JP2013122399A - Transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmitter capable of controlling a gate time of a frequency conversion circuit to an optimal value by monitoring a fluctuation in a physical amount measurement value.SOLUTION: The transmitter provided with a vibration type sensor for outputting a vibration signal associated with a physical amount of a process, a frequency conversion circuit for sampling the vibration signal with a prescribed gate time to convert the vibration signal into a frequency signal, and a physical amount operation circuit for inputting the converted frequency signal and calculating and outputting the physical amount, includes gate time operation means for monitoring a variation of an output of the physical amount operation circuit and adjusting the gate time to an optimal value.

Description

  The present invention includes a vibration sensor that outputs a vibration signal related to a physical quantity of a process, a frequency conversion circuit that samples the vibration signal at a predetermined gate time and converts it into a frequency signal, and inputs the converted frequency signal. The present invention relates to a transmitter including a physical quantity calculation circuit that calculates and outputs the physical quantity.

  A vibration sensor that outputs a vibration signal related to the process physical quantity of differential pressure or pressure, a frequency conversion circuit that samples the vibration signal at a predetermined gate time and converts it into a frequency signal, and a difference obtained by inputting the converted frequency signal Details of a transmitter including a pressure or an arithmetic circuit that calculates and outputs pressure are disclosed in non-patent literature.

  FIG. 4 is a functional block diagram showing a configuration example of a conventional transmitter. The vibration type sensor 10 inputs a process physical quantity P of differential pressure or pressure, and inputs a vibration signal ei related to the physical quantity to the frequency conversion circuit 20.

  The frequency conversion circuit 20 samples the vibration signal ei at a predetermined gate time T0, converts it into a frequency signal fi, and inputs it to the physical quantity calculation means 30. The physical quantity calculating means 30 calculates an analog value or digital value output signal Ep proportional to the physical quantity P based on the relational expression between the physical quantity P and the frequency fi, and externally outputs it as a measured value of the physical quantity. The gate time T0 of the frequency conversion circuit 20 can be fixed by the device or set by the user.

Yokogawa Technical Report Vol.48 No.1 (2004)
New differential pressure / pressure transmitter DPharp EJX series

  In an application where the physical quantity P is not stable and the oscillation is large, the value of the output signal Ep fluctuates. In this case, there is a method of increasing the gate time T0 of the frequency conversion circuit 20 and stabilizing it.

  However, this gate time T0 needs to be fixed by the device or set by the user. When the magnitude of the swing changes with time, the user needs to readjust and reset each time. The man-hour will increase. In addition, it cannot be adjusted when the device is fixed.

  An object of the present invention is to realize a transmitter that can monitor fluctuations in physical quantity measurement values and control the gate time of a frequency conversion circuit to an optimum value.

In order to achieve such a subject, the present invention has the following configuration.
(1) A vibration type sensor that outputs a vibration signal related to a physical quantity of a process, a frequency conversion circuit that samples the vibration signal at a predetermined gate time and converts it into a frequency signal, and inputs the converted frequency signal. In a transmitter comprising a physical quantity calculation circuit that calculates and outputs a physical quantity
A transmitter comprising: a fluctuation suppressing means for monitoring a fluctuation value of an output of the physical quantity arithmetic circuit and adjusting the gate time to an optimum value.

(2) The transmitter according to (1), wherein the fluctuation suppressing unit monitors a fluctuation value of an output of the physical quantity calculation circuit.

(3) The transmitter according to (1), wherein the fluctuation suppressing unit monitors a frequency value of an output of the physical quantity calculation circuit.

(4) The transmitter according to any one of (1) to (3), wherein the fluctuation suppressing unit includes a switch unit that selectively gives an output of the physical quantity arithmetic circuit.

(5) The transmitter according to any one of (1) to (4), further comprising alarm means for notifying the output of the fluctuation suppressing means to the outside.

(6) The transmitter according to any one of (1) to (5), wherein the vibration sensor is a vibration differential pressure sensor or a vibration pressure sensor.

  According to the present invention, when the measured value of the physical quantity fluctuates or the fluctuation state changes with time, the optimum sampling gate time is automatically determined from the fluctuation value of the measurement value or the vibration frequency. By seeking and adjusting, it is possible to reduce the user's readjustment man-hours.

It is a functional block diagram which shows one Example of the transmitter to which this invention is applied. It is a wave form diagram which shows the example of a fluctuation | variation of the output signal of a physical quantity arithmetic circuit. It is a functional block diagram which shows the other Example of the transmitter to which this invention is applied. It is a functional block diagram which shows the structural example of the conventional transmitter.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a functional block diagram showing an embodiment of a transmitter to which the present invention is applied. The same elements as those in the conventional configuration described with reference to FIG.

