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Configuration using the PC 4-9
B1272M001 BARNETT ENGINEERING LTD. ProTalk Cv2
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 -40
o
C to +60
o
C.
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
0 as the minimum, 10 as the maximum, with Units set to read ‘thousand’ as the
prefix before gallons.
Once the range of the decimal scale has been entered, then the high and low setpoints
can follow. Both setpoints can be used within a single point. If the low setpoint is
not required, set it to the decimal minimum; if the high setpoint is not needed, set it
to the decimal maximum.
Default Decimal Values: