4RF Aprisa XE User Manual page 143

DTE to DCE Mode 3: RxC (X.21) - 40 kbit/s overhead (Pass-through clocking)
DTE clocks DCE clocks
used used
RxC RxC
DTE to DCE Mode 6: RxC
DTE clocks DCE clocks
used used
RxC and RxC and
TxC TxC
Clock passing
40 kbit/s of overhead used to
transport RxC from the DTE to
DCE.
RxC - No overhead (Primary/ Secondary Master clocking)
Clock passing
The DTE XTxC is derived from
the RxC and is used to generate
the terminal external clock.
The DCE generates RxC and TxC
from the terminal clock.
Aprisa XE User Manual
Configuring the Traffic Interfaces | 141
Comment
Preferred option for X.21.
Comment
HSS becomes the External master
clock, avoiding explicit clock
passing, but foregoing the use of
passing a clock in either direction
(Modes 1, 5).
The DTE HSS card must be set as
the External clock for the
terminal.