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5.4 Front Panel Controls – Fig. 5.2
The programme controls comprise eight tactile membrane
switches. These switches are situated behind a hinged door
below the display, access is via a screwdriver-operated catch. In
normal operation the switches are used to view the measured ion
concentration value, initiate a manual calibration, or to activate
the 'alarm hold' facility.
When programming, the switches are used to sequence through
a programming procedure as detailed. The procedure is set out in
programming pages for Input, Current Output, Alarms, Real Time
Clock and Monitor Calibration. Each programme page contains
the programme functions, the values or parameters of which are
programmable.
Switch functions are as follows:
Used for viewing the
electrode mV output, flowcell control temperature,
Mode
electrode slope, date, time, the day of the next
calibration and the date of the last calibration.
Used to enable or disable the automatic calibrations,
enter the standard solution values and manually
Cal
initiate a calibration sequence. Operating 'Cal'
during a calibration aborts the sequence and returns
to normal operation.
Used to inhibit any change in the alarm relay/l.e.d.
status and the start of any auto calibration. The feature
Hold
is used during maintenance ('Hold' l.e.d. illuminated).
✶
Note. If the 'Hold' facility is inadvertently
left switched in, it is automatically cancelled after
a period of approximately 3 hours has elapsed.
Used for storing the programmed function parameters
Enter
and values in the instrument's nonvolatile memory.
✶
Note. The instrument responds instantly
to any programme change but the new value is
lost in the event of a power interruption if it has
not been 'Entered'.
Parameter Advance – used for selecting a particular
parameter from a programme page.
Used for increasing or decreasing a parameter value
or stepping up or down through a selection of
parameters applicable to a particular function.
✶
Note. Continued pressure on the 'Raise'
or 'Lower' switches causes the rate of change of
the displayed value to increase. To make small
adjustments, operate the switches momentarily.
Page Advance – used, via the security code, for
selection of individual programme pages.
chloride concentration,
5 ELECTRONICS SECTION
20-character
Alarm and Status
Dot-Matrix Display
Alarms
1
2
Mode
Cal
Fig. 5.2 Location of Controls, Displays and LEDs
5.5 Displays – Fig. 5.2
Two blue vacuum fluorescent displays are provided:
a) The upper is a 5-digit 7-segment type display which indicates
the measured variable.
b) The lower is a 20-character dot matrix type which provides
user information during setting up and in normal operation.
5.6 L.E.D. Indication – Fig. 5.2
There are 5 l.e.ds (indicators situated between the two displays)
which provide information on the current status of the monitor.
From left to right the indicators are as follows:
Used to indicate a concentration alarm state (either
A1 or A2
high or low). This indicator is used in association with
an external alarm relay output.
Used to indicate that the 'Hold' button has been
Hold
operated.
Indicates when a calibration sequence is taking place.
Cal
Indicates that the monitor was unable to carry out a
Fail
successful calibration.
5-digit Display
L.E.D.s
(Concentration)
Hold
Cal
Fail
Hold
Enter
Connections
Cover
9
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