Emerson IFT9701 Manuel D’Utilisation
38
Model IFT9701 Transmitter Instruction Manual
Configuration with a HART Communicator
continued
7. At the detailed setup menu, choose 2 (configure field device variables).
8. At the configure field device variables menu, choose 3 (temperature unit).
6.2.3
Flow cutoff
In some sensor installations, noise caused by mechanical sources, such as valves and motors, can
affect flowmeter output signals. The flow cutoff filters out noise by defining the measured value
below which the milliamp output indicates zero flow.
affect flowmeter output signals. The flow cutoff filters out noise by defining the measured value
below which the milliamp output indicates zero flow.
The flow cutoff is the lowest flow rate at which the meter produces a nonzero output signal. If flow
drops below the cutoff:
drops below the cutoff:
•
The pulse output goes to 0 Hz.
•
The internal totalizer stops counting.
•
The meter indicates zero flow during polling from a host controller.
A default flow cutoff is entered into the flowmeter at the factory. This number can be adjusted to
achieve the filter effect described above.
achieve the filter effect described above.
To adjust the flow cutoff, use the menu below and follow these steps:
1. At the online menu, choose 4 (detailed setup).
2. At the detailed setup menu, choose 2 (configure field device variables).
3. At the configure field device variables menu, choose 1 (flow).
4. At the flow menu, choose 2 (flow cutoff).
5. Enter the desired flow cutoff value.
6. Press F2 (send) to send the flow cutoff to the flowmeter memory.
6.2.4
Damping
Internal damping filters out noise or the effects of rapid changes in the variable without affecting
measurement accuracy.
measurement accuracy.
The damping value is the filter coefficient that approximates the time required for the output to
achieve 63% of its new value in response to a step change at the input. The actual time depends on
many factors, including sensor type and density of the process fluid. The meter rounds down the
chosen damping value to the nearest programmed filter coefficient. Programmed filter coefficients, in
seconds, are:
achieve 63% of its new value in response to a step change at the input. The actual time depends on
many factors, including sensor type and density of the process fluid. The meter rounds down the
chosen damping value to the nearest programmed filter coefficient. Programmed filter coefficients, in
seconds, are:
1 Process variables
2 Diag/service
3 Basic setup
4 DETAILED SETUP
5 Review
2 Diag/service
3 Basic setup
4 DETAILED SETUP
5 Review
1 Charize sensor
2 CONFIG FLD
2 CONFIG FLD
DEV VAR
3 Config outputs
4 Device
4 Device
1 Flo unit
2 FLO CUTOFF
3 Flo direction
4 Flow damping
2 FLO CUTOFF
3 Flo direction
4 Flow damping
1 FLOW
2 Density
3 Temp unit
2 Density
3 Temp unit
0.1
0.2
0.4
0.8
1.6
3.2
6.4
12.8