11
Display
Description of function
'FrE'
Frequency rejection
Defines the mains (line) frequency at
which the indicator has maximum ac
rejection. 50 or 60Hz may be selected.
This function must be set before the
instrument is calibrated as it affects the
indicator display.
See section 6.7.1
'rEF'
Calibration of internal references
The indicator contains two references
representing 4 and 20mA. These
internal references are used when the
indicator display is calibrated without
an external current calibrator, and
when the input current is displayed in
milliamps. See the SEt and C--P
functions. If either of these functions is
to be used, the internal references
should be periodically calibrated.
See section 6.7.2
'C - - P'
Function of
P
push-button
The
P push-button may be
programmed to display the input
current in milliamps or the input current
as a percentage of the displayed span.
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.
% of full flow Current output mA
2.5
4.01
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 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. When all the
digits have been adjusted, press E to enter the
new zero. The indicator will display 'Ent' for a few
seconds while the information is being stored in
memory, and will then return to the 'ZErO' prompt .
