LORD V-Link-200, Руководство пользователя

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V-Link
®
-200
User Manual
Scale the (gained) sensor input voltage/EU ratio to the node input voltage/EU ratio to determine the
equivalent node FSO value (
x).
2.256 V/250 psi = 4.096 V/x
(250 psi * 4.096 V)/2.256 V = x = 453.9 psi
The node converts voltage inputs to A/D values. For an 18-bit node, there are 262144 A/D values
over the 4.096 V input range. Divide the node EU FSO by the A/D value to get the ratio, or slope, of
EU to A/D value.
453.9 psi/262144 bits = 0.00173 = slope
Once the slope is entered, the sensor offset value can be measured in a data sampling session,
such as streaming. Sample the sensor channel with no load applied, and read the EU value. Enter
this as a negative value for the offset in order to have it subtracted from readings.
7.2 Sensor Conversion Values
NOTE
In order to report accurate readings, many sensors require calibration. Calibration
coefficients normalize the sensor output to a known reference device and are often expressed
in the measurement unit conversion values; the only difference being the use of a traceable
reference. Calibration can be used to account for the variations between individual sensors,
wiring, system electronics, sensor mounting and environmental conditions.
The conversion values include the slope, offset, gain, scale, and formula for converting the sensor
A/D value (bits) to engineering units. The bits are the digital representation of the sensor voltage
output. The type of sensor, channel, and desired engineering units determine what conversion
values are available. The conversion values are entered through SensorConnect and saved in the
node memory for the applicable channel.
Conversion values for the V-Link-200 are determined mathematically from the sensor sensitivity
specifications, from the sensor manufacturer calibration data, or through a calibration process.
Calibration incorporates coefficients that normalize the sensor output to a known reference device
in order to guarantee accuracy of the sensor readings, especially when making small or precise
measurements. See Sensor Calibration on page 55 for more information. Not all sensors require
calibration.
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