Command Modes; Digital Damping Control (Hot Key 1 And 2); Transit Time Adjustment (Hot Key 3); Zero Crossover Adjustment (Hot Key 4) - Siemens SITRANS FUG1010 IP65 NEMA 4X Instruction Manual

1010GCNFM-3C
Section 4

Command Modes

Although the FUG1010GCN signal processing algorithms are capable of accommodating a very wide
range of signal conditions, it may be desirable to override these default settings under extremely difficult
operating conditions. The following functions are available for this purpose:
Digital Damping Control: (Hot Key 1 and 2)
The FUG1010GCN permits user modification of the digital averaging used by the signal processing
routines. In general, the default damping values selected by FUG1010GCN will provide optimal perfor-
mance over a wide range of transit time applications. However, in extreme cases of unstable flow profile,
low signal levels or high aeration it may be necessary to override these default settings to permit uninter-
rupted and reliable flow measurement.
The FUG1010GCN Graph Screen includes the capability to access a set of command codes, which
enable a user to override a number of default setup parameters. The most important parameter is the
digital damping control, which can be accessed by pressing number <1> or <2> on the keypad while
in the graph screen mode.
Pressing the <1> key will cause [MinDamp #] to appear on the command line at the lower left-hand
corner of the screen. The number listed to the right of the command code represents the exponent in the
FUG1010GCN exponential averaging routine, where the larger the number the greater the digital aver-
aging. Pressing the <+> key will increase the damping value. Likewise, pressing the <-> key will de-
crease the damping value. To exit this mode, press the <0> key on the keypad.
Pressing the <2> key will bring up the [MaxDamp] command. The function of this parameter is similar to
the [MinDamp] command described above, however, the two parameters interact in the following man-
ner. The MinDamp value must not exceed the MaxDamp value, therefore increasing the MinDamp value
above the previous MaxDamp value will set both parameters to the same value. In most cases, it is
preferred that both damping parameters be set to the same value, however, in cases where rapid
response to changes in liquid sound velocity is required, the two values may be set differently. In this
situation the meter will use the MaxDamp value when sound velocity is stable, but then switch to a faster
damping value (limited by MinDamp) when a significant change in sound velocity is perceived. To exit
this mode, press the <0> key on the keypad.
Transit Time Adjustment: (Hot Key 3)
Observe the short vertical marker at the beginning of the receive signal in the Graph Screen above. This
line represents the position in time (Tn) where the FUG1010GCN flowmeter perceives the arrival of the
ultrasonic signal. There are actually two Tn markers, one for the upstream arrival time and one for the
downstream arrival time. For proper liquid sound velocity measurement these Tn markers should be
positioned near the beginning edge of the receive waveform envelope (as shown), however, in cases of
poor signal conditions it is possible for this measurement to be off by several receive waveform cycles.
To adjust the Tn mark position press the <3> key on the keypad to bring up the [TnSet] command.
Pressing the <+> or <-> keys will cause the Tn marker to move later or earlier, respectively. As you adjust
the Tn marker, both Tn and Vs (liquid sound velocity) will change accordingly. To exit this mode, press the
<0> key on the keypad.
Zero Crossover Adjustment: (Hot Key 4)
Observe the small "X" mark located on the zero crossing line near the middle of the receive signal in the
Graph Screen above. This "X" indicates the central crossover which the FUG1010GCN is using to meas-
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