JPH0827876B2 - Transmitter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention is a transmitter suitable for detecting an analog amount such as pressure or differential pressure which is an industrial process amount, and transmitting the signal to a main control room. Regarding

[Conventional technology]

This type of transmitter has various processes such as pressure and temperature as described in JP-A-59-114930 (the transmitter is called a sensor communication device in JP-A-59-114930). Having a plurality of sensors for detecting a quantity, selecting one of these sensors via an input multiplexer and amplifying the selected sensor output signal with a variable gain amplifier,
The signal amplified by this variable amplifier is compared with the triangular wave signal from the free-running triangular wave generator through the comparator to generate a variable duty cycle signal corresponding to the sensor output signal,
After converting this duty cycle signal into a digital word (digital signal), digital signal processing is performed by the digital signal processing means according to a fixed procedure (program), and finally the signal is normalized via the D / A converter. (For example, 4 to 20 mA) is obtained. Also,
It has an input selector that controls the input multiplexer and a range selector that selects the gain level of the amplifier.

That is, the digital signal processing means receives the above-mentioned digital word, and creates data corresponding to the digital word and an analog input signal stored in a digital memory in advance (this created data is known in the transmitter manufacturing process as described later). For obtaining a true input value (in other words, a normalized sensor output signal) according to a predetermined program based on the analog input added to the sensor and using a production computer to function as a so-called calibration curve. Digital signal processing.

When manufacturing a transmitter, a production computer is connected to the pressure receiving housing, an analog input for a known process quantity is added to the sensor, and data corresponding to the analog input signal (eg, process variable (analog input) -sensor output identification). Is generated by a production computer and stored in the digital memory of the digital signal processing unit. At the time of measurement, the signal from each sensor is converted into a digital word by the A / D converter as described above, and a true input value is obtained from the digital data and the created data previously stored in the digital memory.

[Problems to be Solved by the Invention]

Generally, this type of transmitter includes a pressure-receiving housing that includes a sensor that receives pressure and converts the pressure into an analog signal, a variable gain amplifier that amplifies the analog signal from the sensor, and an A / D that converts the analog signal into a digital word. A converter, a processing unit housing including an electronic circuit (digital signal processing means and D / A converter, V / I converter) for converting the digital signal into a normalized signal (for example, a current signal of 4 to 20 mA); Composed of. The pressure receiving housing and the processing unit housing are
They are manufactured separately and combined at the time of shipping.

By the way, conventionally, since the processing unit housing has a digital memory for storing created data (data created by the above-mentioned production computer) corresponding to each analog input signal, this processing unit housing is
It must be associated with a pressure-receiving housing corresponding to the production data stored in its own digital memory. If a pressure-receiving housing that does not correspond to the data stored in this digital memory is combined, the characteristics will be deteriorated. In the above-mentioned conventional transmitter, there is a problem that it is not easy to find out if they are incorrectly combined.

It is an object of the present invention to provide a transmitter that can be easily understood even if the combination of the pressure receiving housing and the processing unit housing is mistaken or is not mistaken.

[Means for solving the problem]

In order to achieve the above-mentioned object, the present invention is basically configured as follows.

That is, a sensor that detects a process amount such as pressure, a programmable gain amplifier that amplifies the sensor output signal, an A / D converter that performs analog-digital conversion of the amplified sensor output signal, and a digital signal from this A / D converter. The sensor output signal is normalized according to a predetermined program from the data and the data corresponding to the analog input signal of the sensor (created data) created and stored in advance by adding the analog input related to the known process amount to the sensor. In a transmitter including digital signal processing means for processing a digital signal, a transmitter main body is composed of a combination of a pressure receiving housing and a processing portion housing, and the digital signal processing means is provided on the processing portion housing side. Before instructing the microprocessor to be configured and the operation of the microprocessor A digital memory for storing a program is provided, and in addition to the sensor, the programmable gain amplifier, the A / D converter, and the programmable read only memory (hereinafter, referred to as PROM) for storing the created data are provided on the pressure receiving housing side. ) Is provided, the gain selection of the program gain amplifier is controlled by the microprocessor on the processing unit housing side, and the PROM creation data necessary for the digital signal processing executed in the processing unit housing is received by the pressure receiving unit. It was set to call from the housing side.

In addition, the PROM stores, in addition to the created data, data indicating an identification of each pressure receiving housing, and the processing unit housing recognizes the data indicating the identification and receives a pressure to be combined. It is also proposed that the housing be configured so that it can be discriminated whether or not it is the desired one.

