UniData Communication Systems Starlog Prologger 7001, User Manual

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2.2 How the PROLOGGER Operates
The PROLOGGER must be “initialised” before it can be used. This is done
automatically when you load a scheme. Alternatively, you can manually
initialise the device (see
PROLOGGER Initialisation
on page 30). Note that
when delivered, the PROLOGGER is shutdown to conserve batteries. It must
be initialised before use.
The PROLOGGER switches on once per scan. You must specify the scan
rate. It performs three operations each time it is switched on: scanning,
inter-log analysis, and RS-232 comms check. It then switches off. This
sequence occurs every scan interval. It performs a fourth operation, logging,
at an interval you specify. These operations are described below.
n
Scanning
Scan rates, which can be from 125 milliseconds to 5 minutes, determine how
frequently the logger switches on. When it switches on, the logger scans its
input signals. These signals, called the
hardware values
, are recorded in the
PROLOGGER memory. The hardware values are updated in the logger
memory every scan.
n
Interlog Analysis
After scanning the input signals the logger program performs an
inter-log
analysis of the hardware values, storing the analysed values in a different part
of the logger’s memory referred to as the
Register
. The inter-log analysis
includes: averaging and storing maximum, minimum and raw values. For
example, if a certain channel is programmed to store maximum values of its
input, the logger will check to see if the hardware value is higher than the
value already stored in the Register. If so, it will update the Register. If not,
then it changes nothing and goes to the next instruction. The Register is used
to store data between log intervals.
n
RS232 Comms
When the scan occurs at a log interval, the logger program records data found
in the Register into another part of its memory. Here, the data remains until
the logger is unloaded (or until the entire memory storage space is filled, then
earlier stored data may be overwritten when recent data is logged).
PROLOGGER Hardware
PROLOGGER OVERVIEW 5