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6. PROGRAMMING & CALIBRATION
The BA338C is programmed and calibrated via
four front panel push-buttons. All the programming
functions are contained in an easy to use menu
that is shown diagramatically in Fig 9. Each
function is summarised in section 6.3 and includes
references to more detailed information. Although
this simple menu driven system enables most
adjustments to be made without repeated
reference to this manual, it is recommended that at
least the summary of the programmable functions
in section 6.3 is read before attempting
programming or recalibration.
When the BA338C is fitted with alarms, 4/20mA
output or a pulse output, the basic menu is
expanded to include the option(s). Section 9 of
this manual explains how to programme these
additional functions.
Note:
While the instrument is being programmed
or calibrated, totalisation continues so that any flow
occurring during this time is recorded.
6.1 Calibration structure
Fig 8 shows the BA338C calibration structure. The
rate and total display calibration functions are
totally independent allowing the displays to have
different engineering units.
For the rate display the pulse input is scaled by
SCALE-r to represent engineering units and
multiplied by the timebase t-bASE to calculate and
display the rate of flow per second, minute or hour.
Similarly, to calculate the total flow in engineering
units the number of input pulses is divided by the
total scale factor SCALE-t. Total flow is
continuously added to the grand total.
The BA338C displays ‘real’ decimal points. Moving
the position of a decimal point in a scale factor will
therefore affect the instrument calibration.
The BA338C updates its total flow calculation twice
per second. If the instrument is used for batching
applications, this resolution may define the
accuracy of the system.
Note:
The total and rate displays may be updated
less frequently depending upon the display update
time selected.
Fig 8 Calibration structure
6.2 Accessing programming functions
Throughout this manual push-buttons are shown in
italics e.g. P or Up push-button, and legends
displayed by the instrument are shown within
inverted commas e.g. 'CAL' and ' ALr2'.
Access to the programme menu is obtained by
operating the P and E push-buttons
simultaneously. If the instrument is not protected
by a security code the first parameter 'UPdAtE' will
be displayed. If a security code other than the
default code 0000 has already been entered, the
instrument will display 'COdE'. Press P to clear
this prompt and enter the security code for the
instrument using the Up or Down push-buttons to
adjust each digit, and the P push-button to move
control to the next digit. If the correct code has
been entered pressing E will cause the first
parameter 'UPdAtE' to be displayed. If an incorrect
code is entered, or a push-button is not operated
within ten seconds, the instrument will
automatically return to the display mode.
Apart from defining the position of the decimal
point in the rate display all programme functions
and prompts are shown on the large eight digit
display.
Once within the main programme menu the
required parameter can be reached by scrolling
through the menu using the Up and Down push-
buttons as shown by the programme structure in
Fig 9.
