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Reference Manual
IP2048/RM, Rev AA
Section 5: Service and Troubleshooting
February 2015
5.4.9 Learn about echoes from false targets
Screen display: Lrn
The MSP400RH and MSP900GH has an easy-to-use “Lrn” (Learn) routine that allows the
instrument to learn up to four false echoes, which can then be ignored in future operations.
If the application is simple and there are no false echoes, press the green button
to exit the
menu and return to the PV display.
After the transmitter is in operational, if an echo other than the true liquid surface echo is
detected and an incorrect level reading is indicated, the instrument can learn to ignore this false
echo. The “Lrn” routine may be used at any time, either during or after setting-up or if a
problem occurs later.
Note
This menu option is in the engineering menu “Eng”. See “Accessing the engineering
menu” on page 49 or see Figure C-3 on page 79 for a map of the menu structure.
To store a false target echo
1. After entering the “Eng” menu (see the note above), press the green button
repeatedly until “Lrn” is indicated.
2. Press the blue button
to enter the “Lrn” menu. The display indicates “LrnX” where
“X” (0 to 4) is the number of stored false target echoes.
3. To store a new false echo, press and hold the blue button
for five seconds.
4. The display alternately flashes “Lrn” and the false target position. After four seconds,
the false target position is stored and the display re-indicates “LrnX”.
5. Press the red button
to save this false echo and exit to the menu. If this false echo
shouldn't be saved, press the blue button
to exit the menu.
6. To store another false target echo, re-start at step (2).
7. To get to the next menu option, press the green button
.
Note
If there are four false echoes stored (“Lrn4”), the transmitter will not allow another
echo to be stored until the memory is cleared (see procedure below).
When a false echo is stored, the transmitter sets up a 'window' around the false target
and ignores any echo from that window, unless the echo received from the liquid
surface is larger than the stored false echo. There may be no change in the transmitter
output current while the liquid level moves through this window, which is equivalent to
a distance of 20 cm.