Reference, Installation, and Operations Manual

Section 6: Meter operation

3-9000-743 Rev S

June 2013

 

 

 

Frequency value data points

The value of each frequency output is readable via a data point (Freq1ChnlA, Freq1ChnlB, Freq2ChnlA, and Freq2ChnlB).

Volumetric flow rate content output scaling

When the frequency output pair represents either uncorrected or corrected volumetric flow rate (selected via the FreqXContent data point), then the full-scale volumetric flow rate is specified via the FreqXFullScaleVolFlowRate data point. This is the volumetric flow rate that corresponds to the selected maximum frequency and determines the frequency output pair’s K-Factor value (readable via the

FreqXKFactor data point). The minimum frequency output (0 Hz) corresponds to zero flow rate.

Velocity content output scaling

When the frequency output pair represents either average gas or sound velocity (selected via the FreqXContent data point), then the maximum scale velocity is specified via the FreqXMaxVel data point and the minimum scale velocity is specified via the FreqXMinVel data point. These points respectively correspond to the maximum frequency output (selected via FreqXMaxFrequency) and the minimum frequency output (0 Hz).

Energy rate output scaling

When the frequency output pair represents the energy rate (selected via the FreqXContent data point), then the full-scale energy rate is specified via the FreqXFullScaleEnergyRate data point. This is the energy rate that corresponds to the selected maximum frequency and determines the frequency output pair’s “energy K-Factor” value (readable via the FreqXEner- gyKFactor data point). The minimum frequency output (0 Hz) corresponds to zero energy rate.

Mass rate output scaling

When the frequency output pair represents the mass rate (selected via the FreqXContent data point), then the full-scale mass rate is specified via the

FreqXFullScaleMassRate data point. This is the mass rate that corresponds to the selected maximum frequency and determines the frequency output pair’s “mass K-Factor” value (readable via the FreqXMassKFactor data point). The minimum frequency output (0 Hz) corresponds to zero mass rate.

Frequency feedback

Frequency feedback is applicable only when the frequency represents a rate (actual or standard volumetric flow rate, energy rate, or mass rate). When frequency feedback is used, the frequency output signal is fed-back into the processor so that error (due to frequency quantization) can be corrected. Frequency quantization is what happens when the desired frequency cannot be exactly represented (since infinite granularity cannot be achieved). The FreqXFeedbackCorrectionPcnt data point specifies the percentage of the error correction. Typically, this percentage is quite small since in most cases the error is quite small and fluctuates “naturally” about zero. This point is not modifiable via the Daniel MeterLink Field Setup Wizard but is editable via the Edit/Compare Configuration screen. It is recommended that the FreqXFeedbackCorrectionPcnt not be modified from its default value of 1%. Setting FreqXFeedbackCorrectionPcnt to zero effectively disables frequency feedback.

Frequency outputs

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