transmit data (interface line) (TxD)
Transmit Data (TxD) and Receive Data(RxD) are interface lines for transmit and receive data. The transmit and receive data are transmitted between a data transmission device( DCE) and a data terminalequipment( DTE) via these interface lines.
The transmission of the send data can take place both from the data transmission device to the data terminal device and in the reverse direction, for example in both directions between a modem and a personal computer.
Corresponding interfaces with TxD lines are X.21 and V.24, resp. RS-232-C. In the 9- pin Sub-D connector of RS-232-C, pin 3 is occupied by the TxD signal, in the 25-pin it is pin 2.