JP2002175102A - Measurement terminal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make unnecessary such complicated circuit designing for every function and the increase of the device size, cost-up, and maintenance that may occur when various computing operations are carried out to an analogue measurement signal and the computing result is transmitted to a device in higher order via analogue transmission. SOLUTION: In an input/output circuit 1, respective measurement signals are converted into digital values to be inputted. In a digital computing part 2 and a data storage part 3, digital computing is carried out on each of the measurement signals converted into the digital values for every computing function by a software structure. The input/output circuit 1 converts the computing result into an analogue signal and outputs it to an analogue transmission passage. A program and setting data stored in the data storage part are downloaded from the outside for changing the computing function.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring terminal device for performing various functional calculations on various measurement signals and transmitting the calculation results to a higher-level device via an analog transmission line.

[0002]

2. Description of the Related Art A remote monitoring control system installed in a steel industry, an oil plant, or the like is provided with a large number of measuring instruments at each part of each control station to obtain measurement signals such as voltage, temperature, and pressure.
Each slave station installed at the control station converts these measurement signals into analog signals that match the transmission specifications, and then performs the required arithmetic processing to convert them to analog signals, which are transmitted to the master station via analog transmission lines. I am trying to do it.

Similarly, in a control system of a generator facility or a motor facility, a measurement circuit performs various arithmetic processing on a measurement signal of each part and transmits the signal to a control system body.

[0004] The transmission specification of the analog measurement signal is regulated such as, for example, 4 to 20 mA DC for the current type and 1 to 5 V DC for the voltage type. The arithmetic processing for the measurement signal
It performs addition and subtraction of a plurality of measurement signals, ratio calculation, integration, multiplication / division, square root calculation, temperature / pressure correction calculation, and the like.

In the measurement terminal device having the above-described arithmetic and conversion functions, since most of the measurement signals are obtained in analog quantities and the transmission signals are in analog quantities, hardware for each function using an operational amplifier circuit or a discrete electronic circuit is used. Is configured.

[0006]

A measuring terminal device such as a slave station of the above-mentioned remote monitoring control system newly newly designs an operational amplifier circuit and a discrete electronic circuit for each arithmetic function according to a difference in measurement signal input conditions and the like. There is a need. In addition, a measurement terminal device that collects and transmits a large number of measurement signals has a problem that the hardware configuration is complicated and the size is increased.

Further, the functions required of the measuring terminal device are different depending on the system, and even if the numerical specifications are slightly different, redesigning of the measuring terminal device is required. there were.

Further, in the hardware configuration, the operation tends to be unstable due to aging or the like, and a heavy burden is imposed on maintenance and inspection.

An object of the present invention is to provide a measuring terminal device which solves the above-mentioned problems.

[0010]

SUMMARY OF THE INVENTION A measuring terminal device according to the present invention converts various measured analog signals into digital quantities once, collects them, performs various calculations by digital calculation, and returns the calculation results to analog signals again. By transmitting the data to a higher-level device and realizing these calculation functions in a software configuration, the size of the device can be reduced. The calculation functions can be changed by externally changing (rewriting) a program. It eliminates the need for design for each function and features the following configuration.

[0011] A measurement terminal device that performs various functional calculations on various measurement signals that become analog signals and transmits the calculation results to a higher-level device via an analog transmission path. Input means for converting into a quantity, taking in the digital signal, computing means for performing a digital computation for each computation function with a software configuration for each measurement signal converted to the digital quantity, and converting the computation result into an analog signal and transmitting the analog signal Output means for outputting to a road.

Further, the program and the setting data are provided with means for externally downloading the program and the setting data to the data storage unit to change the arithmetic function.

[0013]

FIG. 1 is a block diagram of a measuring terminal device 10 according to an embodiment of the present invention. The measuring terminal device 10 has a microprocessor configuration for realizing a calculation function for each measurement signal by a software configuration.

The analog input / output circuit 1 switches and takes in analog measurement signals from various measuring instruments in a time-division manner, converts each measurement signal into a digital signal (A / D conversion), and transfers it to the memory of the digital operation unit 2. I do. The analog input / output circuit 1 converts the data into an analog signal (D / A conversion) when digital data, which is a calculation result from the digital calculation unit 2, is transferred from the digital calculation unit 2 to meet the signal specifications of the analog transmission line. Change and output.

In the analog input / output circuit 1 having such a function, for example, the input circuit is composed of a multiplexer, a sample hold circuit, and an A / D converter, and converts an input analog signal into digital data. The output circuit is
It is composed of a data buffer, a D / A converter, and an analog transmission circuit, and converts input digital data into an analog signal.

The digital operation unit 2 is bus-connected to a data storage unit 2 having a configuration including a rewritable semiconductor memory.
Using a program and setting data that are rewritably stored in the data storage unit 3, control of the input / output circuit 1 for synchronously capturing each measurement signal, execution of individual calculations for each measurement signal, and calculation results Control for sequentially transferring data to the input / output circuit 1 is performed.

