9
Display
Description of function
'rEF'
Calibration of internal references
The indicator contains two references
representing a 4 and 20mA. input
These enable the BA324ND display to
be calibrated without the need for an
external calibrator, or disconnection
from the 4/20mA loop. See the SEt
function.
If the SEt or C--P functions are to be
used, the internal references should
be periodically calibrated.
See section 6.7.2
'C - - P' Function of P push-button
The BA324ND may be programmed
to display the input current in
milliamps or the input current as a
percentage when the
P
push-button
is operated.
See section 6.8
'COdE'
Security code
Defines a four digit numeric code
which must be entered to gain access
to programmable functions. Default
code 0000 disables the security
function and allows unrestricted
access to all programmable functions.
See section 6.9
6.2 Root extractor: root
This function is primarily intended for use with
differential flowmeters which have a square law
4/20mA output. To activate the square root
extractor select 'root' from the menu and press
P
which will reveal if the function is 'On' or 'OFF'. If
the function is set as required, press
E
to return to
the menu, or press the
Up
or
Down
button to
change the setting, followed by the
E
button to
return to the main menu. For reference, the
following table shows the output current from a
non-linearised differential flowmeter. Below 5% of
flow the BA324ND display is forced to zero.
% of full flow
Current output mA
5.0
4.04
10.0
4.16
25.0
5.00
50.0
8.00
75.0
13.00
100.0
20.00
6.3 Resolution: rESn
This function defines the resolution of the least
significant display digit. Decreasing the display
resolution can improve the readability of a noisy
signal. Select 'rESn' from the menu and press
P
which will reveal the current display resolution. To
change the resolution press the
Up
or
Down
button
to select 1, 2, 5 or 10 digits, followed by the
E
button to return to the menu.
6.4 Position of the decimal point: d.P.
A dummy decimal point can be positioned between
any of the digits or may be absent. To position
the decimal point select 'd.P.' from the menu and
press
P
. The decimal point can then be moved or
turned off by pressing the
Up
or
Down
push-
button, followed by
E
to return to the menu.
6.5 Calibration of display using an external
current source: CAL
This function enables the zero and span of the
indicator to be adjusted using an external
calibrated current source. When used with an
accurate traceable current source this is the
preferred method of calibration.
To calibrate the indicator select 'CAL' from the
main menu and press
P
. The indicator will display
'ZErO' which is a request for a 4mA input current.
Adjust the external current calibrator to 4.000mA
and again press
P
which will reveal the current
zero display. Each digit of the indicator display
can be changed by pressing the
Up
or
Down
buttons. When the first digit is correct pressing P
will transfer control to the next digit.
