8
IM620-1
Figure 2. Microprocessor Control Board (MCB)
RUNNING
RESET
ACTIVE
OUTPUT 0
CPU
STATUS
POWER FUSES
[BUSSMAN GDC-T2A]
POWER IN
[18-24 VCT]
AC AC GND GND
AUX
/
OUT
DIGITAL OUTPUTS
ANALOG INPUTS
DIGITAL INPUTS
HI
ADDRESS
LO
KEYPAD
/
LCD DISPLAY
COMMUNICATIONS
PORT A
PORT B
[FUSE: BUSSMAN MCR-1/4]
FUSE 1
2
3
4
Hex switches
Microprocessor status LED's
EXPANSION BUS
Digital Outputs Connection
After processing all input conditions and network data, the MCB sends the appropriate output
signals to output devices through the Digital Outputs port via a plug-in ribbon cable.
Aux/Out Terminal Strip
The Aux/Out terminal strip provides 5 Vdc and 13 Vdc to the MAG field wiring terminal strip. The 5
Vdc is used to power auxiliary equipment. The 13 Vdc can be used to power an Analog Output
Expansion Module (see the “Accessories” section of this manual for more information on the Analog
Output Expansion Module).
Power In Connector
The MCB receives 18 Vac, center-tapped power through transformer T2 and the Power In connector.
This power drives all logic and communications circuitry, and the Aux/Out terminal strip. Refer to the
panel’s wiring diagram or Figure 15 for more information.
Power Fuses
Two identical 2-amp fuses are located to the right of the Power In terminal strip. These fuses are in the
MCB power supply circuit.
Microprocessor Status LEDs
The green, red, and amber LEDs on the MCB provide information about the operating status of the
microprocessor. The amber LED also indicates the existence of alarm conditions.
Following is the normal start-up sequence that the three status LEDs should follow when power is
applied to the MCB:
1.
The red (“Reset”) LED turns on and remains on for approximately 5 seconds. During this period
the MCB performs a self-test.
2.
The red LED turns off and the green (“Running”) LED turns on. This indicates that the
microprocessor has passed the self-test and is functioning properly.
