CANOGA PERKINS 2240 Fiber Optic Modem - Manual (Page 48)

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Canoga Perkins
Local Loopback (LL) and Remote Loopback (RL) are loopback control leads and
perform the same functions as the 2240 front panel LOOP switch LOC and REM
positions. LL and RL are interface signal inputs which can be used to activate the
LOC or REM loop functions. These signals can control the loopback functions
only if the front panel switch is in the center OFF position.
4.3.1 RS_BIAS Jumper
The RS_BIAS jumper controls the state that RS floats to when there is no signal
driving the RS 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
4.3.2 RR Jumper
The RR Jumper determines the source of the RR output. In the CTRL position,
the RR output functions as the output for the RS input at the far end. In the CD
jumper position, the RR output 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 far end RTS is ON (main PCBA internal switch S1 CD /
DCD = ON and CD / SYNC = OFF). Refer to Section 2.2.2.1 for more informa-
tion on the internal switch S1 CD / DCD and CD / SYNC positions.
Factory setting = CTRL
4.3.3 CS_GATE Jumper
The CS_GATE jumper controls the state of CS when the local RS is ON. When
the jumper is in the ON position, CTS follows RS only. The CD position allows
the 2240's standard data interface signal CD to gate CS. In the CD jumper
position and with local RS ON, CS 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 2.2.2.1 for more
information on the internal switch S1 CD / DCD and CD / SYNC positions.
Factory Setting = ON