CANOGA PERKINS 2240 Fiber Optic Modem - Manual (Page 44)

2240 Fiber Optic Modem User Manual Chapter 4 Data Interfaces
RS-449/422 Model 422
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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
4.2.2 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
4.2.3 DSR Jumper
The DSR jumper controls the behavior of the DSR signal. The EIA position causes the DSR to
turn OFF in certain test conditions when the transmit data is blocked and has no end-to-end or
loopback path. This condition exists when the far-end 2240 modem has a local loopback active.
The TEST position causes DSR to turn OFF (negate) whenever any loopback is active at one or
both modems.
Factory setting: EIA
4.2.4 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
4.3 RS-449/422 Model 422
This interface complies with EIA Standard RS-449. Electrical characteristics comply with RS-422
for clock and data signals and RS-423 for control signals.
The RS-449/422 interface applies the physical connector type and pinouts specified in RS-449
(refer to Table 4-3). The interface uses a 37-pin, female D-type connector for the physical
connection.