14
The grand total counter can only be reset to zero
from the 'CLr.Gtot' function within the main
programme menu. To zero the grand total
counter select 'CLr. Gtot' and press P which will
cause the instrument to display 'Clr. no' with 'no'
flashing. Press the Up or Down button until 'CLr.
YES' is displayed followed by P which will result in
a '0000' prompt. Using the Up and Down buttons
and the P button to move to the next digit, confirm
the request by entering the password 'SurE'. Note
'S' is entered as '5'. Pressing E will then reset the
grand total counter to zero and return the
instrument to the 'CLr. Gtot' prompt in the main
menu.
WARNING
After resetting the grand total counter to
zero the old grand total can not be
recovered.
5.11 Timebase: t-bASE
Together with the total scale factor 'SCALE-t', this
function defines the arithmetic relationship
between the rate and total displays. The
timebase divides the rate display by 1, 60 or 3,600
depending upon whether the BA558C rate display
represents flow 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 buttons will index though the following three
options.
BA558C
Rate
display
represents
flow
Select
In
t-base
menu
Total display
= rate
divided by
Per second
tb – 1
1
Per minute
tb – 60
60
Per hour
tb – 3600
3600
Select the required divisor and press E to return to
the main menu.
5.12 Function of the
P
push-button:
C - - P
This parameter defines the function of the P push-
button when the BA558C is in the display mode.
Either the input current in milliamps or the input as
a percentage of span may be shown.
To check or change this parameter select 'C - -P'
from the main menu and press P to reveal the
current setting. Pressing the Up or Down button
will toggle the instrument between the two options.
Select '4-20' if the input current in milliamps is
required, or 'PC' if the input as a percentage of
span is required. When the required option is
displayed press E to store the selection and return
to the main menu.
Accuracy of both these options depends upon the
accuracy of the internal references which should
be periodically calibrated - see section 5.9.2
5.13 Total scale factor: SCALE-t
Together with the timebase 't-bASE', this is a
dividing factor which defines the arithmetic
relationship between the rate and total displays.
The total scale factor may be set to any value
between 0.0001 and 65535* allowing the total flow
and rate of flow to be displayed in different
engineering units.
SCALE-t = Units of rate display
Units of total display
When calculating SCALE-t the required units of
measurement for the total display must be
converted to those used for the rate display as
shown in following example:
The BA558C rate display represents litres per
second but the total flow display is required in UK
gallons. There are 4.5461 litres in a UK gallon.
SCALE-t = Units of rate display
Units of total display
= 1 litre = 1 litre
1 gallon 1/(4.5461) litres
SCALE-t = 4.5461
