JP2006309693A - Multivariate transmitter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the following problems: a multivariate transmitter has only one variate capable of being simultaneously outputted in current output; and a lot of cost is required for output of the multivariate because digital output of a field bus or the like has to be performed so as to output a multivariate to require a change of the whole system including a reception instrument. <P>SOLUTION: In this multivariate transmitter, a plurality of sensor signals corresponding to a plurality of physical quantities of a process are inputted, the sensor signals are calculated by an arithmetic processing means, and arithmetic output of the arithmetic processing means is transmitted to the outside as the current output. The multivariate transmitter has a multiplexer sequentially changing over and outputting the arithmetic output of a plurality of destinations. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is a multivariate transmission in which a plurality of sensor signals corresponding to a plurality of physical quantities of a process are input, these sensor signals are calculated by an arithmetic processing means, and the arithmetic output of the arithmetic processing means is transmitted to the outside as a current output. More particularly, the present invention relates to a multivariate transmitter capable of measuring a plurality of physical quantities at low cost and transmitting them to the outside.

  FIG. 4 is a block diagram showing the configuration of a conventional multivariate transmitter. In this case, it is shown as a configuration of a mass flow meter using a general-purpose differential pressure transmitter used as a field device for process control.

In this mass flow meter, a differential pressure, which is a physical quantity directly to be measured, is measured by a differential pressure sensor, and a pressure and a temperature, which are physical quantities for mass flow calculation, are measured by a pressure sensor and a temperature sensor. The mass flow rate, which is the target physical quantity, is indirectly measured by the arithmetic processing using the variable.

Hereinafter, a mass flow meter as a multivariate transmitter using three variables will be specifically described with reference to FIG. The measurement signals of the differential pressure sensor 1, the pressure sensor 2 and the temperature sensor 3 are converted into digital values ed, ep and et by the A / D converters 4, 5, and 6, respectively, and are processed by a microprocessor (MPU). Input to means 7.

The arithmetic processing means 7 stores the digital values ed, ep and et inputted from each sensor in the memory 8 and calculates the mass flow rate using them, and outputs a digital mass flow rate signal eq.

The digital mass flow signal eq is converted into an analog voltage value by the D / A converter 9 and output to the output means 10. The D / A converter 9 converts this voltage value into a current output I such as 4-20 mA via the output means 10 and supplies it to a series circuit of the receiving instrument 11 and the DC power supply 12.

In this case, each variable of differential pressure, pressure, and temperature is input to the differential pressure transmitter, and the mass flow is indirectly calculated and output as one. However, in a specific differential pressure transmitter, The differential pressure value and the pressure value can be output. In practice, either the differential pressure value or the pressure value can be switched and output for each variable.

  As a prior art, in Patent Document 1 below, a plurality of sensor signals corresponding to a plurality of physical quantities of a process are input, these sensor signals are calculated by an arithmetic processing means, and an arithmetic output of the arithmetic processing means is externally output. Describes a multivariate transmitter that transmits as a current output.

JP 2004-85288 A

  However, such a multivariate transmitter can output only one variable at the same time at a current output of 4-20 mA or the like. In order to output other variables, there is only a digital output such as a field bus, and the entire system including the receiving instrument needs to be changed.

  An object of the present invention is to provide a multivariate transmitter capable of measuring and transmitting multivariate at a low cost while maintaining a conventional current output transmission system such as 4-20 mA. .

The present invention which achieves such an object is as follows.
(1) A multivariate transmitter that inputs a plurality of sensor signals corresponding to a plurality of physical quantities of a process, calculates these sensor signals by an arithmetic processing means, and transmits the arithmetic output of the arithmetic processing means to the outside as a current output A multivariate transmitter comprising a multiplexer that sequentially switches and outputs a plurality of the arithmetic outputs.
(2) The calculation processing means determines an output area for the current output corresponding to each sensor signal, and switches the physical quantity to the output area for output. Multivariate transmitter.
(3) The arithmetic processing means switches a plurality of the sensor signals and periodically outputs them, generates a timing pulse to the pulse generation unit in units of this cycle, and generates a current pulse corresponding to the timing pulse. The multivariate transmitter according to (1), characterized in that the current output can be output.
(4) In a multivariate transmitter that inputs a plurality of sensor signals corresponding to a plurality of physical quantities of a process, calculates the sensor signal by an arithmetic processing means, and transmits the arithmetic output of the arithmetic processing means to the outside as a current output A multivariate transmitter comprising: a memory that simultaneously stores information of the plurality of sensor signals; and a multiplexer that sequentially switches and outputs the information stored in the memory.

