Press
P
to show the transmitter display at which
the output current is 20mA. The flashing digit of the
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 the least significant digit has been adjusted,
press
E
to return to the 'SPAn' prompt.
Note:
If a complete loop including a primary
element, BA378C temperature transmitter and a
load are being calibrated, the Trim Menu is the
preferred method. It allows the transmitter display
and output current to be adjusted to compensate
for inaccuracies in the other components in the
loop. Details of the trim menu are contained in
section 7 which also describes periodic calibration.
6.7 Security Code 'COdE'
Access to the Programme and Trim Menus may be
protected by a four digit numerical security code
which must be entered before access is granted.
New instruments are programmed with the default
security code 0000 which allows unrestricted
access to both menus.
To enter a new security code select 'COdE' from
the Programme Menu and press
P
which will cause
the transmitter to display the current security code.
Each digit of the code can be changed using the
Up
and
Down
push-buttons, and the
P
button to move
to the next digit. When the required code has been
entered press
E
to return to the main menu. The
revised security code will be activated when the
transmitter is returned to the display mode.
If the security code is lost, access to the
programme and Trim Menus can be obtained by
putting the internal security link in the override
position - see Fig 8. The security code can then be
viewed by selecting 'COdE' from the menu and
pressing
P
.
To access the security code link un-plug the
removable terminal(s) from the rear of the
instrument by gently pulling, and remove the
instrument rear panel which is secured by six
screws. The link can then be moved to the override
positioned as shown in Fig 8.
Fig 8 Location of security code override link
6.8 Calibrating the internal references
WARNING!
Changing the internal references will
alter the instrument performance. Do
not attempt to recalibrate these
references unless you have adequate
test equipment and have read the
following instructions. For routine
calibration of the instrument use the
Trim Menu described in Section 7.
If the Trim Menu is
not
used for routine calibration
of the BA378C transmitter, for maximum accuracy
the internal references may require periodic
checking against external standards. Annual checks
will produce acceptable performance, although less
frequent checks are usually adequate.
If the BA378C transmitter is calibrated against an
external voltage, resistance or temperature
calibrator using the Trim Menu, the internal
references should never need re-calibrating.
Details of the Trim Menu are contained in
section 7.
There are four internal references:
Voltage input
3-wire RTD
4-wire RTD
Current output
The input voltage reference must be adjusted first
irrespective of the transmitter application, but it is
only necessary to adjust the other three references
if the function to which they relate is being used.
For example, a BA378C with a thermocouple input
from which the 4/20mA output current is being used
would require the voltage input and the current
output reference adjusting.
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