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DTE Loop Control
The local loop and remote loop can be activated from the DTE
interface using signals “LL” and “RL”.
SW2-4
On Enable LL and RL inputs
Off Disable
Clock Mode
The appropriate transmitter clocking modes can be selected for
Dedicated DDS, Switched-56 or campus-area (private) operation.
SW2-5 SW2-6 Mode Description
On Off External Clock Mode Transmit Clock derived
from terminal interface
Off Off Network Clock Mode Transmit clock derived
(Looped Clock Mode) from the received line
signal; Use this mode
for Dedicated DDS
operation
On On Internal Clock Mode Transmit Clock derived
internally
Off On Switched 56 (Model 2510, 2520)
Anti-Stream Timer
The anti-stream timer protects multidrop networks from a drop that
is continuously transmitting. If the terminal keeps RTS raised for more
than 30 seconds, the timer forces RTS off internally. This allows the
rest of the multidrop network to resume operation. The CSU/DSU
remains in the forced-off condition until the terminal drops RTS.
Timer Value in Sec at Various Line Rates
SW2-7 Timer 56 19.2 9.6 4.8 2.4
On Disabled
Off Enabled 2 4 8 15 30
CTS Delay
The RTS/CTS turn-on delay can be set to Normal or Extended.
Delay in mSec at Various Line Rates
SW2-8 CTS Delay 56 19.2 9.6 4.8 2.4
Off Normal 0.3 0.9 1.9 3.8 7.5
On Extended 1.3 3.8 7.5 15 30
4.2 CONFIGURATION USING SOFTWARE SWITCHES
The Model 2500 Series CSU/DSUs can be soft configured using a
VT100 terminal or similar RS-232 DTE with terminal emulation. To use
software switches for configuration, follow these steps:
1) Connect the serial RS-232C port of the terminal to the modular
EIA-561 control port on the front panel of the Model 2500 Series.
To construct an RS-232 to EIA-561 patch cable, refer to the control
port pinout diagram in Appendix D.
2) Power up the terminal and set its RS-232C port as follows:
9600 baud
8 data bits, 1 stop bit, no parity
local echo
CR = CR/LF on inbound data
ANSI, VT-100 emulation
3) Key menu, then press [RETURN]. The Model 2500 Series
Main Menu should then display on the terminal screen (see below).
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