Specifications

Appendix C - Glossary of Terms RS-422 And RS-485 Applications Ebook
Page 105 of 137 Manual Documentation Number: <DocNumber>
www.bb-elec.com/
www.bb-europe.com/
DB9
9 pin "D" type connector(looks like a sideways D) The top row has 5 pins (or
holes for pins), the bottom has row has 4 pins (or holes for pins). If the
connector has pins, it is a plug (historically called a male connector); if it has
holes to accept pins, it is a receptacle (historically called a female connector).
DCE
Data Communications Equipment. A device is considered a DCE if it facilitates
communications, as opposed to originating the data to be transmitted. It is
important to know whether a piece of equipment is considered a DCE as this
determines the pin-out of its RS-232 ports. When connecting a DTE to a DCE,
a straight-through serial cable must be used. The straight-through cable
connects the DTE's transmitter output to the receiver input on the DCE. When
connecting a DTE to a DTE a null modem cable is required. (Null modem cable
crosses the pins to connect the Tx on the first DTE to the Rx on the second
DTE.
Differential Signaling
Physical signaling method by which a pair of wires is used to transmit a signal.
The differential transmitter (+) and (-) outputs are 180 degrees out of phase
with each other (when one is +5V, the other is 0 volts, and when the first is 0
volts, the second is +5V). The receiver uses the difference between the two
lines to determine the digital state. With differential signals, any induced
common mode signals picked up on the twisted pair wires are canceled at the
receiver since it sees only the difference signals. Differential signals and
common mode rejection help provide reliable serial communication over larger
distances than single ended communications.
DIN Rail
A standard metric sized mounting rail for use in a equipment rack or cabinet.
Product housings/packages designed to attach to standard sized DIN rails.