Xylem FC220 OPEN CHANNEL FLOW MONITOR - Manual (Page 10)

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VIII. Power Saving Mode
A power saving mode is provided that allows the operating current to be reduced in
remote monitoring applications. One way this is accomplished is to turn off the LCD
display backlight, this saves about 20mA of current. Three modes allow the user to
turn the backlight on all the time, off all the time, or turn it on for one minute only. In
this last mode, the backlight will come on for one minute when any of the buttons on
the keypad are pressed, then turn off again. The water level sensor can also be turned
on and off periodically to reduce power consumption. The user can program a sample
rate of 0-60 minutes, and can set the sensor warm-up time of 0-60 seconds. Example:
The sample rate is 30 minutes and the warm-up time is 3 seconds. The sensor will be
turned on for 3 seconds every 30 minutes then shut off again. During the time the
sensor is off the flow display and 4-20mA output will indicate a flow based on the last
level reading. The totalizer will continue to be incremented, and the relays will
continue to operate, based on that last reading. After 30 minutes more, a new reading
will be taken and the display and 4-20mA output updated again. Note that using the
4-20mA output will increase the current draw by an amount equal to the output
current.
IX. Scientific Notation
Scientific notation is generally used for displaying very large or very small numbers.
It represents a number as being multiplied by 10 raised to a power, such as 5.67*10^2
being equal to 567 since 10^2 equals 100 (10^2 = 10²). Engineering notation is similar
but only uses 10 raised to a power that is a multiple of 3; like 10^3 (one thousand),
10^6 (one million) or 10^9 (one billion). This notation also replaces “*10^” with “E”
(Exponent) so that 5.67E2 is equivalent to 5.67*10^2 or 567. The notation E2 is also
equivalent to “shift the decimal point to the right two times”. This makes the display
of large numbers easier to read; 5.67E3 is 5.67 thousand or 5670, 5.67E6 is 5.67
million, etc. In the same way, small numbers less that one can be shown as 10 raised
to a negative power, or “shift the decimal point that many times to the left”; such as
5.67E-3 = 0.00567 or 5.67 thousandths, 5.67E-6 = .00000567 or 5.67 millionths.
X. Totalizer
A 9-digit totalizer keeps track of the total volume of water that has accumulated since
the last time the totalizer was reset. The totalizer display supports engineering notation
and can store volumes up to 1.1E12 cubic feet (1.1 x 10^12 or 1.1 trillion) in any of the