CANOGA PERKINS 2240 Fiber Optic Modem - Manual (Page 16)

Chapter 1 Introduction 2240 Fiber Optic Modem User Manual
2202 Modem Shelf
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Figure 1-2 2201 Rack Chassis
1.3 2202 Modem Shelf
The Model 2202 Modem Shelf is designed to accommodate either one or two standalone 2200
series modems. Hardware is provided for securing the modems side by side in the shelf. The
2202 is designed to fit easily into a 19-inch equipment rack, either flush mount or recess mount.
Figure 1-3 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, Chapter 4, "Data Interfaces". Figure 1-
4 provides a functional block diagram of a the 2240 Modem.