How to change RS232 to TTL of wireless video data link modem

Modify the built-in conversion board of TX900 to change RS232 to TTL (UART)

The wireless video data link modem default is TTL. Which is the core module of TX900, which is a long-range wireless video transmitter and receiver.

If the client does not have a specific requirement, the default data port of TX900 is RS232.

The flight control, Pixhawk, and the data port need TTL.

So how do we change the RS232 to TTL of the long-range wireless video data transmitter and receiver?

Please open the metal of the TX900, you will find the board like the one below.
The left side is TTL, there are more 6pcs zero resistors and no two chipsets.
The right side is RS232, there are more two chipsets and no 6pca zero resistors.

TX900’s Sbus in connects to the remote controller on the ground.
TX900’s Sbus out connects to the flight controller in the air.

New RS232 to TTL data interface adapter board

If your order was shipped recently and the TX900 is equipped with our updated and optimized adapter board, please follow this method.

Please check the screenshot below. If you want to change the D3 serial port to TTL level, remove R1, R2, R20, and R22, and solder 22 ohm resistors (or 0 ohm) to R13 and R15.

Modify RS232 to TTL (UART) by adding an external adapter board

Change RS232 to RS485

Because of the small size of the tx900, it is difficult to directly convert the RS232 to the RS485 module internally. If you need the RS485 data interface, we can add a converter box outside the box as shown in the picture below:

TX900 Data Port Define Suggestion

Customers who use the sbus interface basically connect to drones; in addition to using the sbus interface, this type of demand also requires connecting to the flight control’s telemetry interface TTL. At present, customers prefer to connect to the telemetry interface through a serial to network connection. D1 cannot be used for sbus or serial to network connection, so only the D3 serial port can be connected to the flight control’s telemetry port. Therefore, for customers who need an sbus interface, it is recommended that D2 be used for sbus, D3 use TTL level, and D1 is up to the customer.