  The characteristic part of the present invention added to the conventional configuration shown in FIG. 4 includes a fluctuation suppression means 100 that receives the output signal Ep of the physical quantity calculation circuit 30 and monitors the fluctuation of the measured value, and a control signal M from the fluctuation suppression means 100. Thus, the gate time setting means 200 for setting the gate time Ts of the frequency conversion circuit 20 is provided.

  The fluctuation suppressing means 100 calculates the magnitude of the fluctuation of the output signal Ep of the physical quantity calculation circuit 30, and determines the optimum gate time according to the magnitude. The calculated gate time is notified to the gate time setting means 200 as the control signal M, and the frequency conversion circuit 20 performs sampling at the optimum gate time Ts. This is repeated at regular intervals.

  FIG. 2 is a waveform diagram showing a variation example of the output signal Ep of the physical quantity calculation circuit. In the section a, since the swing is small, the gate time is reduced. In the interval b, since the swing is large, the gate time is increased. In the section c, since the swing is reduced again, the gate time is reduced.

  In the present invention, this gate time changing operation is automatically executed. For simplification, the magnitude of the swing is shown only in two stages, but the magnitude of the swing is identified in multiple stages, and the gate time corresponding to each is calculated and used as the actual gate time.

  If the gate time remains constant, the measured value of the physical quantity will fluctuate greatly in the section b. However, according to the present invention, the swing amplitude is set within the allowable range shown in the section a or the section b by the automatic operation of the gate time. It can be converged.

  In the description of FIG. 1 and FIG. 2, the fluctuation suppressing unit 100 calculates the optimal sampling gate time based on the magnitude of the fluctuation, but the optimal value based on the frequency of the output signal Ep of the physical quantity calculation circuit 30. The sampling gate time may be calculated. In this case, the control signal M is output to increase the gate time when the frequency is high, and to decrease the gate time when the frequency is low.

  When it is determined that the sampling time is not appropriate as a result of the fluctuation of the output signal Ep or the frequency monitoring by the fluctuation suppressing means 100, the alarm signal AL may be notified to the user by the alarm means 300 to which the control signal M is input. it can. As a result, the user can reset the sampling gate time at an appropriate timing.

  FIG. 3 is a functional block diagram showing another embodiment of a transmitter to which the present invention is applied. An element added to the configuration of FIG. 1 is a configuration in which a switch unit 400 that can be opened and closed by a user is provided between the physical quantity calculation circuit 30 and the fluctuation suppressing unit 100.

  In the embodiment of FIG. 1, the sampling gate time is automatically and periodically changed. However, by adding the switch means 400, the fluctuation value or frequency of the output signal Ep is measured only when the user permits it. The sampling gate time can be optimized. The switch means 400 may be operated so as to be automatically turned off after a predetermined time after the on operation.

  In the embodiments described above, the differential pressure / pressure transmitter disclosed in the non-patent literature is exemplified as the transmitter that employs the vibration sensor, but the present invention is not limited to this, and the Coriolis type The present invention can be generally applied to a transmitter having a vibration sensor that outputs a vibration signal related to a process physical quantity, such as a mass flow meter.

DESCRIPTION OF SYMBOLS 10 Vibration type sensor 20 Frequency conversion circuit 30 Physical quantity calculation circuit 100 Fluctuation suppression means 200 Gate time setting means 300 Alarm means 400 Switch means

Claims (6)

A vibration sensor that outputs a vibration signal related to a physical quantity of a process, a frequency conversion circuit that samples the vibration signal at a predetermined gate time and converts it into a frequency signal, and inputs the converted frequency signal to calculate the physical quantity And a physical quantity arithmetic circuit that outputs the
A transmitter comprising: a fluctuation suppressing means for monitoring a fluctuation value of an output of the physical quantity arithmetic circuit and controlling the gate time to an optimum value.   The transmitter according to claim 1, wherein the fluctuation suppressing unit monitors a fluctuation value of an output of the physical quantity calculation circuit.   The transmitter according to claim 1, wherein the fluctuation suppressing unit monitors a frequency value of an output of the physical quantity calculation circuit.   4. The transmitter according to claim 1, further comprising switch means for selectively giving the output of the physical quantity calculation circuit to the fluctuation suppressing means.   The transmitter according to any one of claims 1 to 4, further comprising an alarm means for notifying an output of the fluctuation suppressing means to the outside.   The transmitter according to any one of claims 1 to 5, wherein the vibration sensor is a vibration differential pressure sensor or a vibration pressure sensor.

Images