12
buttons simultaneously will exchange the
displays.
Note:
Both decimal points must be
repositioned after the displays have been
exchanged.
5.7 Lower display: ‘dISPLAY.2’
This function turns the lower display on or off.
When turned off, the BA544D will only have
one eight digit display which may be
programmed to show total flow or rate of flow.
To check the status of the lower display select
‘dISPLAY.2’ from the menu and press
P
which
will reveal if the function is ‘On’ or ‘OFF’. The
settings may be changed by pressing the
Up
or
Down
button followed by the
E
button to return
to the menu.
5.8 Rate scale factor: ‘SCALE-r’
Together with the instrument timebase, this
function defines the arithmetic relationship
between the pulse input frequency and the rate
display. When used with a flowmeter SCALE-r
should be set to the K-factor of the flowmeter
i.e. the number of pulses the flowmeter
produces for a unit of flow. e.g. 45.6 pulses
per litre. See section 6 for a worked example.
SCALE-r is a dividing factor that may be
adjusted between 0.001 and 99999999.
To check or change the total scale factor select
'SCALE-r' from the main menu and press
P
to
reveal the existing setting, one digit will be
flashing. The value of the flashing digit can be
changed by pressing the
Up
or
Down
buttons.
When this digit is correct pressing
P
will
transfer control to the next digit.
To position the decimal point in the rate scale
factor, move the flashing digit to the left hand
side of the required decimal point position and
simultaneously press the
Up
and
Down
buttons.
When the required rate scale factor has been
entered, press
E t
o store the number and
return to the main menu.
5.9 Timebase: ‘t-bASE’
The timebase multiplies the rate display by 1,
60 or 3,600 depending upon whether the
BA544D is required to display rate per second,
per minute or per hour. See Fig 6.
To check or change the timebase, select
't-bASE' from the main menu and press
P
which will reveal the current setting. Pressing
the
Up
or
Down
button will index through the
three options:
tb-1
for flow / second
tb-60
for flow / minute
tb-3600
for flow / hour
Select the required multiplier and press
E
to
return to the main menu.
5.10 Rate filter: ‘FILtEr’
This digital filter has two independent
adjustable parameters enabling the rate
display frequency response to be tailored for
optimum performance.
The filter parameters are controlled by a two
digit number. The first digit defines the amount
of filtering applied to the display as shown
below.
First digit
Filter time constant
seconds
0X
0
1X
1.3
2X
4.3
3X
6.5
4X
8.7
5X
11.3
6X
15.7
7X
20.9
8X
25.2
9X
31.5
The second digit defines the deviation from the
displayed rate at which the filter will be
overridden and the rate display will move
rapidly to the new value.
Second
digit
Magnitude of step
change which will
produce a rapid
response
X0
Off
X1
1%
X2
2%
X3
4%
X4
8%
X5
12%
X6
16%
X7
24%
X8
32%
X9
64%
By careful adjustment of the two parameters a
stable display with an acceptable step input
response can be obtained for most
applications.
During commissioning it is recommend that
initially the second digit is set to 0 (off) and the
first digit is adjusted to provide acceptable rate
