JPH07119631B2 - Process converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to an ambient temperature of a differential pressure converter, an electromagnetic flow meter, or the like,
The present invention relates to a process converter that measures environmental variables such as humidity and vibration and collects the data, and particularly relates to a process converter that can efficiently collect the data.

<Prior Art> Most process converters for signal conversion of process variables such as differential pressure, pressure, and flow rate are composed of electronic circuits containing semiconductor elements, and there is also a demand for intelligent process converters. , Process converters are now incorporating microprocessors.

Since these miniaturized process converters are installed near where process pipes, tanks, etc. are installed, they are exposed to severe environmental conditions such as temperature, humidity, and vibration.

Therefore, process converters, which are miniaturized of electronic parts and heavily used with high-density patterned semiconductors, are becoming more and more disadvantageous in terms of environmental resistance. For this reason, understanding the environmental conditions in which the process converter is installed is an important factor in promoting the reliability design of the process converter.

Therefore, conventionally, a process converter is designed by predicting expected temperature, humidity, vibration, etc., or empirically setting the environmental resistance condition of the process converter by referring to past data. Is the current situation.

<Problems to be Solved by the Invention> However, such a conventional data collection method copes with changes in environmental conditions, changes in environmental resistance of circuit components, or special environmental conditions of the installed process converter. Data cannot be obtained, and when an accident occurs due to the installation environment of the process converter, data such as the environmental conditions corresponding to this accident cannot be accurately obtained, making it difficult to take countermeasures against the accident. is there.

<Means for Solving Problems> In order to solve the above problems, the present invention has a process sensor for measuring a process variable and outputs a process signal corresponding to the preceding process variable via two transmission lines. In the two-wire process converter that transmits to the receiver side by the environment, an environmental sensor that is provided in the vicinity of the preceding process sensor and measures the environmental variable unique to the preceding process converter, and environmental data corresponding to this environmental variable Of the digital signal transmitted from the receiver side via the non-volatile memory that is connected to the previous transmission line and this transmission line is decoded. And a communication means for sending environmental data corresponding to the contents of the destination to the transmission line of the destination, and the accumulated environmental data of the destination is needed through the communication means of the destination. Depending on It is designed so that it can be taken out.

<Operation> The environment sensor built into the process converter measures the environmental variables unique to this process converter, and this is always stored and stored in the non-volatile memory, and this data is read out as necessary. To collect data.

<Embodiment> FIG. 1 is a block diagram illustrating one embodiment of the present invention.

The embodiment shown in the figure is a case in which an environment sensor is built in a differential pressure transducer for measuring a differential pressure of an orifice attached to a pipe in order to measure a flow rate which is a process variable in the pipe.
Here is an example:

10 is a capacitance type differential pressure sensor.
Form a pair of fixed electrodes opposed to the moving electrodes to form variable capacitors C ₁ and C ₂ that change complementarily to each other. The displacement due to the differential pressure applied to the moving electrode is converted by the differential pressure sensor 10 into changes in the variable capacitances C ₁ and C ₂ corresponding to this displacement, and further converted into a duty signal D by the capacitance / duty converter 11. Then, the converted duty signal D is output to the processor 12.

The processor 12 is an address decoder 13 that decodes the memory address, an EEPROM 14 that is a read-only memory that can electrically rewrite the stored contents, an erasable and rewritable read-only memory that is an EPROM 15, and a liquid crystal display. It is connected to an LCD driver 17 for driving the element 16 via a control bus 18, a data bus 19 and an address bus 20, and also receives timing pulses from a crystal oscillator 21.

Reference numeral 22 is a temperature sensor, 23 is a humidity sensor, and 24 is a vibration sensor.These functions as an environment sensor 25 as a whole, and the temperature is a specific element inside the process converter or an environmental variable such as the surrounding environment. Senses humidity, vibration, etc.
Each environmental variable from the environmental sensor 25 is converted into a digital signal by the analog / digital converter 26 and input to the processor 12, and the address decoder is controlled under the control of the processor 12.
The address is decoded by 13 and EEPROM 14 or EPRO
It is stored in a predetermined memory area such as M15 via the data bus 19.

