Comtech EF Data SMS-458B - Manual (Page 20)

SMS-458B Modem Protection Switch Revision 2
Introduction MN/SMS458B.IOM
1–4
1.3 Description
The switch is complete and self-contained in a standard 19-inch (48 cm) rack-mounted
enclosure weighing approximately 50 lbs (22.68 kg). Modular construction methods were
used for ease in replacing modules.
The chassis assembly is segmented with upper and lower chassis-mounted backplanes.
The top section (Figure 1-3) contains:
• Two power supplies and four printed circuit board (PCB) assemblies, providing:
! Front panel keypad and display accessible from the front panel.
! Serial remote interfaces, relay-remote/fault, status, and IF connections
accessible from the rear panel. Refer to Figure 1-4 for a block diagram of the
IF switching matrix.
The lower section (Figure 1-5) contains:
• High-speed data switching matrix and matrix driver.
• Data switch interface modules accessible from the rear.
Refer to Figure 1-6 for the interconnect diagram of the lower section.
The switch contains a microcontroller system. This system controls all switching
functions and maintains communication with the modems. It also communicates with an
optional external controller. A remote operator can control the switching by using a
terminal or computer and the remote serial interface.
Redundant power supplies maintain switch operation even if one power supply fails. The
switch and modem configurations are stored in battery-backed memory devices for
protection against power loss.