DB9-SP space saving connector RS-232C data interface fully compatible with PC DB9 connector and 4-bit terminal are optional to RS-485 interface Automatic direction control of transmitting data (TXD), zero-latency design Working mode: asynchronous half or full duplex High efficiency serial port electricity stealing technology, need no external power supply, real three line (TD, RD, GND) mode communication Communication speed: 0-115.