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DIDCSU E1 Version
Table 4-7
Data Port Configuration Menu Parameters
Command
In
In Service: Use this option to place the port in service.
Mn
Data Port Mode: Use this option to select one of the following:
• Data Terminal Equipment (DTE): if the equipment connected to the
DIDCSU is a DCE, then the Data Port Mode is DTE. Mostly used with tail
circuits. However, using a crossover cable is a better option. See the
manual AS 2000: The Basics.
• Data Circuit-terminating Equipment (DCE): if the equipment connected
to the DIDCSU is a DTE, then the Data Port Mode is DCE. DCE is the
default setting and is by far the most commonly used.
Cn
Clock Option: Use this option to select one of the following:
• Serial Transmit (ST): In this mode, the DIDCSU data port samples the
Transmit Data lead during the negative-going transition of the
Transmit Clock signal provided by the DIDCSU. This is the default
setting.
• Inverted Serial Transmit (INV ST): In this mode, the DIDCSU data port
samples the Transmit Data lead during the positive-going transition of
the Transmit Clock signal provided by the DIDCSU. This is useful when
compensating for phase delays (caused by using long cables) and
when the far end is receiving bit errors reported by a higher level
protocol-but not the far CSU/DSU.
• Terminal Timing (TT): In this mode, the optional third pair of clock
leads (Serial Clock Transmit Extension—SCTE in V.35, Terminal
Timing—TT in RS-422) is used to clock data from the DTE into the
DIDCSU module's data port transmit buffer. Normally, this clock is
looped by the DTE from the Transmit Clock signal. It is the preferred
timing method because the transmit clock and data are always in sync
regardless of cable length. Unfortunately, this signal is not provided by
all DTE equipment. Select this option in tail-circuit-timing applications
(when the data port receives timing from another circuit).
On
Enable Loss-of-Signal (LOS) Detection: Indicates if the cable is plugged
into the data port. If set to DTR, an alarm is generated if the cable is
unplugged, or if the DTE equipment drops the handshake lead. In DTE
port mode, this is a DSR lead.
Ln
Control Lead Mode: If Control Lead Mode is AUTO then CTS(Clear To
Send) is returned when the DTE presents RTS(Request To Send) and
DSR(Data Set Ready) is returned when the DTE asserts DTR(Data Terminal
Ready).
If Control Lead Mode is set to MANUAL then every control lead is
immediately forced off until it is explicitly forced on (Using SRn, and
SSn).
SRn
Data Set Ready (DSR): This is a DCE output. LOW indicates the lead is off
(negative voltage). HIGH indicates DSR is on.
In Control Lead Mode AUTO DSR is on when the DTE asserts DTR. If
Control Lead Mode is set to MANUAL then DSR is immediately forced off
until the user explicitly forces it on.
Data Terminal Ready: This is a DTE control lead. LOW indicates the lead
is always off (negative voltage). HIGH indicates the lead is always on.
4-14
Description
Verilink DIDCSU 2912 User Manual
Options
Yes or No
(Y/N)
1) DTE
2) DCE
1) ST
2) INV ST
3) TT
1) NO
2) DTR
1) LOW
2) HIGH
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