Intellisystem IT-7304-PC, User Manual, Page: 9 / 12

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5.2 Standard V.35 crossover cable connection diagram
V.35 feet V.35 feet
CGND A
—————
A CGND
GND B
—————
B GND
RTS C
—————
D CTS
CTS D
—————
C RTS
DSR E
—————
H DTR
DTR H
—————
E DSR
TXDA P
—————
R RXDA
TXDB S
—————
T RXDB
RXDA R
—————
P TXDA
RXDB T
—————
S TXDB
EXCA U
—————
V RXCA
EXCB W
—————
X RXCB
RXCA V
—————
U EXCA
RXCB X
—————
W EXCB
5.3 Sittings of switch and jumper
Independent device has totally 5 setting switches, with S5 located on the rear panel and
S1~S4 under the bottom cover. The user can easily make settings without the need to open the
cover.
5.3.1 Clock setting
V.35 interface timing (S5.1= OFF, S5.2=OFF): the sending timing is V.35 port timing, and the
received data, after buffering, is synchronized with V.35 port timing.
Optic interface receiving timing (optic interface originated from the clock, S5.1=OFF
，
S5.2=ON): the sending timing is optic interface receiving timing, and the received data, after
buffering, is synchronized with optic interface receiving timing. Under this timing mode, local
time slot setting can automatically track the opposite time slot setting.
Local main timing (S5.1=ON, S5.2=ON): the sending timing is of local crystal OSC, and the
received data, after buffering, is synchronized with local timing.
5.3.2 Phase selection
S5.4 is used for the receiving phase selection of V.35 interface.
5.3.3 Settings of loopback test and pseudo-random code test
S5.5
～
S5.8 of coded switch S5 are used for setting the loopback test and pseudo-random code
test.
S5.5 is local loopback control
（
LLOOP
）
and optic interface is directly looped back to
V.35 interface. “OFF” indicates normal operation; “ON” indicates local loopback test. The
default is “OFF”. It is used for testing whether local device is in normal operation.