Garnet SeeLevel II 900-D4S Single Manual page 7

Display Batteries: A set of four alkaline 'AA' cells in the display
enclosure powers all gauge display functions except for the 4-20
mA or 1-5V outputs. This allows for total stand alone operation
of the gauge. This battery pack should last from 3 to 4 years,
depending on usage of the LCD backlight. The batteries can be
field replaced with simple hand tools, and all programming is
retained when the batteries are removed.
Display Alarms: The display has 4 alarm points which can each
be programmed via the keypad to turn on or off at any level in
the tank. The alarm outputs are transistors which conduct to
ground, and are rated at 100mA at 24 volts. These outputs are for
connecting to an external alarm system which has been designed
to work with this type of output. The alarm outputs and ground
are available at a terminal block inside the display enclosure.
WARNING: The use of alarm points is entirely at the owner's
risk due to the nature of connecting external horns or lights,
the reliability of external horns or lights, and the requirement
for external switches to disarm them.
NOTE: The 900D4S is available from the factory with either a
4-20 mA output or a 1-5V output for volume and temperature.
Display 4-20 mA Outputs: The display has two 4-20 mA outputs
available at terminal blocks inside the display enclosure. One of
the 4-20 mA outputs is the volume; it derives its output value from
the volume display. 4.00 mA corresponds to an empty tank (for
example, 0 barrels) and the user sets the full scale (20mA) value
of the output. For example, if the user set the full scale at 400.0
barrels and the barrel reading was 300.0, then the 4-20 output
would be 16.0 mA (300/400*16mA+4mA). These outputs can also
be programmed to be off.
The other 4-20 mA output always indicates the temperature
as shown on the temperature display. An output of 4.00 mA
corresponds to -54.4°F (-48°C) and an output of 20.00 mA
corresponds to +233.6°F (+112°C), for a scale of 18.0°F/mA or
10.0°C/mA. This output scale cannot be changed by programming,
but it will be turned on or off with the volume 4-20 outputs.
These outputs must be provided with external power to operate.
A typical connection would be to connect an external +24 volts DC
power source to the positive 4-20 mA output terminal, and connect
the negative output terminal to the "hot" side of the remote
equipment load resistor. The other end of the load resistor goes to
ground. The current would produce a proportional voltage across
900D4S Manual Page 7