Emerson Process Management rosemount 3300 series manual

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00809-0100-4811, Rev AA October 2002

Rosemount 3300 Series

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In interface applications where the bottom product has a low dielectric constant, or if the signal is attenuated in the upper product, the amplitude of the reflected signal is relatively low and difficult for the transmitter to detect. In such a case it may be possible to detect the reflected signal if the corresponding amplitude threshold is adjusted.

The Radar Configuration Tool (RCT) lets you view a waveform plot to analyze the measurement signal. The plot shows the signal and the thresholds used for the different amplitude peaks. By adjusting amplitude threshold T3 it is possible to detect even weak interface signals.

Guidelines for amplitude threshold settings:

•The amplitude threshold T3 should be approximately 50 % of the interface signal amplitude.

•Threshold T3 should not be less than 3.

•If possible, T3 should be higher than T2.

You can use the RCT software or a HART 275 Communicator to change the amplitude thresholds. For the HART Communicator use the HART command [1, 4, 6, 2]. See also “Amplitude Threshold Settings” on page 6-13.

RCT lets you view a plot of the measurement signal along with the current thresholds:

1.From the 9LHZ menu choose the 3ORWWLQJ option, or double-click the Plotting icon in the Advanced section of the RCT Project Bar.

2.Click the Read button .

Figure 6-4. Waveform plot indicating that the amplitude threshold for the interface peak is too high.

3.To adjust the $PSOLWXGH￿7KUHVKROGV open the Advanced section in the RCT Project Bar and choose Device Commands>Details>Set Nominal Thresholds.

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