August 2020
Reference Manual
L231040 Rev AD
19
Local display
showing dark
black squares or
blinking "please
standby"
LCD did not initialize
properly
Cycle power rapidly
(this may have to
be done a few
times).
Electronics module
failure
Replace electronics
with known
working electronics
from a sensor of
similar length
and/or contact
factory for
replacement
assistance.
Cannot enter into
menus local
display menus
using push
buttons
Write protect jumper
is locking buttons
Move the blue
jumper from the
right
(2pins) to the left
(2pins).
Transmitter output
does not match
display
If the mA output
greater than
22mA then
Electronics module
failure (most likely
due to power surge)
Consult factory for
replacement
assistance
(non-warranty)
If the mA output less
than 22mA
but slightly different
from
display then DAC
Trim
Perform DAC trim
described in section
7.1.
6.3 Changing Signal Parameters
There are 3 parameters involved with “Energy Settings”.
These parameters are Energy, DCOffset and HoldTime.
•
Energy [%] is the amount of energy (a voltage
correlated to percentage) being sent down the
sensor probe.
•
DCOffet [V] is the DC voltage that the signal is
offset by. It is useful for eliminating some noise.
•
HoldTime [µs] is how long the Energy is sent down
for.
Symptom: Transmitter is erratic (i.e. output going
from correct reading to failure mode).
Possible Resolution:
Increase Energy Settings:
1. Unlock the pushbuttons by moving the blue jumper
to the left, Hold the UP button for 1sec
2. While holding the UP button also hold ENTER
button (together) for 3 secs
3. The menu should change to “ComPort” release the
buttons
4. Bypass this menu by pressing enter.
5. Keep bypassing the menus until you see “ChgSgnl”,
6. Use the up or down arrows to change the “no” to a
“yes” and press enter.
7. The next Menu will say “Energy” and a
percentage, increase this number by 10 [%] and
press enter. (i.e. 20 to 30 %)
8. The next Menu will say “DCOffset”, and a voltage,
leave this value unchanged and press Enter.
9. The next menu will say “HoldTime” and a number;
increase this number by 2 [µs] and press enter.
(i.e. 4 to 6 µs)
10. Then simply press enter until you see the “Exit”
menu and then press enter one last time.
The above procedure can also help if the output is in
constant failure mode. If the procedure does not help
please contact factory for further assistance. 1-800-221-
3653.
Section 7: LTM-350 has HART Protocol
7.0 Hart Protocol: General Information
The LTM-350 is a HART registered and certified instrument.
The section presents how the HART Communication
Protocol has been utilized in the LTM-350. This section
does not explain what HART Protocol is, please visit
www.hartcomm2.org to learn about HART.