The present invention has the following features.
(A) A multivariate transmitter for inputting a plurality of sensor signals corresponding to a plurality of physical quantities of a process, calculating these sensor signals with an arithmetic processing means, and transmitting the arithmetic output of the arithmetic processing means to the outside as a current output A multivariate transmitter comprising a multiplexer that sequentially switches and outputs a plurality of the arithmetic outputs.
(B) The multivariate transmitter according to (A), wherein the arithmetic processing means determines an output area for the current output corresponding to each sensor signal, and switches the physical quantity to the output area for output.
(C) The arithmetic processing means generates a timing pulse at a predetermined cycle for the pulse generator, and can output a current pulse corresponding to the timing pulse in the current output. Variable quantity transmitter.
(D) The arithmetic processing means switches a plurality of the sensor signals and periodically outputs them, generates a timing pulse to the pulse generation unit in units of this cycle, and generates a current pulse corresponding to the timing pulse. The multivariate transmitter according to (A), wherein the output can be included in the current output.

  Conventionally, when performing multivariate measurement in a multivariate transmitter, there was no choice but to rely on digital output by a fieldbus or the like, but in the present invention, each variable is output periodically (cyclically) even in a conventional current transmission system. Thus, there is an advantage that inexpensive multivariate measurement can be realized.

  Moreover, even if an existing current transmission (4-20 mA) instrumentation system is used in a factory or a plant, the installation of the multivariate transmitter of the present invention having a periodic (cyclic) output function and the change or grade of the receiving instrument Multivariate measurement is possible with the degree of improvement, which is highly cost-effective.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a multivariate transmitter according to the present invention. In FIG. 1, measurement signals Sd, Sp, or St of the differential pressure sensor 21, the static pressure sensor 22, and the temperature sensor 23 are input to the arithmetic processing unit 24.

  The arithmetic processing unit 24 periodically (cyclically) stores the measurement signal Sd, Sp or St input from each sensor in accordance with a predetermined program according to an output range of a current output Io described later. The calculation outputs Ad, Ap, and At corresponding to the measurement signals Sd, Sp, or St are output to the multiplexer 26 by performing calculations such as span adjustment, offset adjustment, and the like.

  The arithmetic processing means 24 outputs a timing pulse TP to the pulse generator 27 and outputs a synchronization signal SS for synchronizing with a receiving instrument 27 described later from the pulse generator 27 to the multiplexer 26. Let

  The multiplexer 26 outputs the synchronization signal SS to the D / A converter 28 together with the operation outputs Ad, Ap, and At. The D / A converter 28 converts these into analog signals and outputs them to the output means 29.

  The output means 29 outputs the differential pressure signal corresponding to the calculation outputs Ad, Ap and At, the static pressure signal, the temperature signal, and the current output Io such as 4-20 mA corresponding to the synchronization pulse SP related to the synchronization signal SS. And is supplied to a series circuit of the receiving instrument 27 and the DC power supply 30.

  Here, the arithmetic processing means 24, the multiplexer 26, the pulse generator 27 and the like are built in a CPU (Central Processing Unit) 31, and the CPU 31, the D / A converter 28, the memory 25, the output means 29 and the like are multivariate. A differential pressure transmitter 32 as a transmitter is configured.

  It should be noted that, if the multiplexer 26, the pulse generator 27, etc. are built in the CPU 31, there are advantages in reducing the number of parts and the cost, but these functions are not necessarily built in the CPU 31 if they have these functions.

  Next, the operation of the differential pressure transmitter 32 as the multivariate transmitter shown in FIG. 1 will be described with reference to FIG. FIG. 2A shows time (min) on the horizontal axis and differential pressure (%), static pressure (%), and temperature (° C.) on the vertical axis, and the differential pressure, static pressure, An example in which the temperature changes is shown.

  In FIG. 2B, the horizontal axis represents time, the left vertical axis represents differential pressure (%), static pressure (%), temperature (° C.), and the right vertical axis represents 4-20 mA current output Io. The current output Io is output by switching the differential pressure, static pressure, and temperature over time.

  Furthermore, FIG. 2 (B) illustrates the state in which the differential pressure, static pressure, and temperature are switched for only 20 to 30 minutes after the start of measurement (0 minutes) in FIG. 2 (A). is there. In this case, the 4-20 mA current output Io is switched every 20 seconds between differential pressure (DP), static pressure (SP), and temperature (T).

  Here, since three variables are switched every 20 seconds, each variable measures a change (21, 22,..., 30) every minute. That is, while measuring the differential pressure, static pressure, and temperature in one minute, these are set as one cycle, and this is output repeatedly.

  Next, a description will be given of a configuration in which the periodically output signal is distributed for each variable and transmitted as a current output.

