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24
GOOD LABORATORY PRACTICE (GLP)
GLP is a set of functions that allows the storage or retrieval (when
necessary) of data regarding the maintenance and status of the
electrode. The pH electrodes have a built-in EEPROM in which
calibration data are read at start-up and stored after calibration.
HI98230
and
HI98240
can automatically analyze the data and
advise the user if a problem is found with a clear message.
PROBE LIFE VERIFICATION
At the end of calibration, the meter checks if offset is between -30 and
+30mV and the slope between 53.5 and 62 mV/pH. If the values are
not within these parameters, the message "old probe" scrolls across the
LCD and the symbol ** is reported in the Last Calibration Data. The
electrode is still working, but it will be necessary to perform a cleaning
procedure (see electrode cleaning and maintenance paragraph) or
replace it.
If the offset is outside the -60 and +60 mV range, the "dead probe"
message will scroll across the LCD and the symbol -- is reported in
the Last Calibration Data. The readings will blink to warn the user
that they are not reliable.
LAST CALIBRATION DATA
Last calibration data are stored automatically after a successful
calibration. Data can be displayed or printed through the appropri-
ate setup codes (10 to display pH data; 11 to display mV data; 12
to print pH and mV data); mV data are available in
HI98240
only.
ELECTRODE IDENTIFICATION
At start-up the meter checks if the electrode is inserted. If not the
message "no probe" scrolls across the LCD and a dashed line will be
display in place of the reading. Each printout will have a "
◊
" symbol
on the pH line.
If the meter detects a "dead probe" the reading will blink.
The meter checks the electrode only at start up. If an electrode
replacement is needed, turn the meter off before disconnecting the
electrode. Then replace the electrode and turn the meter on again.
CALIBRATION ALARM TIME-OUT
The calibration alarm time-out is available only for pH calibration.
It is possible to set (through setup code 13) the number of days
before the next required calibration procedure. User can set a value
from 00 (disabled) to 99 days. The default value is 00.
"Stor log" and the value will be stored in the lot 00 (log on demand
data area). If the printing function is enabled, a printout is also
produced providing the following information:
a - Date
b - Sample number
c - Time
d - Readings
Note:
When the Log on demand data area is full and the LOG key
is pressed, the sample will not be stored and the LCD will
display "FULL". In this case it is necessary to delete the Log on
demand data to proceed.
TO RETRIEVE LOGGED DATA
Logged data stored in the EEPROM can be viewed on LCD or printed.
HI98230
and
HI98240
also allow the downloading of logged data to
PC for reproduction, storage and elaboration (e.g. graph drawing).
To view or print logged data see "TO SCAN LOGGED DATA" on page 11.
To download data to PC see "DATA TRANSFER TO PC" on page 27.
OTHER FEATURES
LCD BACKLIGHT
The LCD can be illuminated to allow the user to see the readings even
in dark environments. This feature can be enabled/disabled pressing
the ALT and LIGHT keys.
If the LCD backlight feature is enabled, the LCD remains illuminated
until the feature is disabled pressing the ALT and LIGHT keys. The
LCD backlight can be disabled in order to save power and it is
automatically disabled when batteries are in low battery condition.
Note:
When an external power supply is connected to the instru-
ment, the backlight is not automatically enabled.
Note:
When LOBAT appears on LCD it is not possible to enable
backlight. If the user attempts to enable the LCD backlight in
low battery condition, the meter will show "bAtt" on LCD.
Real Time Clock (RTC)
The instrument has an internal Real Time Clock (RTC) circuit with a
backup lithium battery. This allows the meter to update time and
date even when both batteries and external power adapter are
disconnected.
