JPH033896B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improvement in a pressure measuring instrument that uses a microprocessor to perform correction processing such as linearization and temperature correction.

[Technical background of the invention and its problems]

With the development of microprocessors, they have come to be increasingly used for signal processing in various process measuring instruments. Conventionally, a pressure measuring device using such a microprocessor includes a pressure detection circuit 1 that detects pressure and converts it into a digital signal, a temperature detection circuit 2, a microprocessor 3, and a memory for signal processing procedures, as shown in FIG. A measuring instrument main body 7 includes a first non-volatile read-only memory 4 for storing processing parameters, a second non-volatile read-only memory 5 for storing processing parameters, and an input/output circuit 6.
The measuring instrument main body 7 is adapted to exchange data with an external device (for example, a process control device) 10 via its own input/output circuit 6. In this measuring instrument main body 7, a microprocessor 3
performs necessary processing of the pressure detection signal of the pressure detection circuit 1 based on the processing procedure and processing parameters of the first and second dedicated memories 4 and 5, and since the pressure detection circuit 1 has temperature dependence, The temperature detection signal from the temperature detection circuit 2 is taken in, the non-linearity correction processing of the pressure detection circuit 1 is performed in addition to the above processing, and the data after the correction is sent to the input/output circuit 6.
It is given to the external device 10 via. In addition, the first
The second dedicated memories 4 and 5 are nonvolatile ROMs because it is necessary to store programs such as processing procedures for an appropriate period of time, and because it is difficult to constantly supply power. ing.
In the figure, P indicates pressure and T indicates temperature.

By the way, in a pressure measuring device that processes data using the microprocessor 3, data processing is performed by the microprocessor 3 while taking into account the individual differences of the device, so-called instrumental differences, during manufacturing and calibration of the device. It's summery. For this reason, the second dedicated memory 5 is constructed so that it can be inserted and removed as shown in FIG. 2, and when necessary, it can be removed, the processing parameters rewritten, and then inserted back into the specified position. This series of parameter rewriting work is complicated, and since the lid 8 has to be opened to remove the memory 5, the thermal equilibrium state inside the device is different from that during use, and the accuracy of the temperature correction process is lost. There are some drawbacks.

[Purpose of the invention]

The present invention enables processing parameters to be rewritten under specific conditions without opening the lid of the equipment, maintains a thermal equilibrium state inside the equipment, and prevents processing parameters from volatilizing due to erroneous operation. An object of the present invention is to provide a pressure measuring device using a microprocessor.

[Summary of the invention]

The present invention includes: an electrically readable and writable memory for storing processing parameters; and a read-only memory for storing keywords and processing procedures;
and a locking switch, and when data matching the keyword is input from an external device and specific data is input from the locking switch, the readable and writable memory is rewritten according to the processing procedure. It is a pressure measuring device that makes it possible.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 3 and 4. In these figures, the same parts as in FIGS. 1 and 2 are given the same reference numerals and detailed explanations will be omitted. In particular, in this pressure measuring device, the differences from the conventional one are described.
A non-volatile memory 11 such as EEP-ROM (Electrically Erasable-PROM) is provided to store and hold processing parameters. As this EEP-ROM, for example, 2816EEP-ROM manufactured by Intel Corporation of the United States is used. Second, a lock switch 12 is provided in the microprocessor 3, and when the lock switch 12 enters a predetermined switching state, for example, a switch on, using a key 13, data is written in the non-volatile memory 11 to the microprocessor 3. give a replacement order. Third, a non-volatile read-only memory 4' such as a ROM for storing processing procedures is provided, a series of predetermined data (keywords) A is stored in this memory, and further input/output from external equipment (e.g. process control equipment) 10 is provided. the series of data received through the circuit 6 and the series of data A match;
In addition, a processing procedure B is stored and retained, which enables rewriting of data in the nonvolatile memory 11 when the lock switch 12 is turned on at that time, and prohibits rewriting when it is not. Note that the series of data A to be stored and retained in the non-volatile read-only memory 4' is, for example, a series of ASCII codes CALBcr (cr is carriage return), and processing parameters are not rewritten due to erroneous operation or the like. Make sure there is no such thing. Further, the lock switch 12 is attached to the panel surface 7a of the measuring instrument main body 7, as shown in FIG.

Next, the operation of the pressure measuring device configured as described above will be explained. The pressure detection circuit 1 detects the pressure P, converts it into a digital pressure detection signal, and supplies it to the microprocessor 3. The temperature detection circuit 2 similarly detects the temperature T, converts it into a digital temperature detection signal, and then supplies it to the microprocessor 3. Here, the microprocessor 3 follows the preprocessing procedure of the nonvolatile read-only memory 4', reads out the processing parameters of the nonvolatile memory 11, and performs processing such as linearization and temperature correction on the pressure detection signal. It is transmitted to the external device 10 via the input/output circuit 6.

