3: Operating Procedures
U3000/U4000 User Manual
25
(Issue 2.0)
3.
Connect a calibrated ammeter to the 4-
20mA output and adjust the
UP/DOWN
Scroll keys (Coarse) and
LEFT/RIGHT
Scroll keys 5 & 6 (fine) until the output is
exactly 4.00mA.
The DAC should indicate approximately
8000.
4.
Press
ENTER
when done.
5.
With the meter still connected to the 4-
20mA output adjust the Scroll keys to
obtain an output of exactly 20.00mA.
The DAC should indicate approximately
40000.
6.
Press
ENTER
when done.
4-20mA Signal scaling
Note: The 4-20mA can be set to represent a particular flow range. It is also possible to enter a negative figure
for the minimum output and this would enable a reverse flow to be monitored.
7.
With the instrument operating in the
FLOW
READING
mode, press the
4-20mA
function
key. This will access the
4-20mA OUTPUT
screen.
8.
Select
Flow at max. output
and press
ENTER, then
enter a value of the flow
rate that you want to associate with a
20.00mA output.
9.
Select
Flow at min. output
and press
ENTER
then enter a value of the flow rate
that you want to associate with a 4.00mA
output. This could be ‘0’.
10. Select
Output mA for error
and enter a value (max of about 26mA) that you want the 4-20mA
output to produce in the event of an error (e.g. if the flow-rate is outside the set range).
11. Upon completion press
ENTER
to return to the
FLOW READING
screen.
How to convert the measured current to flow rate
Assume the maximum flow rate is
F
max
(l/min) and the minimum flow rate
F
min
is ‘0’ (l/min), as shown.
CALIBRATE 4mA
DD-MM-YY HH:MM:SS
Dim: mm
Adjust the output current to 4mA
Use
UV
to set, 5/6 to trim
DAC Value: 8000
Press
when done
CALIBRATE 20mA
DD-MM-YY HH:MM:SS
Dim: mm
Adjust the output current to 20mA
Use
UV
to set, 5/6 to trim
DAC Value: 40000
Press
when done
4-20 mA OUTPUT
DD-MM-YY HH:MM:SS
4-20 mA O/P is ON
Dim: mm
mA Output Reading : 0.00
Output Range : 4-20
Units : l/min
Flow at max. output : 0.00
Flow at min. output : 0.00
Output mA for error : 22.00
Exit
4
8
12
16
20
F
max
Flo
w
(l
/min
)
I
(mA)
F
min
[0-16mA scale]
[0-20mA scale]
[4-20mA scale]
