ICS ELECTRONICS 4863 Manual page 154

Functionally, the specification established two types of devices, DCE
and DTE, that would mate together by a pin-to-pin cable. The Data
Communication Equipment (DCE) was designated as the device that
connected to the communication line. An example of a DCE is a
modem. The Data Terminal Equipment (DTE) was designated as the
device that connected to the DCE. Examples of a DTE are a PC
computer or a terminal. DTE devices can be mated to DTE devices
by a special 'null-modem' cable that crosses the transmit signals of one
device with the receive signals on the other device.
In Europe, the Comite Constultatif International Telephonique it
Telegraphiqe (CCITT) has established standards that correspond to
RS-232C. While these standards, CCITT V.24 and CCITT V.28, are
very similar to RS-232C, they are not identical. The Model 4984
conforms to both RS-232 and CCITT V.24 standards, but does not
contain or use all of the circuits allowed for in both standards.
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