46023-12-0399 <90-00009>
P
AGE
3
CIRCUIT DESCRIPTION
T
he functional schematic for the 46023-12 Smart Multiple
Alarm Combiner (MAC) is shown in Fig. 1.
♦
The Smart MAC uses a 68008 microprocessor operating at
10 MHz to process data between the eight data ports and the
master port. If the microprocessor malfunctions, a watchdog
timer generates a hardware reset.
♦
The address of the Smart MAC is defined by a selectable DIP
switch setting.
♦
An eight-port Universal Asynchronous Receiver Transmitter
(UART) is used for serial communications with remote alarm
and control equipment. Data is transmitted and received
through RS-422 drivers and receivers. The receive lines have
an optional strap selection for 100-ohm termination. The
configuration of the MAP determines the data rate and proto-
col of each port.
♦
The master port is used for serial communications with the
MAP. It has a single-port UART with a TTL/CMOS interface.
Select the data rate and protocol by DIP switches.
♦
Front panel displays and switches provide several modes for
alarm status reporting and acknowledgment. The firmware
of the MAP determines the functions that are displayed and
controlled.
♦
The regulated power supply uses -21 to -56 VDC input power
to supply ±12VDC and +5VDC to the modules circuit board.
In addition, the output from the power supply is available off-
board through edge connector pins 45 (+5 VDC), pin 47
(+12 VDC), and pin 49 (-12 VDC).