  First, there is a case in which the output ranges of the variables are set so as not to overlap. That is, the output region of the current output Io (4-20 mA) is divided, and for example, the differential pressure is 4 mA to 10 mA, the static pressure is 10 mA to 15 mA, the temperature is 15 mA to 20 mA, etc., and the current output Io is If it is 12 mA, static pressure data is shown, and the static pressure is determined to be (12 mA-10 mA) / (15 mA-10 mA) = 40% static pressure.

  That is, specifically, offset adjustment and span adjustment are performed in advance by the arithmetic processing unit 24 corresponding to the respective sensor outputs of the differential pressure sensor 21, the static pressure sensor 22, and the temperature sensor 23 so as to become like this. It is a configuration.

  By doing so, the receiving instrument 27 can distribute the variables. In this case, when the temperature accuracy may be low, the temperature output range is set to be small, and the differential pressure output range is set to be wide.

  Secondly, the differential pressure transmitter 32 and the receiving instrument 27 have the same period. The arithmetic processing means 24 causes the pulse generator 28 to generate a timing pulse TP at a predetermined cycle, and includes the current pulse Ip corresponding to the synchronization pulse SP related to the timing pulse TP in the current output Io (4-20 mA). The receiving instrument 27 is configured to match the period with the current pulse Ip as a reference so that it can be output.

  In this case, the current pulse Ip is set to once every fixed time, and the period is periodically matched. In the case of FIG. 2, for example, the current pulse Ip is input at the start of measurement (0 minutes), and then the current pulse Ip is input at regular time intervals and the current output Io is transmitted. Each variable is assigned based on the passage of time after reception.

  For example, the current pulse Ip is set to 4 mA or less, or 20 mA or more. On the receiving instrument 27 side, when the current pulse is set to 4 mA or less, the first falling edge is set. Call. This is because the next variable of the current pulse Ip is an error output or the like, and may output other than 4-20 mA.

  If the receiving instrument 27 side can correctly recognize even the current pulse Ip, the distribution of each variable can be performed based on the passage of time after receiving the current pulse.

  Thirdly, the arithmetic processing means 24 switches and outputs a plurality of sensor signals periodically, and generates a timing pulse TP for the pulse generator in units of this period, and a synchronization pulse related to the timing pulse TP. The current pulse Ip corresponding to SP is included in the current output Io (4-20 mA) and output.

  This is not the case where the current pulse Ip is simply transmitted every predetermined period as in the second case, but the current pulse Ip is present every time for each unit with the differential pressure, static pressure and temperature as one unit. It is a configuration. That is, current pulse Ip → differential pressure → static pressure → temperature → current pulse Ip...

  Since the periods of the differential pressure transmitter 32 and the receiving instrument 27 are gradually shifted due to instrumental differences, the period may not coincide with the passage of time in the second case, but the current pulse Ip every time in the third case Since the period is inserted, there is an advantage that the cycle does not shift.

  However, the current pulse Ip is wasted time for measuring each variable. For example, if the current pulse Ip is 2 seconds and each variable is output for 2 seconds, one cycle at the time of trivariate measurement is 8 seconds. If the current pulse Ip is not input every time, one cycle is 6 seconds, so that the cycle can be shortened. These second and third configurations are not preferred either, and are selected according to the usage method and needs.

  Further, in the above-described embodiment, for example, when calculating the mass flow rate, it is necessary to simultaneously measure each measurement variable. Specifically, in a multivariable switching type transmitter, when the output is switched in the order of differential pressure, static pressure, and temperature, the timing of measurement of each variable is different. Therefore, when the measured flow rate changes during the variable switching output, the correct mass flow rate cannot be obtained even if the flow rate is calculated from each variable.

  Therefore, in such a case, the configuration is such that all variables are measured at a certain same time (every period), calculation processing is executed, temporarily stored in a memory (storage means), and then output with a time difference (see FIG. (Not shown) to be prepared.

  According to such a configuration, a correct mass flow rate can be obtained together with the above-described effects. For example, the measurement (output) of each variable is set to 2 seconds. First, while the first variable (differential pressure) is output for 2 seconds, other variables (static pressure and temperature) are stored in the memory. Next, the second variable (static pressure) is output from the memory for 2 seconds. Finally, the third variable (temperature) is output from the memory for 2 seconds. That is, in this method, three variables are output every 6 seconds simultaneously for 2 seconds.

  In addition to the above-described embodiments, the output time and measurement period of each variable can be arbitrarily set by the user, and the measurement of each variable in real time, which is not stored in the memory, can be switched with a predetermined setting. The configuration is made possible. In such a configuration, the degree of freedom of measurement is widened in addition to the above-described effects.

