June
1998, Issue 95
Gotchya!
Alarming
the Alarm System
by
Steve Ciarcia & Jeff Bachiochi
Getting
Goods
Displaying
and dumping the stored data log is a secondary function
chosen from the command menu. The ASDL LCD can show
a command list, the time and date, or the data. The
data is printed to the LCD in blocks.
When
the log is dumped, all the blocks up to and including
the present time and date are dumped. We didn’t
see the necessity for individual date interrogation.
You
want the data log? Here’s everything, a block at
a time.
While
the data is being sent to the LCD, it is also sent out
the console serial port. Although this could be connected
to a PC and logged to a file, Jeff mounted a plain-paper
12-VDC–powered serial printer (measures only 5²
´ 5² ´ 3²) next to the Domino, so a hardcopy of the
data could be printed and retained if necessary.
A
short pause between each block lets the printer keep
up with the data and provides time to study each block
on the LCD before the next display. The final menu selections
enable the user to clear all data from the data buffer
and return from the menu screen to the idle screen (displaying
time/date).
Since
the capturing and logging of alarm codes is a security
risk, it would be foolish not to try to prevent unauthorized
use. Accessing the menu screen shouldn’t be open
to just anyone.
Any
ASDL entry prompts the user for a PIN. An incorrect
entry simply returns to the idle screen.
We
also specifically chose to store the data log in SRAM
rather than EEPROM. If the Domino is removed from the
system, the data log disappears.
