Two types of serial devices are available: Data Terminal Equipment and Data Communication Equipment. DTE devices are normally the source or destination devices, while DCE devices normally connect the source and destination together. Common examples of DTE equipment are terminals and printers, while the most common example of a DCE device is a modem.
The main difference between the two, as far as we are concerned, is that they transmit and receive data on different pins, as shown in Table 14.2.
The RS-232 specification is titled “Interface Between Data Terminal Equipment and Data Circuit-Terminating Equipment Employing Serial Binary Data Interchange,” ...