[Action]

Data corresponding to the analog input signal of the sensor is created and stored in advance in the PROM provided on the pressure receiving housing side.
This created data can be used, for example, by connecting a pressure-receiving housing to a production computer in the transmitter manufacturing process, adding a known analog input (process amount) to the sensor, and converting the sensor output to A / D conversion on the pressure-receiving housing side. Then, this A / D converted data is collected by a production computer and processed into suitable data (data corresponding to an analog input signal that can function as a calibration curve). Store in ROM writer.

Then, the transmitter main body is configured by combining the processing unit housing and the pressure receiving housing.

Then, at the time of actual measurement, on the pressure receiving housing side, a process amount such as pressure is detected by a sensor, a detection signal is amplified by a programmable gain amplifier, and analog-digital conversion is performed by an A / D converter. On the processing unit housing side, a digital signal for normalizing the sensor output signal according to a predetermined program from the digital signal from the A / D converter and the created data previously stored in the programmable read only memory. The processing is performed (in other words, the digital signal obtained from the pressure receiving housing side is converted into a digital signal which is a basis of the normalized signal by the digital signal processing means on the processing section housing side), and finally, for example, The digital output signal from the digital signal processing means is converted into a normalized analog signal (for example, 4 to 20 mA) by the D / A converter and transmitted.

Further, according to the present invention, the element (sensor, programmable gain amplifier) having characteristics in the transmitter is unique.
Is provided on the pressure receiving housing side, and the created data corresponding to the analog input signal of the sensor is stored in the PROM and provided on the pressure receiving housing side. On the other hand, the processing unit housing side has a digital processing means with little individuality. (A digital memory storing a microprocessor and a fixed program serving as its operating procedure) is provided, and the gain selection of the program gain amplifier on the pressure receiving housing is controlled by the microprocessor on the processing unit housing side.
Moreover, since the PROM data necessary for the digital signal processing executed in the processing unit housing is called from the pressure receiving housing side, the processing unit housing can be shared by the individual pressure receiving housings. In other words, the processing unit housing is compatible with the pressure receiving housing, and there is no room for error in the combination of the pressure receiving housing and the processing unit housing.

Furthermore, the PROM also stores data indicating the identification of each pressure receiving housing, and the processing unit housing recognizes the data indicating the identification and determines whether the pressure receiving housing to be combined is the desired one. Even if the pressure-receiving housing to be used is specified, if the configuration is such that it can be discriminated, if the combination is wrong, it is possible to easily notify the mistake. For example, in the manufacturing process of the transmitter, when the production computer is first connected to the pressure receiving housing, the identification data is written in the PROM in the pressure receiving housing. Also, the same identification data should be written in the digital memory of the processing unit housing. Then, if the operation of the microprocessor is determined so as to compare the identification data of each when the pressure-receiving housing and the processing unit housing are combined, it is easy to understand that they are mistakenly combined.

〔Example〕

The present invention will now be described with reference to the embodiments shown in FIGS. 1 and 2 and the third embodiment.
This will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the transmitter of the present invention. In FIG. 1, 10 is a processing unit housing, 20 is a pressure receiving housing, and these housings 10 and 20 constitute a transmitter main body.

The pressure receiving housing 20 has a sensor (for example, a differential pressure sensor 21, a temperature sensor 21, a static pressure sensor 23) for detecting a plurality of process variables and a zero circuit 24. The zero circuit 24 is a multiplexer for selecting each sensor. 25, a programmable gain amplifier 26 capable of selecting a suitable gain according to the sensor sensitivity of each analog input, an A / D converter 27 for converting an analog amount into a digital word (digital value), an interface 28, The pressure receiving housing 20 is connected to the processing circuit 11 of the processing unit housing 10 via the interface 28.

Furthermore, like the multiplexer 25, programmable gain amplifier 26, and A / D converter 27, the PROM (programmable
A read only memory) 29 is built into the pressure receiving housing 20 and connected to the interface 28.

On the other hand, a digital processing circuit (digital signal processing means) 11 which is the center of the processing unit housing 10 is provided inside, and the digital processing circuit 11 is a microprocessor 11
And a digital memory 111 storing a fixed program relating to the operation procedure. Further, the processing unit housing 10 includes a D / A converter 121 for digital-analog converting the digital output signal from the microprocessor 11.
And a V / I (voltage-current) converter 122 and a digital transmission / reception device 123. D / A converter 121, V / I converter 12
2. A communication interface that communicates with an external central control unit (process control unit) using the transmission / reception device 123.
12 are composed.

