2200R Series Redundant Card; Modem Operation; General; Model 2202 Modem Shelf - Canoga Perkins 2240 User Manual

Canoga Perkins
Figure 1-3.
Model 2202
Modem Shelf

1.4 2200R Series Redundant Card

This card allows a single electrical interface to be shared between two modems
installed in a 2201 Rack Chassis. This model can be operated in three modes:
Remote control, Manual control and Automatic. In the Remote control mode, two
contact closure inputs (which are also RS-232 level compatible) are provided to
permit forcing the modem to receive on either the primary or secondary link.
Transmission occurs only over the selected link.
Two 2240s can operate as a single redundant pair when operating in a 2201 Rack
Chassis. The 2200R board is the redundancy controller and signal switch. The
combination of these three boards (two rack-mount modem cards and a 2200R card)
occupy three slots to provide a redundant fiber optic path. Special interface boards,
Redundant Paddle Boards (4PB) are substituted for the normal I/O boards in the two
modems. Refer to the 2201 Rack Chassis / 2200R Redundant Modem Card User
Manual.

1.5 Modem Operation

1.5.1 General

The 2240 Modem can use an external clock, provide the master clock, or one end
can be slaved to the other for either of these cases. The electrical connection
between the data equipment and the 2240 Modem differs from model to model
depending on which interface is employed (modem is usually DCE). The electronic
conversion from voltage level to optical signal level is similar in all applications. For
a description of the available interfaces, refer to Section 4. Figure 1-4 provides a
functional block diagram of a the 2240 Modem.
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