BEKA BA374C, Manual, Page: 16 / 27

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 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 .
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 internal references are used for calibrating
the BA374C transmitter they may require periodic
checking against external standards. Annual
checks will produce acceptable performance,
although less frequent checks are usually
adequate.
If the BA374C 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 BA374C 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.
6.8.1 Conditioning internal references: 'Cond'
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.
These functions are contained in a protected
sub-menu to minimise the possibility of accidental
adjustment. Select 'Cond' from the menu and
press
P . The transmitter will display '0000'. Using
the Up and Down buttons and the P button to
move to the next digit enter the password 'SurE.
(Note that 'S' is entered as '5') There is a ten
second time-out on password entry. Pressing
E
will then give access to the sub-menu containing
the four refences.
6.8.2 Voltage input reference 'U.IP'
With the BA374C input terminals connected to
accurate voltage calibrator, select 'U.IP' from the
'Cond' sub-menu and press
P. The transmitter will
respond by displaying 'Lo' which is a request for an
accurate -75.000mV input. Adjust the external
voltage calibrator to supply -75.000mV and press
P to store this figure in permanent memory. The
transmitter will display scrolling decimal points
while the reference is being updated and will then
return to the 'Lo' prompt.
Select 'Hi' from the sub-menu which is a request
for an ac75.000mV input. When the input
is correct press
P to store this figure in permanent
memory. The transmitter will display scrolling
decimal points while the reference is being
updated and will then return to the 'Hi' prompt.
This completes adjustment of the voltage input
reference.
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