The operation functions realized by the digital operation unit 2 and the data storage unit 3 are the same as those of the prior art, such as addition and subtraction of a plurality of measurement signals, ratio operation, integration, multiplication / division, square root operation, temperature / pressure correction operation, and the like. These are performed by executing an arithmetic program.

When data according to a predetermined communication protocol is required for data transmission to a master station or a control device main body which is a higher-level device, the function of the measuring terminal device 10 is also provided by a software configuration. .

According to the above configuration, each measurement signal that becomes an analog signal is temporarily converted into digital data by the input / output circuit 1, various functions are calculated based on the digital data, and the calculation result is returned to the analog signal to be converted to an analog signal. To the device.

As a result, the measuring terminal device 10 does not require a hardware circuit for each of the various required arithmetic functions, and the components can be simplified and the size thereof can be reduced. In addition, the arithmetic function to be used can be arbitrarily changed by a program written in the data storage unit 3, and new functions can be easily added. When the function required for the measurement terminal device is different or the numerical specification is different. In addition, the data can be rewritten, eliminating the need to redesign the measurement terminal device. further,
Operation is not unstable due to aging, etc., and maintenance is almost unnecessary.

FIG. 2 shows an example of the configuration of a measurement system in which a measurement terminal device is connected to a host computer at a higher level. At least one measurement terminal device 10 and host computer 1
1 is connected to the measurement terminal device 1 by an analog transmission line 12.
The various measurement signals input at 0 and the calculation results thereof are transmitted to the host computer 11 in accordance with the transmission specifications of the transmission line 12, and the host computer 11 converts the received analog signals into digital data and takes them in. Perform processing.

Conversely, when performing measurement control by the host computer 11, an analog control signal is transmitted from the host computer 11 to the input / output circuit 1 of the measurement terminal device 10 via the analog transmission line 12, and the control signal is transmitted. Based on this, the digital operation unit 2 executes measurement control.

Here, the measuring terminal device 10 is provided with a data communication connector 10B on the front panel 10A.
As shown in FIG. 1, the connector 10B is bus-connected to the digital operation unit 2 and the data storage unit 3 via the interface circuit 10C to rewrite programs and setting data in the data storage unit 3. Enables downloading.

The downloading of the information is performed by information communication from the personal computer 13 by connecting the portable personal computer 13 as a data logger with a connector via a signal cable 13A. The rewriting of the data storage unit 3 is performed by the personal computer 13
Is selected by selecting each arithmetic function from the setting screen and inputting necessary setting data values by key, and executing data communication.

The rewriting of the data storage unit 3 can be downloaded by transmitting analog data from the host computer 11.

FIG. 3 shows another embodiment of the present invention, and shows a block configuration of a measuring terminal device 10 having a built-in arithmetic processing program. The non-volatile semiconductor memory 4 is built in the measurement terminal device 10 by bus connection, and a dip switch 5 is provided on the panel surface. The dip switch 5 is connected to the bus by an interface circuit 6. Memory 4
, All arithmetic processing programs for each measurement signal are written by function, and among these programs, the digital arithmetic unit 2 determines the program specified by the dip switch 5 and stores the specified program from the memory 4. Read and execute arithmetic processing.

[0027]

As described above, according to the present invention, various measured analog signals are temporarily converted into digital quantities and collected,
Various operations are performed by digital operation, and the operation results are converted back to analog signals and transmitted to the higher-level device. Therefore, various operation functions can be realized with a software configuration, eliminating the need for a hardware circuit for each operation function. Therefore, the size and cost of the device can be reduced.

Further, the change of the arithmetic function or the like can be achieved only by changing the program from the outside, and the redesign for each arithmetic function is not required.

Further, the operation does not become unstable due to aging or the like, and maintenance and inspection are almost unnecessary.

Particularly, in an existing remote monitoring control system or control system that transmits a measurement signal in an analog manner, it is only necessary to replace an existing measurement terminal device.

[Brief description of the drawings]

FIG. 1 is a block configuration diagram of a measurement terminal device according to an embodiment of the present invention.

FIG. 2 is a configuration example of a measurement system using the measurement terminal device of the present invention.

FIG. 3 is a block diagram of a measuring terminal device according to another embodiment of the present invention.

[Description of Signs] 1 ... I / O circuit 2 ... Digital operation unit 3 ... Data storage unit 4 ... Nonvolatile semiconductor memory 5 ... Dip switch 6, 10C ... Interface circuit 10 ... Measurement terminal device 10B ... Data communication connector 13 ... Portable Type personal computer

Claims (2)

[Claims] 1. A measurement terminal device for performing various function calculations on various measurement signals that become analog signals and transmitting the calculation results to a higher-level device via an analog transmission path. An input means for converting the measurement result into a digital quantity, capturing the measurement signal converted into the digital quantity, performing a digital calculation for each calculation function with a software configuration for each calculation function, converting the calculation result into an analog signal, An output means for outputting to an analog transmission path. 2. A measuring terminal device, comprising: means for externally downloading the program and setting data to the data storage unit to change an arithmetic function.