Dte Vs. Dce - National Instruments AT-232/2 Getting Started

Appendix B Serial Port Information

DTE vs. DCE

Serial for Windows NT
Figure B-4 shows a transmission line using bias resistors.
A
B
Figure B-4. Transmission Line Using Bias Resistors
Rather than using two 620 Ω resistors at one node, you can also increase
the value of the resistors and put them at every node. For instance, if
there are eight nodes in a system, you can use 4.7 kΩ resistors at each
node to effectively achieve the same result.
Data Terminal Equipment (DTE) and Data Communications Equipment
(DCE) were the terms used in the RS-232 specification for the types of
equipment on either end of a serial connection. (A DCE is called Data
Circuit-Terminating Equipment in Revision D of the RS-232
specification.) In general, DTE and DCE refer to computer equipment
and modems, respectively. Because the RS-232 specification mainly
involves connecting a DTE directly to a DCE and vice versa, the pinouts
are defined so that cabling is simple. That is, a cable connected a
computer to a modem by wiring pin 1 to pin 1, pin 2 to pin 2, and so on.
This method is commonly known as straight-through cabling.
+5
Tx
B-6
620 Ω
Bias Resistor
100 Ω
Termination Resistor
620 Ω
Bias Resistor
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