Casella CEL CEL-281 User Manual
Page 44
The microprocessor also controls the storage and transmission of calcu-
lated and measured data. The 32 kbyte EPROM contains computing and
control programs, while the 32 kbyte non-volatile RAM allows up to 14
hours of noise data to be stored.
A real time clock controls all time and date functions with an accuracy
better than 5 seconds in 24 hours. When the
key is pressed to
start the collection of data, logging will always start as the clock passes
the next full minute of time, but will stop logging immediately the
+
key combination is pressed.
Both clock and RAM are also powered by an additional back-up battery,
so that neither time information nor memory contents are lost if the
main batteries are exhausted and have to be changed. The back-up bat-
tery has a usable life in excess of two years, after which it must be re-
placed. Please consult CEL Service Department for details. The main
power supply for the instrument consists of a set of four type AAA bat-
teries contained in a slide-in battery holder. The operating life of the
main battery supply is greater than 16 hours.
Operator commands and data for transmission are carried over the 15-
line connector which constitutes a CEL low-power interface bus. The
bus allows direct connection to a CEL-6012 Keypad, and connection via
a C6228/2 (2 m) Cable to a PC so that the measurement conditions can
be set and data transferred.
3.3
Control Facilities: CEL-6012 Keypad
This handbook describes operation of the CEL-281 Dosimeter only with
the CEL-6012 Keypad. Operation with a PC is described elsewhere. The
commands required to set measurement conditions and display particu-
lar parameters are initiated by pressing the keys on the keypad, shown
in Figure 8.
How It Works
Page 36 - CEL-281 Operator's Handbook