Ch_Gnd Jumper; Unbal_Ref Jumper; Rs-423 / Db-25 Interface - Canoga Perkins 2240 User Manual

Canoga Perkins

4.6.1.1.4 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

4.6.1.1.5 UNBAL_REF Jumper

RS-449 specifies that unbalanced inputs to a DCE are to be referenced to the SC (Send Com-
mon) pin. This pin on the DCE is tied to the signal ground of the DTE through the interface
cable. If this ground connection is present, and you prefer to use it, move the UNBAL_REF
jumpers to SC.
Factory Setting = GND

4.6.1.2 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 asyn-
chronous RS-232D systems.
This interface uses the physical connector type and pinouts specified in RS-232D (refer to
Table 4-I). The RS-423/232D interface uses a 25-pin, female D-type connector for the
physical connection.
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