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7. CALIBRATION EXAMPLES
The following examples illustrate the two ways in
which a BA324ND indicator may be calibrated.
7.1 Using an external current source
The BA324ND 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.
Step 5
Define function of P push-button
Select 'C--P' from the main menu and
press
P
to reveal the function of the
P
button in the display mode. Select
percentage 'PC' and return to the
main menu by pressing
E
Note:
Because an input current
display in milliamps is not required, it
is not necessary to calibrate the two
internal references.
Step 6
Position dummy decimal point
Scroll though the main menu until
'd.P.' is displayed and then press
P
.
Using the
Up
and
Down
push-buttons
position the dummy decimal point in
front of the least significant digit.
Press
E
to return to the main menu.
Step 7
Calibrate the display
Scroll through the main menu until
'CAL' is displayed. Press
P
and the
indicator will request a 4mA input by
displaying 'ZErO'. Set the input
current to 4.0000 ± 0.0004mA and
press
P
again which will reveal the
existing zero display. Using the
Up
,
Down
and
P
push-buttons enter the
required zero display of -50.0 Press
E
to return to the 'ZErO' prompt.
Press the
Up
push-button and the
indicator will request a 20mA input by
displaying 'SPAn'. Set the input
current to 20.0000 ± 0.0004mA and
again press
P
which will reveal the
existing display at 20mA. Using the
Up
,
Down
and
P
push-buttons enter
the required display of 1050.0
Press
E
twice to return to the main
menu.
Step 8
Return to the display mode
Following completion of calibration
return to the display mode by pressing
E.
