FUTEK IPM500 (D500) Digital Display - Manual (Page 56)

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Scaling, Reading Coordinates of 2 Points Method
A scaling method, where the low and high input values are determined from
actual signals. A known low signal is first applied to the meter, such as the
output of a pressure transducer at zero pressure. That signal is captured as the
low input value, and the desired low reading is entered. A known high signal is
then applied, such the output of a transducer for a know weight or pressure.
That signal is captured as the high input value, and the desired high reading is
entered. The meter then applies straight line fit. This scaling method has the
advantage of calibrating the transducer and meter as a system. The actual
voltage or current at either point does not need to be known. The decimal point
is set by the separate dEC.Pt menu item.
Setpoint A value compared to the reading to determine the state of a relay. Term often
used interchangeably with “alarm setpoint.” The relay action can by latching or
non-latching
, utilize a hysteresis band, or utilize a deviation band. Hysteresis
bands and deviation bands are specified by two symmetrical limits around the
setpoint
.
Span The number of counts corresponding to a given signal range.
Tare
A rear panel input which causes the display to be set to zero when the input is
momentarily tied to logic ground by a switch or is held at 0V (logic level true).
When the input is allowed to float or is held at +5V (logic level false), the meter
displays readings relative to this new zero. A common application is in
weighing, where an external Tare button is pressed to read the weight of an
empty scale (tare), and tare is then automatically subtracted as a constant from
gross weight for display of net weight. Tare can also be used for other appli-
cations where a reading relative to starting point is desired.
Valley Display
The minimum (or most negative) reading since that minimum was last reset.
Reset can be via the meter front panel, an external input, or a software
command. The displayed value can reflect the filtered or unfiltered readings.
Zero
When used with process meters, zero is an adjustment so that a given low
transducer output reads zero on the meter. Zero is adjusted by programming
offset
.
Copyright 1993-2009 FUTEK Advanced Sensor Technology REV 11/09/09