Service manual CS3000
Chapter 3: Alarm processor board LPK-2 3-12
The circuit boards of the central unit
Document no.:
S-4-007.875/E
Prepared:
1995-03-17 Fia
Revision:
R4 2004-03-15 BM
© 2002, Consilium Marine AB
1. DC/DC converter
The DC/DC circuit converts the battery voltage of the back plane to 5 VDC,
which is supplied to all logical circuits on the board.
2. CPU/Memory/Watchdog
This is the main block of the LPK-board. The CPU uses the memory circuits for
executing the programme code. There is also a non-erasable memory containing
the system configuration and the external controls. The watchdog supervises the
processor and checks that there are no hang-ups in the programme execution.
3. LED indications
One green LED indicates that the board is power supplied. If the watchdog is
activated (possible fault in the board), a yellow LED is lit, indicating system
fault. Furthermore there are two LEDs (one yellow and one red) indicating fault
and alarm in the central unit. Finally there are two green LEDs that are used for
service purposes.
4. Address switch
With the DIP switch the 8-bit address of the LPK is set.
5. Real time clock
The real time clock is keeping track of the time in the system. The clock has
built-in registers for seconds, minutes, hours, days, week-day, month and year
(including leap-years). The real time clock is reset from the control panel.
6. Internal communication loop (RS485)
The internal communication loop is connected to all SPKs in the same rack
system. All SPKs are polled and supervised via this loop.
7. Loop switch
The loop switch changes the communication channel from one external loop to
the other.
8. System communication loop (RS422)
This block contains the communication with control units and other central
units.
9. Data/address buffers
All bus connections going from the back plane are buffered in special buffer
circuits.
10. Back plane signals
Certain hardware signals in the back plane are read by the LPK after a voltage
conversion.
11. Basic-alarm
The basic-alarm function is activated if a SPK or the LPK is faulty and therefore
incapable of transmitting an alarm. This board will block the basic-alarm
function if the processor is in proper working order.
12. Fire brigade output
Two relay outputs for connection to the fire brigade. The alarm relay is
programmable and the other relay is activated when there are not muted faults in
the system.
