Switches S1-1 and S1-2: Clock Mode
The setting for switches S1-1 and S1-2 determines the transmitter
clocking mode for the Model 2400.
S1-1
S1-2
Clock Mode
Description
On
Off
External (DTE)
Transmit clock derived
from terminal interface
Off
On
Network (Looped)
Transmit clock derived
from the received line
signal; Use this mode
for Dedicated DDS
operation
Off
Off
Internal (Master)
Transmit clock derived
internally
On
On
Campus Clock
Transmit clock derived
from received line signal.
Allows remote device (in
campus clock mode) to
initiate V.54 loopback. For
use only in campus short-
haul configuration (Note:
Opposite device must be
in internal clock mode).
6
3.1 CONFIGURATION SWITCH SET ‘S1’
The Model 2400 uses a set of eight internal switches to set
clocking mode, circuit assurance, RTS control, data rate and loop
control. Figures 3 (Model 2400/A) and 4 (Model 2400/C) show the
switch and jumper locations with respect to the other components on
bottom side the PC board.
Figure 5 (below) shows a close-up of DIP Switch S1 with respect to
ON and OFF positions. Default switch settings are shown in the table
on the following page. Descriptions of each switch follow the table.
5
SWITCH SET 1 SUMMARY TABLE
Position
Function
Factory Default
S1-1
Clock Mode
Off
S1-2
Clock Mode
On
S1-3
Circuit Assurance
Off
Disabled
S1-4
RTS
On
Forced On
S1-5
Data Rate
Off
56 Kbps
S1-6
Front Panel Switch
Off Enable Front Panel
Control
Switches
S1-7
DTE Loop Control
On
Loop Control
From DTE Disabled
S1-8
Receive RDL
Off
Receive RDL
Enabled
Network
}
Figure 5. Close-up of DIP Switches Showing “ON” and “OFF” Positions
1
2
3
4
5
6
7
8
ON
OFF
ON
ON
1 2 3 4 5 6 7 8
ON
12345678
Figure 3. Position of the DIP Switches on the 2400/A PC board
Figure 4. Position of the DIP Switches on the Model 2400/CM PC board
Switch S1
Switch S1
