Description Helps to connect TTL level signals Compatible with RS232 interface Suitable for use with most microcontrollers 300 to 115200 bauds The DFRobot RS232 to TTLĀ Adapter helps to connect TTL (Transistor-Transistor Logic) level signals to RS232 interface. View more Specifications 4 pin connector - GND, Logic out (STX), +5v, Logic In (SRX)