CANOGA PERKINS 2240 Fiber Optic Modem - Manual (Page 49)

Chapter 4 Data Interfaces
RS-530 Interface Model 430
49
local control. In this mode, CTS (Clear To Send) follows RTS locally but is delayed approximately
1 millisecond when RTS turns ON (refer to section 4.4.6). Changing the CTS_OUT jumper
enables the second DTR to CTS control channel. In addition, the CTS (A) jumper allows
configuring the CTS(A) output lead for cryptography applications (refer to section 4.4.8).
4.4.1 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
4.4.2 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, the
DCD output will turn ON either when the modem’s fiber optic receiver is in sync (main board
internal switch S1 CD/DCD = OFF and CD/SYNC = ON) or when the far end RTS is ON (main
board switch S1 CD/DCD = ON and CD/SYNC = OFF).
Factory setting: CTRL
4.4.3 DSR Jumper
The DSR jumper controls the behavior of the DSR signal. The EIA position turns DSR OFF when
the far end 2240 has a local loopback active. The TEST position causes DSR to turn OFF
whenever any loopback is active at one or both of the modems.
Factory setting: TEST
4.4.4 CHASSIS_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 only puts 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
4.4.5 SCT Switch
This slide switch selects whether the SCT leads are outputs (OUT position) or inputs (IN
position). The OUT position makes the 2240 "pure-DCE" and RD data is shifted out in sync with
the 2240-supplied SCR clock. The IN position makes the SCT leads inputs and the 2240 will shift
RD out in sync with the customer-supplied clock on the SCT leads if the main board XTCLK
(W26) jumper is ON.
Factory setting: OUT