Specifications

Appendix C - Glossary of Terms RS-422 And RS-485 Applications Ebook
Page 110 of 137 Manual Documentation Number: <DocNumber>
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A conductive wrist strap and grounding cord used to discharge static
voltages to ground when handling ESD (Electro Static Discharge) sensitive
devices such as interface cards.
H
Half Duplex
In a half duplex communications system a device can either receive or
transmit, but not both at the same time. Many radio transmission systems are
half duplex because the transmitter and receiver use the same frequency, and
while transmitting mute the receiver. A RS-485 two-wire system is also half
duplex because it uses the same pair of wires to transmit and receive.
Handshake Lines
In an RS-232 serial system, data flow control is performed using the CTS
(Clear To Send) and RTS (Request To Send) control lines. The DSR (Data Set
Ready) and DTR (Data Terminal) control lines are used to determine if a device
is connected and active. Additional lines for DCD/CD (Carrier Detector) and RI
(Ring Indicator) are used with modems.
Handshaking
The process of using handshaking lines or software data flow control such as
X-On/X-Off to transfer each byte of data.
Hardware Flow Control
Serial Port transfer using the RTS and CTS control lines to control data flow
instead of using software flow control using X-On/X-Off control with a full
duplex serial link.
Parallel data transfer in which handshaking for each data byte is handled
automatically by the hardware rather than by computer instructions that
alter each of the 4 hardware states