Next, when calibrating the device, the measuring device main body 7 is installed in a constant temperature bath, and this measuring device main body 7 has an external device 10 such as a standard pressure generator for calibration, etc.
A calibration facility consisting of a temperature control device and a control computer is connected. Then, a predetermined temperature and reference pressure are applied to the measuring instrument main body 7 by a control computer. At that time, switch 1 with lock
The key 13 is inserted into the key 2 and the lock switch 12 is turned on to enable data to be rewritten, and at the same time a series of data such as a CALBcr code is sent out from the control computer. This series of codes is input to the microprocessor 3 via the input/output circuit 6. When a series of data is input from the external device 10, the microprocessor 3 compares the data with the series of data A in the non-volatile read-only memory 4', and if they match, it further processes the data in the dedicated memory 4'. Based on procedure B, the write command from the lock switch 12 is sent to the non-volatile memory 1.
It is determined that rewriting to 1 is permitted. and,
The microprocessor 3 obtains processing parameters so that the output data of the device has correct values, and rewrites the processing parameters into the nonvolatile memory 11. In practice, processing parameters such as linearization and temperature correction are optimized and calibration is completed by performing calibration for each pressure and temperature. After the calibration, the lock switch 12 is turned off, and according to processing procedure B, rewriting of data in the nonvolatile memory 11 is prohibited, and the memory 11 stores and holds the calibrated processing parameters.

Therefore, according to the configuration of the embodiment as described above,
An electrically readable and writable non-volatile memory 11 is used to store and hold processing parameters, and a lock switch 12 is turned on and off, e.g.
Since the CALBcr keyword is used to perform the processing procedure of rewriting and prohibiting the memory 11, the processing parameters will not be volatile due to a power supply stoppage, and will also be destroyed due to an erroneous operation. There will be no more chance of being attacked. Moreover, since the non-volatile memory 11 can be electrically written to, it is no longer necessary to open the lid 8 of the device even when processing parameters are changed during calibration, for example. You will no longer have to worry about not being able to ask for anything.

In the above embodiment, the ASCII code CALBcr is used as the keyword, but it goes without saying that a character string or binary code that cannot be used for normal data exchange may also be used. Also, instead of the lock switch 12, for example, an electronic switch circuit may be used, and when this switch circuit is turned on a predetermined number of times, it is assumed that a rewriting command is issued, or a code signal consisting of on and off signals is used. It may be given a meaning that it is a rewrite command. Alternatively, it may be a switch with a lid and a lock. In addition, the present invention can be implemented with various modifications without departing from the gist thereof.

〔Effect of the invention〕

As detailed above, according to the present invention, an electrically readable and rewritable memory is used to store and retain processing parameters, and rewriting of this memory is protected by a lock switch and a keyword. , the processing parameters will not be destroyed due to erroneous operation, and the processing parameters can be changed under specific conditions without opening the lid of the equipment or being manipulated from outside without permission.
The inside of the device can be calibrated while maintaining a thermal equilibrium state similar to that during actual use, and as a result, a pressure measuring device can be provided that can ensure accurate temperature correction.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a conventional pressure measuring device.
FIG. 2 is a state diagram of the inside of the device when the lid is opened, FIG. 3 is a block configuration diagram showing one embodiment of the pressure measuring device according to the present invention, and FIG. 4 is a conceptual diagram showing the external appearance of the device. 1...Pressure detection circuit, 2...Temperature detection circuit, 3
...Microprocessor, 4'...Nonvolatile read-only memory, 6...Input/output circuit, 7...Measuring instrument body, 10...External equipment, 11...Nonvolatile memory, 12...Lock switch.

Claims (1)

[Claims] 1. A pressure measuring instrument in which a microprocessor performs correction processing on a pressure detection signal detected by a pressure detection circuit based on the detected temperature of outside air, wherein an external device is connected to the microprocessor when necessary. an input/output circuit that is connected to the microprocessor and controls the exchange of data between the microprocessor and external equipment; and an electric circuit that is connected to the microprocessor and stores the processing parameters necessary for the correction processing and other data processing. a non-volatile memory that can be read and written cyclically; a non-volatile read-only memory that is connected to the microprocessor and stores keywords and processing procedures in advance; A locking switch is provided on the outside of the casing, and provides commands to rewrite processing parameters to the microprocessor without opening the lid when necessary; The non-volatile memory can be rewritten when the data and the predetermined keyword match and a command to rewrite the processing parameters is received from the lock switch, and the non-volatile memory can be rewritten based on the data from the external device. A pressure measuring instrument comprising: a processing parameter changing means for changing the processing parameters, and rewriting the processing parameters while maintaining a thermally parallel state within the outer casing. 2. The pressure measuring device according to claim 1, wherein the lock switch is an electronic switch that is turned on a predetermined number of times.