NOYITO RS422 to TTL UART MCU Serial Port Signal Mutual Conversion Module with Over-voltage Over-current Protection (3.3V)

I bought a few of these moduals for a project that needed to transmit data in a noisy environment. After I attached the modual using the labels on the board, nothing worked. The TX light lit up as the data was sent, but the RX light on the other end never lit up. Only after hours of testing, buying additional moduals, and more testing did I realize that the labels on the board are wrong. TXD is not transmit, it is receive, and RXD is not receive, it is transmit. Even the indicator LEDs are labeled wrong. After switching the wires around, it worked fantastically, but I can't get back the hours spent testing the chips due to a simple labeling mistake. I hope this helps anyone who is having issues with this device and others like it.

This does not work over any serious length of cable, which is the main selling point of RS422/RS485. It uses the 3.3v voltage it receives to attempt to make a "faux" RS422 signal. If your going next to higher voltage or down any length of cable, just don't bother. Buy a different converter and save the trouble.