DT Etherlink IV
User Manual
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CONTRA (contradirectional): Transmit clock and transmit data have opposite directions, i.e.
transmit clock is an output from the modem at signal number 114 and transmit data is an input
to the modem at signal number 103.
In combination with the command SETCLOCK (units with Nx64 interface have the possibility to set
the clock source to the SHDSL line side as Nx64 clock (parameter “V35” of SETCLOCK
command)), it is possible to realise different clock schemes. The following table shows different
valid combinations of clock modes for the Master modem:
Command:
EXTCLOCK
SETCLOCK
Argument:
SRC
DIR
Modes:
DTE
Clock Mode
DCE
Clock Mode
DCE
Clock Direction
xDSL
Clock Mode
D
S
L
p
ay
loa
d
Nx64 only,
Nx64 * & WAN
Slave
internal
don’t care
internal
Master
external
codirectional
Nx64
E1 & Nx64
E1 & Nx64 & WAN
Slave
DSL
don’t care
E1
The following table shows different valid combinations of clock modes for Slave modem:
Command:
EXTCLOCK
SETCLOCK
Argument:
SRC
DIR
Modes:
DTE
Clock Mode
DCE
Clock Mode
DCE
Clock Direction
xDSL
Clock Mode
D
S
L
p
ay
loa
d
Nx64 only,
Nx64 * & WAN
Slave
DSL
don’t care
Nx64
E1 & Nx64
E1 & Nx64 & WAN
Slave
DSL
don’t care
E1
Interface V35-1:V35
Extrate : 128
Autoloop : ON
Extclock : TTC/CO
Interface V35-1:V35
Extrate : 128
Autoloop : OFF
Extclock : NORMAL/CONTRA
Figure 3.13. Application Example V.35 with external clock master
104
115
113
103
105
108
106
107
109
codirectional
contradirectional
103
114
115
104
105
108
106
107
109
DTE
SHDSL MODEM
Nx64
Nx64
DCE
DCE
Clock External
Clock Remote
MASTER
SLAVE
SHDSL MODEM
DTE
