In order to facilitate data communication between external devices or intelligent instruments equipped with different standard serial interfaces, standard serial interfaces must be converted to each other. The HESC-T-002 serial converter can convert the RS-232C data transmission (TXD) and data reception (RXD) signals into TTL/COMS compatible levels. The converted TTL level is 0-3.3V without the external power supply. This converter adopts a unique "RS-232 charge pump driver", which does not need to initialize the RS-232 serial port to obtain power. It has zero-delay automatic transceiver conversion internally, and a unique I/O circuit automatically controls the direction of data flow without the need for handshake signals (such as RTS, DTR, etc.). All of these makes sure that RS-232 programs written in full-duplex mode can run in TTL mode without modification, suitable for existing operating software and interface hardware. This series converters provide baud rate from 300 bps to 115,200 bps.