JPS61248102A - Process controller - Google Patents

Abstract

PURPOSE:To prevent the occurrence of down state of a microprocessor against noise by providing an interruption signal generating section that generates an interruption signal responding to a noise detection signal from a noise detecting section and a microprocessor that executes a noise processing program responding to input of the interruption signal. CONSTITUTION:When noise above specified threshold level is inputted to a noise detecting section 44, a noise detection signal is outputted from the noise detecting section and this is inputted to an interruption signal generating section 48. The interruption signal generating section 48 generates an interruption signal responding to the noise detection signal and gives this interruption signal to a microprocessor 12. Consequently, the microprocessor becomes the state of interruption, and performs the restoring process from an unstable state of each circuit due to noise by executing specified noise processing program, and returns to original program and continues adjusting function.

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to a process controller, and in particular, a process controller that is less susceptible to external impulsive noise and has improved stability and reliability. Regarding process controllers.

(b) Prior art and its problems In conventional process controllers, there is an analog signal input/output section that inputs and outputs analog signals, a digital signal input/output section that inputs and outputs digital signals, and signals of these signal input/output sections. There are some that are equipped with a microprocessor that processes these and a power supply section for them.

By the way, this type of conventional digital process controller is configured to include a noise filter or the like in the input/output line section to reduce noise entering from the common line.

However, when noise enters between the common line and the case, the noise reduction effect is small, especially in floating type and output type process controllers, and therefore,
The microprocessor built into the process controller goes down, causing a phenomenon in which the ability to adjust various process instruments is lost.

In order to prevent this, some conventional devices have installed a filter between the common line and the case in addition to the input/output signal line section, but this can have a negative effect on analog input/output signals, and Even if measures were taken, it was not always possible to completely prevent the effects of noise. Furthermore, noise that enters from the input/output line section passes through the power supply section and is grounded, so a pulse signal is generated on the common line of the digital circuit, and as a result, the microprocessor may go down as described above. There was a problem.

As a measure to reduce such noise, the common line on the input/output side is completely separated from the common line on the digital processing side by using an isolation amplifier for the analog input/output section and a photo coupler for the digital input/output section. There have been proposals for a method in which all input and output is done digitally via optical fiber. However, in the former case, it cannot be completely prevented due to crosstalk on the mounting board.
Furthermore, in the latter case, the system configuration becomes complicated, and if the receiver installed on the terminal side uses a microcomputer or the like, a down state occurs in the same way as described above.

Moreover, recent digital process controllers have a large number of input/output points for various process instruments, so if all the points are separated for noise countermeasures, it is necessary to connect them to the process instruments from the center of the control system of the process controller. Problems arise, such as extra costs for the peripheral parts.

The present invention has been made in view of the above circumstances, and is designed to prevent the microprocessor from going down due to noise that enters from the input/output section and the power supply section, thereby ensuring that the process instrument is always properly connected to the process instrument. The purpose is to enable efficient control operations and to reduce the cost of the device metal body.

(C) Means for Solving the Problems In order to achieve the above object, the present invention provides a noise detection unit that outputs a noise detection signal in response to a noise input of a predetermined threshold level or higher; A process controller includes an interrupt signal generator that generates an interrupt signal in response to a noise detection signal from a noise detector, and a microprocessor that executes a noise processing program in response to input of the interrupt signal. ing.

(iv) When noise of a predetermined threshold level or higher is input to the effect noise detection section, a noise detection signal is outputted from the noise detection section and is inputted to the interrupt signal generation section. The interrupt signal generator generates an interrupt signal in response to the noise detection signal and provides the interrupt signal to the microprocessor.

As a result, the microprocessor enters an interrupt state, executes a predetermined noise processing program to restore each circuit from an unstable state caused by noise, and then returns to the original program and continues the adjustment function.

(e) Examples Hereinafter, the present invention will be explained in detail based on examples shown in the drawings.

FIG. 1 is a block diagram of a process controller according to an embodiment of the present invention. In the figure, numeral 1 is a process controller, 2a to 2n are signal input terminals for inputting analog signals output from process instruments not shown, and 2x is a common line. 4 is an input amplifying section that amplifies the analog signal input manually to the signal input terminal 2; 6 is an input multiplexer that sequentially switches and inputs the analog signal amplified by the input amplifying section 4; and 8 is an input multiplexer that is input via the input multiplexer 6. This is an A/D converter that digitizes analog signals.

