Watson-Marlow 720UN and 720SN User Manual
35
UN
16.1 Trim
When the pump is under remote control, it tracks an analogue signal from the user’s
remote control system to the
i/p
terminal of the Analogue 1 connectors at the rear
of the pump within the ranges 4-20mA, 0-10V or 1-5V. The
Trim
setup sequence al-
lows the user to customise the process-signal-to-pump-speed calibration. The se-
quence may be entered directly from the Setup menu or from the Analogue setup
menu.
Select
Trim
from the Setup menu or the Analogue setup menu using the
UP
or
DOWN
keys and press
ENTER
to confirm your choice.
Apply the low process analogue signal to the i/p terminal of the Analogue 1 con-
nector as instructed in the display. See 16.2
Analogue
. While the signal is being
applied, press
ENTER
to record the signal as a calibration point.
Apply the maximum process control signal. While the signal is being applied,
press
ENTER
to record the signal as a calibration point.
Apply 50% of the maximum process control signal. While the signal is being ap-
plied, press
ENTER
to record the signal as a calibration point.
If a mistake is made, press
STOP
at any point in the sequence, and the pump
displays the previous screen.
The final press on
ENTER
causes the pump to display a confirmation screen and
then redisplay the screen from which it entered the trim sequence: the Setup
menu or the Analogue setup menu.
The pump calculates a linear response from low to mid and from mid to high, and
records the results as a new analogue input calibration graph.
If any of the three signals match, a warning screen is displayed before the confirma-
tion screen appears, and the trim is ignored.
Note
: By applying the maximum process control signal when the minimum is re-
quested and vice versa, inverted responses can be set up.
Note
: Resetting factory defaults clears the trim calibration values.
