CANOGA PERKINS 2240 Fiber Optic Modem - Manual (Page 62)

Chapter 4 Data Interfaces 2240 Fiber Optic Modem User Manual
Multi-Channel Interfaces
62
4.6.11 RTS_BIAS Jumper
The RTS_BIAS jumper controls the state that RTS floats to when there is no signal driving the
RTS pin. The OFF position forces this signal to the OFF (negated) state when the interface cable
is disconnected. The ON position forces it to ON (asserted).
Factory setting: OFF
4.6.12 DCD Jumper
The DCD jumper determines the source of the DCD output. In the CTRL position, the DCD
output functions as the output for the RTS input at the far end. In the CD jumper position and with
local RTS ON, CTS will turn ON either when the modem’s fiber optic receiver is in sync (main
PCBA internal switch S1 CD/DCD = OFF and CD/SYNC = ON) or the state of the RTS signal at
the far end (main PCBA internal switch S1 CD/DCD = ON and CD/SYNC = OFF). Refer to
section 2.1.3.1 for more information on the internal switch S1 CD/DCD and CD/SYNC positions.
Factory setting: CTRL
4.6.13 CTS_GATE Jumper
The CTS_GATE jumper controls the state of CTS when the local RTS is ON. When the jumper is
in the ON position, CTS follows RTS only. The CD position allows the 2240's standard data
interface signal CD to gate CTS. In the CD jumper position and with local RTS ON, CTS will turn
ON either when the modem’s fiber optic receiver is in sync (main PCBA internal switch S1 CD/
DCD = OFF and CD/SYNC = ON) or the RTS signal at the far end is ON (main PCBA internal
switch S1 CD/DCD = ON and CD/SYNC = OFF). Refer to section 2.1.3.1 for more information on
the internal switch S1 CD/DCD and CD/SYNC positions.
Factory setting: ON
4.6.14 CH_GND Jumper
The jumper selects whether chassis ground is connected directly to signal ground (SHORT
position) or through a 100 Ohm resistor (100_OHM position).
NOTE: In the standalone model, the 100_OHM position will only put a 100 Ohm
resistor between the two grounds if the 2240's main board SIGNAL GND
jumper is set to the FLOAT position. When installed in the 2201 Rack
Chassis, any modem main board, interface or rack chassis jumper being
set to SHORT will override the FLOAT and 100_OHM positions on all of
the other modems. CONSIDER THIS JUMPER CAREFULLY.
Factory setting: 100_OHM
4.6.15 RS-423/DB-25 Interface
NOTE: The maximum data rate for this interface is 9.6 Kbps.
This interface is electrically compatible with EIA RS-423A. It will also operate with asynchronous
RS-232D systems.
This interface uses the physical connector type and pinouts specified in RS-232D (refer to
Table 4-10). The RS-423/232D interface uses a 25-pin, female D-type connector for the physical