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CHAPTER 2
SYSTEM DESCRIPTION
The SeeLeveL consists of a display unit that mounts inside the RV, and sender panels
that stick to the side of the holding tank. A single two conductor wire is used to
connect all the sender panels to the display.
The Sender: Each sender panel is a flexible self adhesive printed circuit board which
is stuck to the side of the holding tank. The sender panel can be cut to length to
match the height of the tank, and it auto calibrates itself so that it can read from Empty
to Full regardless of the height of the tank. The sender scans the water level through
the tank wall using patented digital techniques programmed into the sender
microprocessor. When the sender transmits the water level information to the display,
it sends a digital code that has built in error detection, making it impossible for the
display to read an incorrect level, even if the wiring is bad. In addition to the level, the
sender also transmits diagnostic information about its operation. This information can
be used to determine if there is buildup of sludge on the inside of the tank, or to
determine if the sender is delaminating from the side of the tank. If sludge buildup in
the tank becomes extreme the gauge will cease to operate (the tank will always read
empty), so by monitoring the signal level the tank can be cleaned before the buildup
gets excessive. If the tank is more than 12 inches tall, two senders can be stacked to
allow measurement of levels up to 24 inches.
The Display: The display receives the information from the three sender panels via a
single two conductor wire, and displays the level information in percent of full on a
three digit LED display. When the front panel button for a particular tank is pressed,
the display powers up and displays the level for that tank. If the button is pressed and
released, the display will show the level for about 5 seconds and then shut down
automatically. If another button is pressed before the display shuts down, then the
new level will immediately be shown. If the same button is pressed twice, the display
will hold on that tank and continue to show updated levels for 5 minutes before
shutting off. This allows the user to monitor the filling or draining of a tank. By
pressing two buttons at once, the diagnostic functions can be accessed; these are
described in detail in the troubleshooting chapter.
If a sender is operating properly and connected to the display with good wiring, then
the display will show the level normally. If the wiring is disconnected, shorted, or cut,
or if the sender panel is defective, then the display will indicate an error code. The
various error codes are shown in the troubleshooting chapter.
With these diagnostic features and the digital nature of the tank level sensing
technology, it is almost impossible for the system to indicate an incorrect water level,
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