains impossible after multiple connection attempts, contact ROBOSN technical support.

Relationship to Other Chapters

  • Chapter 1, Product Overview: Provides a high-level highlight of “data link expansion capabilities,” forming an “overview + details” relationship with this section;
  • Chapter 5, Remote Assistant - System Function Settings: “Network and Communication Settings - System Settings” covers link parameters and network configuration, while “Button and Channel Configuration” can be used to inspect and monitor channel behavior on the remote-controller side;
  • Chapter 6, Technical Parameters: Provides performance metrics and interface specifications through sections such as “Communication and Data Link Capabilities” and “Interface and Expansion Capabilities”;
  • Chapter 9, Troubleshooting and Support: Can be supplemented with FAQs and troubleshooting recommendations for different data link modules.

Note: The external data link supports a maximum power of 24 W; 12 V, 1 A is recommended.
Caution: When the remote controller's battery level is below 10%, it cannot switch to the external data link.

RSSI LED Status Integration Protocol (Advanced)

To support signal-strength displays for different data link devices, the system provides a UDP-based RSSI LED protocol interface. Its typical characteristics are as follows (for reference by data link/system engineers):

  • Transport: UDP
  • Port: 55555
  • TYPE field: RSSI_LED, value 0x09, data-field length LEN = 12
  • Data: RGB brightness values for 4 groups of indicators in the following order, for a total of 12 bytes:
    • LED1_R, LED1_G, LED1_B
    • LED2_R, LED2_G, LED2_B
    • LED3_R, LED3_G, LED3_B
    • LED4_R, LED4_G, LED4_B
  • Value range for each channel: 0 ~ 255. A maximum brightness of approximately 50 or lower is recommended to prevent excessive brightness from affecting the viewing experience.

The basic structure of a protocol packet is as follows:

  • Frame header: HEAD1 = 0x5A, HEAD2 = 0xA5
  • TYPE: 0x09 (RSSI_LED)
  • LEN: 12 (data-field length)
  • DATA: the 12 bytes of RGB values described above
  • CRC: 1-byte checksum (refer to the accompanying engineering documentation for the specific calculation method)

Data link manufacturers can map their RSSI percentage or level scheme to the corresponding RGB combinations and periodically send them to port 55555 according to the protocol above. This drives the RSSI indicators on the QE3 front panel to provide multilevel brightness/color indications.