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...5 ELECTRONICS SECTION
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 fluoride concentration, electrode
mV output, flowcell control temperature, sensor slope,
Mode
date, time, the time to the next calibration and the time
from 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.
10
20-character
Alarm and Status
Dot-Matrix Display
Alarms
1
2
Mode
Cal
Fig. 6.1 Overall Programme Chart
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 five l.e.d's (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
high or low). This indicator is used in association with
A1 or A2
an external alarm relay output.
Used to indicate when the 'Hold' button has been
operated.
Hold
Indicates when a calibration sequence is taking place.
Cal
Indicates when the monitor was unable to carry out a
successful calibration.
Fail
5-digit Display
L.E.D.s
(Concentration)
Hold
Cal
Fail
Hold
Enter
Connections
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