Emerson Daniel 3415

4.2.3 Batch cycle processing
Batch update period
Calculation updates performed by the meter, for deriving volume and velocity, are based
on batches of data samples collected from sequences of transducer firings. The batch
update period is dependent upon the user specified batch update period
(SpecBatchUpdtPeriod)and the stack size (StackSize) as shown in Table 4-1. The Standard
batch update period is the default. The actual batch update period is readable via the
BatchUpdatePeriod data point.
Actual meter update periodTable 4-1:
Stack size
1 (None) 2 4 8 16
SpecBatchUpdtPeriod Rapid
(250 ms)
0.25 sec N/A N/A N/A N/A
Standard
(1000 ms)
1 sec 1 sec 1.5 sec 3 sec 5 sec
Emission rates
The emission rate is the period between firing two different transducers. The stacked
emission rate is the period between consecutive firings of a single transducer when
stacking is used (i.e., the stack size is not set to None).
The actual emission rates used (readable via the EmRateActual and StackEmRateActual
data points) are functions of the desired emission rates, meter type, firing sequence, stack
size, and pipe diameter.
The user specifies the desired emission rates via the EmRateDesired and
StackEmRateDesired data points. If a desired emission rate is set to zero, the meter uses
the fastest possible emission rate which can be as short as is 2 milliseconds. Otherwise, the
meter uses the fastest possible emission rate that is not less than the desired value. We
recommend setting the Filter to the OFF position.
The Signal Analyzer (Meter|Signal Analyzer) is used to configure the EmRateDesired and
StackEm-RateDesired. These values are set to zero to achieve the most transducer firings
per batch update.
4.2.4
Smoothing
The Daniel 3410 Series Gas Ultrasonic Flow Meter applies a method for smoothing the
output (particularly the frequency output) by averaging times collected from past batch
periods with new times for the current batch period.
Smoothing can be applied in the following increments: 0 (i.e., smoothing is disabled), 20,
40, 60, or 80%.
Measurement
Operations manual 19