Barnett Engineering ARU CV2 instruction manual Calibrate, Binary Values, Decimal Values

Configuration using the PC 3-9

Calibrate

Calibration of an analog allows the conversion of the input voltage reading to a value that is expressed in engineering units. Setpoints are then assigned to the actual corresponding measurement, and when the point is interrogated, the reading is announced in engineering units. Calibrate is a secondary dialog box that is activated from the Analog Point dialog box.

The relationship between the binary reading from the input analog converter and the decimal value that is used for setpoints and annunciation is established by setting the Binary and Decimal limits.

Binary Values

The full scale binary range, when an input port is configured for analog operation, is determined by the internal A to D converter which provides eight bits of resolution. The minimum binary value is 0 and the maximum value is 255 for the input range of 0 to +5 VDC.

If the sensor that is driving the input port does not produce a full scale output that corresponds to the Cv2 range, then the binary values can be adjusted to match the sensor. For example, if a sensor with a full scale range of 1 volt to 5 volts is used, then set the Cv2 with the binary minimum at 51 (255 x 1/5) and the binary maximum at 255. If the sensor produces outputs of between 0 and 2.5 volts, then set the binary minimum to 0 and the binary maximum to 127 (255 x 2.5/5).

The range of the sensor should use as much of the available Cv2 analog input range as possible in order to maintain a high resolution for the readings.

The minimum and maximum Binary values will correspond to the Decimal minimum and maximum that represent the actual readings, in engineering units, being monitored by the sensor.

Default Binary Values: 0 for the minimum and 255 for the maximum.

Decimal Values

Decimal values represent the real physical measurement being monitored by the sensor. For example, the current or voltage signals correspond to some engineering value such as gallons or PSI.

Set the decimal minimum to the low end of the range being measured. Set the decimal maximum to the high end of the sensor scale.

For example, if the minimum for the sensor is 50 rpm and maximum is 800 rpm, enter these values in the decimal section. Decimal values may be negative, e.g. a temperature range of -40oC to +60oC.

The range allowed for the decimal limits is -999.9 to +999.9. If values greater than these settings are needed, use a suitable prefix or suffix from Units and scale the reading to fit in the allowed range. If a sensor was connected to a meter with a range of 0 to 10,000 gallons per hour, then a suitable scale in the decimal values would be

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