19
8. CONFIGURATION EXAMPLE
In this example a BA474ND indicating temperature
transmitter is required to display temperature in
degrees Celsius with maximum resolution. The
temperature sensor is a 3 wire Pt100 resistance
thermometer and the 4/20mA transmitter output is
required to representing –10 to +250
o
C. . A left hand
justified bargraph representing 100.0 to 200.0
o
C is
required. Resistance thermometer failure is to be
indicated by an overrange output current of 21.0mA.
After configuration access to the configuration menu
is to be protected by code 1209.
Configuration is performed using the four push
buttons which are located behind the removable
switch cover below the digital display – see Fig 7.
The BA474ND can be supplied with factory fitted
external push buttons if frequent adjustments are
required.
The transmitter configuration may also be performed
via HART
communication from a local or remote
configurator. The HART
communication protocol
includes additional functions allowing the complete
temperature loop, including the temperature sensor
and the transmitter load, to be calibrated, see the
BEKA HART
Interface Guide which may be
downloaded from www.beka.co.uk/manuals
Step
1
Access the configuration menu &
select the type of input.
See: Fig 7 and section 7.2.1
New BA474ND indicating temperature
transmitters are supplied conditioned
with default access code ‘0000’ that
allows unrestricted access to the
configuration menu.
To enter the configuration menu press
buttons
P
and
E
simultaneously which
will cause the first prompt ‘InPut’ to be
displayed. Press
P
to enter the function
and the transmitter will display the
current type of input. To configure the
transmitter to operate with a three wire
resistance thermometer press the
▼
or
▲
button until ‘3rtd’ is displayed. When
selected press
E
to enter the selection
and return to the ‘InPut’ prompt in the
configuration menu.
Step 2
Select resistance thermometer type
See: Fig 7 and section 7.2.10
Using the
▼
or
▲
button select the
‘r,tYPE’ prompt from the configuration
menu and press
P
to enter the function
which enables the type of resistance
thermometer to be selected. The
transmitter will display the existing type
of resistance thermometer, using the
▼
or
▲
button select ‘100r’ which is the
required Pt100 sensor. Enter the
selection by pressing the
E
button that
will return the display to the ‘r.tYPE’
prompt in the configuration menu.
Step 3
Select units of digital display
See: Fig 7 and section 7.2.3
Using the
▼
or
▲
button select ‘dEG’
from the configuration menu and press
P
to enter the function which enables the
digital display units of measurement to
be selected. Using the
▼
or
▲
button
scroll through the options and select ‘ºC’
which represents degrees Celsius.
Press
E
to enter the selection and return
the transmitter display to the ‘dEG’
prompt in the configuration menu.
Step 4
Select display resolution
See: Fig 7 and section 7.2.4
Using the
▼
or
▲
button select ‘rESn’
from the configuration menu and press
P
to enter the function which determines
the resolution of the digital display.
Using the
▼
or
▲
button select ‘Hi’ to
provide the required 0.1 resolution
display. Press
E
to enter this selection
and return the display to the ‘rESn’
prompt in the configuration menu.
Step 5
Sensor fault detection
See: Fig 7 and section 7.2.6
Using the
▼
or
▲
button select ‘FAuLt’,
the input sensor fault detection function,
from the configuration menu and press
P
. Using the
▼
or
▲
button scroll
through the options and select ‘uP 21’
which forces the output current to
21.0mA when a sensor failure is
detected. Enter the selection by
pressing
E
which will also return the
transmitter display to the ‘FAuLt’ prompt
in the configuration menu.
Step 6
Configuration of 4/20mA output
See: Fig 7 and section 7.2.7
The BA474ND transmitter input at which
the transmitter output current is 4mA
and 20mA is defined by the ‘CAL’
function which contains two sub-
functions.
Using the
▼
or
▲
button select ‘CAL’
from the configuration menu and press
P
which will show the ‘ZEro’ sub-function
prompt. Press
P
again to enter this sub-
function, which will reveal the existing
input at which the transmitter output
current is 4mA. Adjust the display to
the required –0010.0 using the
▼
or
▲
button to adjust the flashing digit and the
P
button to move control to the next
digit. A negative display is achieved by