DTE – Data Terminal Equipment
DTE, short for Data Terminal Equipment is a device that controls data flowing to or from a computer. The term is most often used in reference to serial communications defined by the RS-232C standard. This standard defines the two ends of the communications channel as being a DTE, and a DCE device.
DCE – Data Circuit-Terminating Equipment
In practical terms, the DCE, or Data Circuit-Terminating Equipment, is usually a modem and the data terminal equipment is the computer itself, or more precisely, the computer’s UART chip.
Comtrol serial ports are Data Terminal Equipment devices except for products which have been specifically designed to be switchable from Data Terminal Equipment to Data Circuit-Terminating Equipment.
When connecting a Data Terminal Equipment device to another Data Terminal Equipment device it is necessary to use a Null Modem cable.
When connecting a Data Terminal Equipment device to a Data Circuit-Terminating Equipment device it is necessary to use a Straight Thru cable.