P521/EN AD/B21 Update Documentation
Page 20/24 MiCOM P521
MODEM CONFIGURATION (P521/EN MC/B11)
2. Definitions
Unconditioned pilot
wires:
Twisted pair of metallic wire between 19 (0.9mm) and
26AWG (0.4mm). Standard dial-up telephone circuits,
leased circuits that run through signal equalisation
equipment or standard flat modular telephone cable are not
acceptable.
Conditioned leased
lines:
Leased circuits that run through signal equalisation
equipment using the standard flat modular telephone cable.
Modem: Generic name for a converter of digital data to a format
suitable for transmission over unconditioned pilot wires or
conditioned leased lines.
Baud: The number of data symbols transmitted every second.
DCE: Data Communication Equipment i.e. modems, protocol
converters and line drivers.
DTE: Data Terminal Equipment i.e. PCs, terminals and protection
relays.
Handshaking: Confirmation and status signals sent between
communicating devices in order to check the data stream.
There are two general types, hardware (RTS/CTS) and
software (XON/XOFF).
TD: Transmitted data. Data going from DTE to DCE.
RD: Received data. Data going from DCE to DTE.
RTS: Ready To Send. Hardware handshake generated by the DTE
to determine if the DCE is ready to receive data. Expected
response is from the CTS line.
CTS: Clear To Send. Hardware handshake generated by the DCE
in response to a RTS signal.
DSR: Data Set Ready. A signal from the DCE used to indicate that
it is powered and useable.
DTR: Data Terminal Ready. A signal from the DTE showing it is
powered and ready.
DCD: Data Carrier Detect. A signal from the DCE showing that a
carrier is present and the line is ready for data transmission.
1
ON
Switch shown in ON position.
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