The production computer 30 is connected to the pressure receiving housing 20 via the interface 28 in the transmitter manufacturing process, and adds known analog inputs (process amounts relating to differential pressure, temperature, static pressure) to the respective sensors 21, 22, 23, The data obtained therefrom is collected and processed to create data corresponding to the analog input signal (for example, function approximation data indicating the input-output characteristics of the sensor), and this created data is stored in the PROM 29. At the same time, the identification data of the pressure receiving housing 20 is written in the PROM 29 and also in the digital memory 111 of the processing circuit 11. In addition, at the check points in the course of manufacturing (for example, a leak test after welding of each component of the pressure receiving housing 20, an airtight test after a flange assembly for introducing pressure to the pressure receiving housing 20, etc.), the production computer 30 is used. Write in the PROM 29 whether or not the process is completed and the date.

In this embodiment, the pressure receiving housing 20 is used during the actual measurement.
On the side, the sensor outputs of the sensors 21 to 22 are selected by the multiplexer 25, the output signal (sensor detection signal) from the input multiplexer 25 is amplified by the programmable gain amplifier 26, and the amplified analog signal is the A / D converter. Converted to digital words by 27.

On the processing housing 10 side, the microprocessor 112
Interface the digital signal from the / D converter 27
For calling the created data corresponding to the analog input signal of the sensor previously stored in the PROM 29, and normalizing the sensor output signal according to a predetermined program from this digital signal and the created data of the PROM 29. Performs digital signal processing. In other words, the digital word obtained from the pressure receiving housing 20 side is converted into the digital word which is the basis of the normalized signal in the digital signal processing circuit 11 on the processing unit housing 10 side. Then, the digital output signal from the digital signal processing circuit 11 is transferred to the D / A converter 12
It is converted into a normalized analog signal (for example, 4 to 20 mA) by the 1, V / I converter 122. This 4-20 mA analog signal is delivered to analog signal output line 13 for use in controlling and communicating with an industrial process (not shown). The digital transmission / reception device 123 also performs digital communication with a device (not shown) connected to the output line 13.

According to the present embodiment, the elements (sensors 21 to 23, programmable gain amplifier 2
6) is provided on the pressure receiving housing 20 side, and the created data corresponding to the analog input signal of the sensor is also PROM29.
Is provided on the pressure-receiving housing side 29, and on the other hand, on the processing section housing 10 side, digital processing means (microprocessor 112 and a digital memory 11 storing a fixed program as an operating procedure thereof) having almost no individuality.
1) is provided so that the gain selection control of the program gain amplifier 26 on the pressure-receiving housing 20 side and the control of the multiplexer 25 are performed by the microprocessor 112 on the processing section housing 10 side, and are executed by the processing section housing 10. Since the data of the PROM 29 necessary for digital signal processing is called from the pressure receiving housing 10 side, the processing unit housing 10 can be commonly used for each pressure receiving housing. That is, the processing unit housing 10 is compatible with the pressure receiving housing 20, and it is possible to eliminate the possibility of making a mistake in the combination of the pressure receiving housing 20 and the processing unit housing 10.

In addition, the PROM 29 of the pressure receiving housing 20 and the processing unit housing
Since the program of the multiprocessor 112 is prepared so as to compare the identification with the memory 111 in the processing circuit 11 of 10, the desired pressure receiving housing 20 used by the processing unit housing 10 is identified through the identification. By specifying, even if the combination of the pressure receiving housing 20 and the processing unit housing 10 is mistaken, it can be easily understood. Further, since the management data in the middle of the process can be written in the PROM 29 online without human intervention, there is no error in transcription or input.

FIG. 2 is a detailed block diagram showing an embodiment of the pressure receiving housing 20 of FIG.

The interface 28 shown in FIG. 1 is, in detail, a transceiver 281, a latch A 282, a latch B (two pieces) 283,284,
It is composed of a latch C285, an AND gate 286 and a decoder 287. The transceiver 281 and the latches 282 to 285 are connected to eight data buses of an MPU (micro processing unit, for example, HD6301) 112 on the processing unit housing 10 side. Latch B283,284 is PROM2 by microprocessor 112
The address data for addressing to 9 is latched so that the data bus is also used as the PROM address bus. What is commonly used in this way is that when the PROM 29, the multiplexer 25, the program gain amplifier 26, and the A / D converter 27 are provided on the pressure receiving housing side, the wire harness for connection with the processing unit housing 10 increases. This is because there is a tendency to rationalize the wire harness.