  Hereinafter, the present invention will be described in detail with reference to FIG. FIG. 3 is a timing chart showing the operation of one embodiment of the present invention (the embodiment of FIG. 1).

  The feature of the embodiment of FIG. 3 resides in a memory 25 that simultaneously stores information of a plurality of sensor signals, and a multiplexer 26 that sequentially switches and outputs the information stored in the memory 25.

  The memory 25 stores, for example, the calculation output of the calculation output means 24, that is, the calculation output Md related to the differential pressure sensor 21, the calculation output Ms related to the static pressure sensor, and the calculation output Mt related to the temperature sensor at the same time.

  Further, for example, the multiplexer 26 first outputs the information Od related to the differential pressure sensor 21 stored in the memory 25, then outputs the information Os related to the static pressure sensor stored in the memory 25, and finally The information Ot related to the temperature sensor stored in the memory 25 is output.

  Specifically, the multiplexer 26 first outputs information Od related to the differential pressure sensor 21 for 2 seconds, next outputs information Os related to the static pressure sensor for 2 seconds, and finally outputs information Ot related to the temperature sensor. Is output for 2 seconds. Thus, the multiplexer 26 repeatedly outputs the three variables every 6 seconds.

  As described above, in the embodiment according to FIG. 3, the measurement timing of each variable becomes the same, and an accurate mass flow rate can be obtained easily.

  An embodiment different from the above-described embodiment will be described.

  The memory 25 simultaneously stores, for example, information from the differential pressure sensor 21, information from the static pressure sensor 22, and information from the temperature sensor 23.

  Further, for example, the multiplexer 26 first outputs the calculation output Od of the calculation processing means 24 based on the information related to the differential pressure sensor 21 stored in the memory 25, and then outputs the calculation output Od to the static pressure sensor stored in the memory 25. The calculation output Os of the calculation processing unit 24 based on the information is output, and finally the calculation output Ot of the calculation processing unit 24 based on the information related to the temperature sensor stored in the memory 25 is output.

  Specifically, the multiplexer 26 first outputs the calculation output Od of the calculation processing unit 24 based on the information related to the differential pressure sensor 21 for 2 seconds, and then the calculation processing unit 24 based on the information related to the static pressure sensor. The calculation output Os is output for 2 seconds, and finally the calculation output Ot of the calculation processing means 24 based on the information related to the temperature sensor is output for 2 seconds. Thus, the multiplexer 26 repeatedly outputs the three variables every 6 seconds.

  In this case, the configuration is substantially the same as described above, and an accurate mass flow rate can be easily obtained.

  As described above, the present invention is not limited to the above-described embodiments, and includes many changes and modifications without departing from the essence thereof.

It is a block diagram which shows one Example of this invention. It is explanatory drawing for demonstrating operation | movement of one Example of this invention. It is a timing chart which shows operation | movement of one Example of this invention. It is a block diagram which shows the structure of the conventional multivariate transmitter.

Explanation of symbols

1, 21 Differential pressure sensor 2 Pressure sensor 22 Static pressure sensor 3, 23 Temperature sensor 4, 5, 6 A / D converter 7, 24 Arithmetic processing means 8, 25 Memory 9, 28 D / A converter 10, 29 Output means 11 27 Receiving instrument 12, 30 DC power supply 26 Multiplexer 28 Pulse generator 31 CPU
32 Differential pressure transmitter TP Timing pulse SS Sync signal

Claims (4)

In a multivariate transmitter that inputs a plurality of sensor signals corresponding to a plurality of physical quantities of a process, calculates these sensor signals with an arithmetic processing means, and transmits the arithmetic output of the arithmetic processing means to the outside as a current output.
A multivariate transmitter comprising a multiplexer that sequentially switches and outputs a plurality of the arithmetic outputs. 2. The multivariate transmission according to claim 1, wherein the arithmetic processing unit determines an output area for the current output corresponding to each sensor signal, and switches and outputs the physical quantity to the output area. vessel. The arithmetic processing means switches a plurality of the sensor signals and periodically outputs them, generates a timing pulse to the pulse generation unit in units of this cycle, and outputs a current pulse corresponding to the timing pulse as the current output The multivariate transmitter according to claim 1, wherein the multivariable transmitter is configured to be capable of being output. In a multivariate transmitter that inputs a plurality of sensor signals corresponding to a plurality of physical quantities of a process, calculates the sensor signal by an arithmetic processing unit, and transmits the arithmetic output of the arithmetic processing unit to the outside as a current output.
A memory for simultaneously storing information of a plurality of the sensor signals;
A multivariate transmitter comprising: a multiplexer that sequentially switches and outputs information stored in the memory.

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