Comtech EF Data SMS-458B - Manual (Page 79)

SMS-458B Modem Protection Switch Revision 2
Theory of Operation MN/SMS458B.IOM
4–19
4.4 IF Switch Driver
The IF switch driver (Figure 4-6) is a 10.5 x 3.5 inches module that fits into slot 3 of the
upper-front section of the switch chassis. It controls activation of the baseball switches on
the IF Switch card.
Both +5V and +12V are utilized on this card.
The M&C uses the address decoder/driver with an 8-bit data bus and one device select
line to control the switch driver. The switch driver decodes commands from the M&C
card and activates the appropriate baseball switches on the IF switch in accordance with
these commands.
Refer to Figure 4-7 for a block diagram of the IF Switch Driver card.
IF SWITCH RELAY DRIVER
SMS-758
FSCM 4J515
AS/1316 REV _______
S/N ________________
Figure 4-6. Switch Driver
TO BASEBALL
SWITCH 1
X 22 BASEBALL
L
A
T
C
H
M&C
DATA BUS
FROM M&C
X 8
CARD SEL
INTF
COMMAND
DECODE
X 22
DRIVERS
+12V
TO BASEBALL
SWITCH 22
TO IF SWITCH
Figure 4-7. IF Switch Driver Block Diagram