13
To gain access to the security code link, remove
the instrument control cover, and if fitted unplug
the external switch connector. The security code
override link is located on the inner row of five pins
as shown in Fig 7.
Fig 7 Location of security code override link
6.10 Over and under-range
If the indicator display range is exceeded, the four
least significant digits will be blanked. Under-
range is indicated by '-1' and over-range by '1'.
Under and over-range are also indicated if the
input current falls below approximately 3.5mA or
rises above approximately 21mA.
If the input current falls below 3mA the instrument
initialisation sequence is performed as described
in section 2.
7. CALIBRATION EXAMPLES
The following examples illustrate the two ways in
which a BA324D indicator may be calibrated.
7.1 Using an external current source
The BA324D indicator is required to display:
-50.0
with a 4mA input
1050.0
with a 20mA input
from a linear transducer. Maximum display
resolution is required, the frequency of the mains
supply is 50Hz and the existing security code is
1209. In the operating mode the indicator is
required to display the input current as a
percentage of span when the
P
push-button is
operated.
Step 1
Connect indicator to calibrator
Connect the indicator to an accurate
external current source. Terminal 1
positive. The indicator will
automatically perform the initialisation
routine described in section 2, and then
display the input current using the
existing calibration information.
Step 2
Enter programming mode
With an input current between 4 and
20mA put the indicator in the
programming mode by simultaneously
pressing
P
and
E.
The indicator will
respond by displaying 'COdE'. Press
P
to clear this prompt and set the display
to the security code 1209 using the
Up
,
Down
and
P
push-buttons. Pressing
E
will enter the code, and after a few
seconds during which the decimal
points will be scrolled, the first
parameter 'root' in the main menu will
be displayed.
Step 3
Square root extraction
With 'root' displayed, press
P
which
will reveal the root extractor status.
The root extractor can be turned on or
off by the
Up
or
Down
buttons. Select
'OFF', and press
E
to return to the main
menu.
Step 4 Select frequency of maximum
mains (line) rejection
Scroll though the main menu until
'Cond' is displayed. Enter the sub-
menu by pressing
P
twice
and select
the 'FrE' function. Using the
Up
or
Down
buttons select '50', and then
press
E
twice to return to the main
menu.