These environmental data are variously processed by the processor 12 as necessary. For example, the maximum temperature, the minimum temperature, the maximum humidity, the minimum humidity, the maximum vibration degree, the minimum frequency, the maximum acceleration, and the minimum frequency within a day can be calculated. Processing such as recording of data and calculation of cumulative time with these effects will be performed.

Further, when the environmental condition exceeds the specification range, data can be written in a predetermined memory area such as the EEPROM 14 or the EPROM 15 and an alarm can be issued if necessary.

Further, the processor 12 uses the duty signal D from the capacity / duty converter 11 to modulate the pulse width signal P _W or the like corresponding to the displacement of the differential pressure sensor 10 and outputs it to the output circuit 27, or the duty signal D. On the other hand, if necessary, the environmental variable is used as the correction data for the variation of the environmental condition to improve the accuracy and output to the output circuit 27.

The output circuit 27 includes a receiving resistor R _L , terminals T ₁ and T ₂ , transmission lines l ₁ and l ₂ and terminals from an external power source E provided on the receiving end A side.
Using the current signal I _L transmitted to the process converter B side via T ₁ ′ and T ₂ ′, the circuit power supply of the process converter B is made and the pulse width corresponding to the flow rate detected by the differential pressure sensor 10 converts the signal P _W into a current signal I _L be transmitted to the receiving resistor R _L.

On the other hand, the process converter B as needed for the transmission line l _1, l ₂
A handheld terminal 29 for communication with can be connected.

The handheld terminal 29 accesses the processor 12 via the transmission lines l ₁ and l ₂ output circuit 27 and the communication interface 30 to set the span of the process converter B or store it in the EEPROM 14 or EPROM 15, for example. It reads out the environmental variables that are being used. In addition to this, it also has a function to read the current signal I _L if necessary.

The flow rate signal detected by the reception resistance R _L is received by the receiving device 28 or used for flow rate control or the like.

Further, at both ends of the receiving resistance R _L communication interface 3
0, data such as environmental variables transmitted via the output circuit 27 are also transmitted at the request, and at this time, these data are received by the receiving device 28 such as a computer, and data is analyzed when necessary. You can also do it.

<Effects of the Invention> As described above in detail with the embodiments, the present invention has the following effects.

(B) Data of the installation environment of the process converter has not been accumulated as data until now, but according to the present invention, reliable data can be automatically collected over a wide range, and an appropriate device design can be performed. .

(B) According to the present invention, the history of the environmental conditions remains in the process converter, so that even if a trouble occurs in the equipment, those based on the environmental conditions in use can be qualified and promptly investigated and improved.

(C) Since environmental conditions are constantly monitored, an alarm can be immediately issued when environmental conditions exceed equipment usage, and troubles such as damage to other plant equipment due to output abnormality can be prevented in advance. can do.

(D) Since the environmental history remains in the memory, maintenance can be performed according to the degree of stress received due to environmental conditions, which contributes to efficient maintenance and economic efficiency.

(E) Since the data on the installation environment of the equipment are available, the installation environment can be properly and economically maintained.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating one embodiment of the present invention. 10 ... Differential pressure sensor, 11 ... Capacity / duty converter, 12 ...
… Processor, 13 …… Address decoder, 14 …… EEPRO
M, 15 ... EPROM, 22 ... Temperature sensor, 23 ... Humidity sensor, 24 ... Vibration sensor, 25 ... Environment sensor, 26 ... Analog / digital converter, 27 ... Output circuit, 29 ... Handheld Terminal, 30 ... communication interface, A ...
… Receiving end, B …… Process converter.

Claims (1)

[Claims] 1. A two-wire process converter having a process sensor for measuring a process variable, wherein a process signal corresponding to the process variable is transmitted to a receiver side via two transmission lines. An environmental sensor that is provided in the vicinity of to measure an environmental variable unique to the process converter, a non-volatile memory that constantly stores changes in environmental data corresponding to the environmental variable and stores the environmental history, It is connected to a transmission line, decodes the request content of the digital signal transmitted from the receiver side through this transmission line, accesses the non-volatile memory, and sends environmental data according to the request content to the transmission line. A process converter comprising a communication unit, and the accumulated environmental data can be retrieved as needed via the communication unit.