Operation Manual

8-4
IM 1F5B2-01E
8.2.3 Trigger Level Adjustment (TLA) (Parameter H10)
■ TLA helps suppress the effects of external noise.
■ Parameter H10 (TLA) is adjusted to 0 as the default when ULTRA YEWFLO is
shipped from the factory.
■ ULTRA YEWFLO in principle is hardly affected by mechanical vibration. Make a
trigger level adjustment, however, if external noise is an issue or if ULTRA
YEWFLO gives a reading larger than the true value while the flowrate is zero.
■ Setting parameter H10 at a larger value (for example, a value from 0 to 2) heightens
the trigger level. This strategy will help reduce the effect of noise.
IMPORTANT
•Care must be taken when making a trigger level adjustment. If you set the parameter
for TLA at a value larger than necessary, the measurable lower limit of the flow
velocity rises to an unacceptable level, possibly impeding your measurement.
Before TLA Before TLA
High trigger level
Low trigger level
Waveform observed
across TP2 and COM
Waveform observed
across P and COM
Waveform observed across
TP2 and COM
Waveform observed across
P and COM
After TLA
High trigger level
Low trigger level
Waveform observed
across TP2 and COM
Waveform observed
across P and COM
Waveform observed
across TP2 and COM
Waveform observed
across P and COM
After TLA
Figure 8.2-3 Trigger Level Adjustment (at Lower Flowrates)
8.2.4 Loop Tests (Parameters F10 and F20)
• You can have ULTRA YEWFLO provide either a 4-20 mA DC output of 0.0% to
110.0% (parameter F10: SET % MODE) or a pulse output of 0 to 6,000 Hz (param-
eter F20: SET F MODE) for your loop tests.