Serial Data Communications

The "electronic brains" behind the data message is a dedicated silicon chip known as "Universal Asynchronous Receiver / Transmitter (UART). This chip is an interface between the parallel bus communications internal device and the serial port (' Com '). Some UART chips are able to cache large amounts of data from the computer bus while transmitting to serial ports at speeds up to 115 kbps approx.

The serial port connectors in use today contain 9 or 25-pin, with the pin assignment indicating a younger age modem for connection to the computer. The legacy of having dedicated pins for the transmission, reception and other control functions, allows serial data transmit and receive simultaneously, ie full duplex.

Naturally, the bidirectional communication is a great benefit, but only if the transmitter and the receiver can optimize the amount of data transmitted and the time intervals in which this is done. This important feature is known as "flow control" and is implemented by having a device to tell the other when and when not sending data, as in most USB to RS485 or RS232 RS485 converters.

In the world of communication specific hardware serial pins assigned to this function are: Data Terminal Ready (DTR) and Data Set Ready (DSR), Request To Send (RTS) and Clear To Send (CTS). By controlling these lines the device connected to the computer can react to a surge of data (beyond its cache to handle) by reducing the 'Clear To Send "(CTS) Pin Signal, knowing that their control CTS pin computer see the signal drops, and stop sending data.