Quelltext der Seite WSAL20655 – 2-CH UART TO ETH/en

__NOINDEX__
'''Documentation notice:''' This technical documentation was independently rewritten from an archived supplier source. Check technical details and commands against the product version and manufacturer documentation before use.

== Summary ==
The Waveshare 2-CH UART TO ETH module links two serial TTL interfaces to a 10/100 Mbps Ethernet port via the CH9121 chip. It supports four operating modes — TCP client, TCP server, UDP client and UDP server — as well as bidirectional transparent transmission between UART and Ethernet.

== Related products at JW Tech ==
* [https://shop.jw-tech.eu/p/WSAL20655 WSAL20655 – 2-CH UART To Ethernet Converter, Serial Port Transparent Transmission Module]

== Technical overview ==
* Operating voltage 3.3 V or 5 V; typical current draw about 140 mA.
* Two independent UART channels: channel 1 is enabled by default, channel 2 is disabled by default.
* Ethernet: 10/100 Mbps full/half-duplex with auto-negotiation, 802.3-compliant, automatic MDI/MDIX detection.
* Four network operating modes: TCP CLIENT, TCP SERVER, UDP CLIENT, UDP SERVER.
* Default values: IP 192.168.1.200, subnet mask 255.255.255.0, gateway 192.168.1.1, device port 2000, target IP 192.168.1.100, target port 1000.
* UART1 defaults: 9600 baud, 8 data bits, 1 stop bit, no parity, timeout 0, buffer never cleared.
* Pins: 5V/3V3, GND, RST1 (external reset, low active), RESET (factory settings on power-on, low active), TXD1/RXD1 (enabled), TXD2/RXD2 (disabled), CFG0 (low enters configuration mode), RUN (status indicator), DIR1/DIR2 (RS485 RX/TX switching).
* Configuration is done via the PC software NetModuleConfig.exe or through serial commands; stored parameters are restored after a reboot.
* The CH9121 stores its configuration in internal memory; after a reset the chip operates according to the saved values.
* Demo projects for microcontrollers such as Raspberry Pi Pico, Arduino or STM32 are provided in C and Python; connections use the respective GPIO pins.

'''Commands and examples – verify before use:''' 
<syntaxhighlight lang="text">
sudo apt-get install p7zip-full
sudo wget https://files.waveshare.com/upload/3/37/2-CH_UART_TO_ETH_CODE.7z
7z x Pico_ETH_CH9121_CODE.7z -o./2-CH UART TO ETH_CODE
cmake ..
make -j9
cp main.uf2 /media/pi/RPI-RP2/
</syntaxhighlight>

== Notes and version constraints ==
* The listed default IP values are factory presets; before deployment in your own network, the IP configuration must be adapted to the local subnet.
* The demo files must be downloaded and extracted; the exact Pico firmware version (rp2-pico-20210418-v1.15.uf2) is version-sensitive.
* When flashing the Pico over USB, the BOOTSET button must be held until the drive is recognized — otherwise the firmware will not be written.
* When using RS485, the DIR1/DIR2 pins must be connected to an external RS485 control circuit; without it, the automatic switching remains unused.
* The Thonny version must be up to date, because older versions may lack the Pico support package.
* Before production operation, packet loss at higher baud rates should be tested.

== Source and revision record ==
* [https://www.waveshare.com/wiki/2-CH_UART_TO_ETH 2-CH UART TO ETH - Waveshare Wiki]
* Source revision: 102648
* Captured: 2026-09-02T04:08:37+00:00
* SHA-256: <code>0590b7c8e72e86009bb912160691ccb362ab76f109664387400464f027ba38e0</code>