Micro Motion RFT9709 Manual de instrucciones descargar pdf (Pagina 126)

112

Using ProLink

Software with Micro Motion

Transmitters

Configure Menu: Transmitter Outputs

continued

Milliamp outputs

K-factor

The K-factor enables the user to read the frequency or number of pulses

that is proportional to a unit of flow.

As described above, scaling the frequency/pulse output requires entry of

frequency and rate. The output is scaled so the frequency or number of

pulses per unit of time is always proportional to the flow rate, regardless

of the process variable assigned to the output.

10.3 Milliamp outputs

The RFT9739 has primary and secondary milliamp outputs that

independently produce a 0-20 or 4-20 mA current. The IFT9701,

IFT9703, RFT9712, and RFT9729 have a single 4-20 mA output.

Milliamp outputs can go to controllers, PLCs, or recording devices.

• Milliamp output variables require a lower range value and an upper

range value.

• Each milliamp output can have a flow cutoff if mass flow or volume

flow is the output variable.

• Milliamp outputs from the RFT9739 can have added damping if the

output variable is mass flow, volume flow, density, or temperature.

Milliamp output variables

For an RFT9739, RFT9712, or RFT9729, use the drop-down list boxes

under Milliamp, Milliamp 1, and Milliamp 2 to select variables indicated

by milliamp outputs.

The RFT9739 0-20 or 4-20 mA outputs can independently indicate mass

flow, volume flow, density, temperature, differential pressure, viscosity,

event 1 status or event 2 status.

• To select variables indicated by RFT9739 mA outputs, use the

drop-down list boxes under Milliamp 1 and Milliamp 2

• To configure the RFT9739 milliamp outputs spans, see the

transmitter instruction manual.

Example:

Given:

The RFT9739 frequency/pulse output goes to a totalizer with a

specified pulse width requirement of 50 milliseconds. The maximum

frequency input to the totalizer is 10 pulses per second.

Problem:

The RFT9739 maximum frequency output exceeds the

totalizer specifications.

Solution:

Since 50 milliseconds equals 0.05 seconds (50 * 0.001 =

0.05), the totalizer pulse width requirement is 0.05. Enter a value of

0.050 into the Max Pulse text box in the Configure Outputs dialog box.

For frequency less than 10 Hz, the frequency output will have a

50 millisecond ON state. For frequency higher than 10 Hz, the

frequency output will be a square wave with a 50% duty cycle.

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Micro Motion RFT9709 Manual de instrucciones Pagina 126

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