Also, the decoder 287 is connected to the microprocessor 112 via a decoding address line, is selectively enabled by a decode address command from the microprocessor 112, passes data to and from the PROM 29 via a latch A, and via a latch C285. The A / D converted data is read, the gain of the programmable gain amplifier 26 and the sensor are selected.

Writing and reading of data to PROM29 is performed like the time chart shown in Fig. 3, ▲ ▼ (Prog
ram Emable) to enable PROM29 ▲
▼ is enabled. Write the address of PROM29 to the latch B283,283 via the data bus and latch the data
After writing to A282, apply V _pp (for example, + 21V when using HN27 series as PROM29), and
Data is stored in the PROM 29 by enabling the.

When reading data from PROM29, set the address and then enable ▲ ▼ 1 to set PROM29
▲ ▼ enabled, and transceiver 281
Is enabled and the data in PROM29 is output to the data bus. At this time, ▲ ▼ (Output C of latch A282
ontrol) and connect ▲ ▼ 1 to the data of latch A282
It is necessary to avoid collision with the data in PROM29.

EEPROM that can be electrically written and erased as PROM29
By using, it is possible to easily deal with an application depending on the shape of the pressure receiving housing 20.

〔The invention's effect〕

As described above, according to the present invention, it is possible to obtain a transmitter that can be easily understood even if the combination of the pressure receiving housing and the processing unit housing is mistaken, or is not mistaken, and it is possible to improve the productivity. effective.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the transmitter of the present invention,
2 is a detailed block diagram showing an embodiment of the pressure receiving housing of FIG. 1, and FIG. 3 is an operation time chart of the block diagram shown in FIG. 10 ... Processor housing, 11 ... Processing circuit (digital signal processing means), 12 ... Communication interface, 13 ...
Signal output line, 20 …… Housing, 21-23 …… Sensor, 25
...... Multiplexer, 26 …… Programmable gain amplifier, 27 …… A / D converter, 28 …… Interface, 29…
… PROM (Programmable Read Only Memory), 111 …… Digital memory, 112 …… Microprocessor, 121 …… D / A converter.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junichi Makino 4026 Kuji Town, Hitachi City, Hitachi, Ibaraki Prefecture Hitate Manufacturing Co., Ltd.Inside Hitachi Research Laboratory (72) Inventor Shinichi Sakamoto 4026 Kuji Town, Hitachi City, Ibaraki Prefecture Hitate Manufacturing Co., Ltd. Hitachi Research Laboratory (72) Inventor Yukio Ito 882 Ige, Katsuta-shi, Ibaraki Hitachi Measurement Engineering Co., Ltd. (56) References JP 59-114930 (JP, A) JP 60-105098 (JP, A)

Claims (3)

[Claims] 1. A sensor for detecting a process amount such as pressure, a programmable gain amplifier for amplifying the sensor output signal, an A / D converter for analog-digital converting the amplified sensor output signal, and this A / D converter. According to a predetermined program, the digital data from the sensor and the data corresponding to the analog input signal of the sensor (hereinafter, referred to as generated data) which is generated and stored in advance by adding the analog input related to the known process amount to the sensor. In a transmitter provided with a digital signal processing means for performing digital signal processing for normalizing a sensor output signal, the transmitter main body is composed of a combination of a pressure receiving housing and a processing unit housing, and the processing unit housing side A microprocessor that constitutes the digital signal processing means, and A digital memory for storing the program for instructing the operation is provided, and in addition to the sensor, the programmable gain amplifier, the A / D converter, and the programmable read only memory for storing the created data are provided on the pressure receiving housing side. Providing the programmable read only memory for controlling the gain selection of the program gain amplifier by the microprocessor on the side of the processing unit housing and performing the digital signal processing executed in the processing unit housing. A transmitter, wherein data is set to be retrieved from the pressure receiving housing side. 2. The programmable read-only device
The memory stores, in addition to the created data, data indicating an identification of each pressure receiving housing, and the processing unit housing recognizes the data indicating the identification and desires a pressure receiving housing to be combined. The transmitter according to claim 1, characterized in that it can be discriminated whether or not the transmitter. 3. The pressure receiving housing side is provided with a plurality of sensors for detecting various process quantities and an input multiplexer for selecting and inputting one of these sensor output signals. The transmitter according to claim 1 or 2, wherein the output signal of (1) is amplified through the programmable gain amplifier.