Справочник Пользователя для Emerson Process Management 3420

June 2013

3-9000-743 Rev S

The Daniel Mark III Ultrasonic Gas Flow Meter meter introduces a method for smoothing the 
output (particularly the frequency output) by averaging samples (i.e., waveforms) collected 
from past batch periods with new samples for the current batch period.

Smoothing can be applied in the following increments: 0 (i.e., smoothing is disabled), 20, 40, 
60, or 80%.

For example, setting Smoothing to 20% means that of the samples used for the current update, 
20% will be from previously collected samples and 80% will be from the newly collected 
samples. Thus, if 8 new samples are collected, then those 8 samples along with the last 2 
previous samples would be used together for the current update period calculations.

Meters are configured by default for Smoothing of 0% (only new samples are used for the 
current update period).

6.1.4

Acquisition mode

The Mark III meter has two modes of normal operation: Acquisition and Measurement. The 
Acquisition mode is used to acquire the ultrasonic signals. This mode is entered upon powering 
up the meter. Once the ultrasonic signals are acquired, the Measurement mode is entered and 
the flow velocity is measured. The meter remains in the Measurement mode as long as at least 
one chord is operational. If all chords fail while in the Measurement mode, then the Acquisition 
mode is re-entered.

The meter operation mode is indicated by the 

IsAcqMode data point. When TRUE, the meter is 

in the Acquisition mode; when FALSE, the meter is in the Measurement mode.

The Acquisition mode uses the chords' “L” dimensions (

Laird as appropriate to the meter type) 

and the specified minimum and maximum sound velocities (

SSMin and SSMax) to determine 

the signal search range.