10 is a data memory unit that stores various input data; 12 is a microprocessor that processes input/output data and controls the operation of each unit; and executes a noise processing program in response to an interrupt signal; and 14
is a program memory section in which operating programs for the microprocessor 12 are stored. 16 is a data bus, 18
is the control bus.

20 is a D/A converter that converts the process control signal outputted from the microprocessor I2 into analog; 22 is a D/A converter;
An output demultiplexer that sequentially switches the process control signal converted into analog by the converter 20; 24 is an output amplification section that amplifies the process control signal that has passed through the output demultiplexer 22; and 26a to 26n are process control signals from the output amplification section 24. The signal output terminal 26x is a common line.

28a to 281 are signal input terminals for inputting digital signals output from process instruments not shown, and 28X is a common line. 30 is an input buffer section that temporarily stores digital signals input to the signal input terminal; 32 is an output buffer section that temporarily stores process control signals output from the microprocessor IO; 34a to 341 are output buffer sections 3
The output terminal 34x of the process control signal from 2 is a common line.

36 is a power supply unit for each part including the microprocessor 12;
8 is a power input terminal.

Further, 40a to 40d are noise filters, 42a to 42
c is an interface.

Noise detectors 44a to 44d output a noise detection signal in response to input noise of a predetermined threshold level or higher. As shown in FIG. 2, each of these noise detection units 44a to 44d has a
Each of them is composed of a delay element 50 and an exclusive OR circuit 52. Further, 46 indicates each noise detection unit 44a to 44d.
an OR circuit section that inputs the noise detection signal output from the
Reference numeral 48 denotes an interrupt signal generating section that generates an interrupt signal in response to the noise detection signal passed through the OR circuit section 46, and in this example, the interrupt signal generating section 48 is composed of an RS flip-flop. The Q output terminal of this RS flip-flop 48 is connected to the microprocessor 1.
It is connected to the interrupt terminal INT of No. 2.

In the process controller 1 of this embodiment, when noise enters from one of the common lines 2x, 26X, 28X, and 34X of each input/output terminal, for example, 2x, the noise is transmitted to the delay element 50 of the noise detection circuit 44a. After being delayed for a certain period of time, the signal is input to one input terminal of the exclusive OR circuit 52. Since the other input terminal of the exclusive OR circuit 52 is always set to a low level, if the level of the noise that has entered exceeds a predetermined threshold level, the noise is recognized as noise by the exclusive OR circuit 52. Output as a detection signal. In this way, the noise detection section 4
The noise detection signal outputted from 4a is passed through an OR circuit 46 to the RS flip-flop 4, which is an interrupt signal generator.
It is input to the set input terminal S of No. 8. This allows RS
Flip-flop 48 is set and an interrupt signal is output from its Q output terminal. This interrupt signal is sent to the interrupt terminal of the next stage microprocessor 12.
Input to NT. This places the microprocessor in an interrupt state.

The microprocessor 12 that has entered the interrupt state receives the RS
A reset signal is output to the reset input terminal R of the flip-flop 48 to clear the interrupt signal and enable reception of the next new noise signal, and at the same time, a noise processing program as shown in FIG. 3 is executed. Return to the original process control program execution state. Therefore, the occurrence of a down state of the microprocessor 12 is prevented.

Note that some process controllers are equipped with a watchdog timer. This watchdog timer has the function of transmitting a timeout signal to the outside to bring the device into a down state if a calculation or the like does not end within a predetermined time due to a failure of the microprocessor or the like. For such a configuration, by configuring the watchdog timer to stop operating only while the noise processing program is running and to operate when returning from the interrupt state, unnecessary timeout signals and downtime can be avoided. It is possible to avoid the situation.

Furthermore, since the noise processing program must be completed in a short time, the number of program steps must be minimized, and the hardware configuration must be simple and compatible with this requirement.

In addition, in actual use, even in conventional process controllers without noise filters, down conditions occur only once or twice a month, even under adverse conditions; In a microprocessor, the microprocessor executes an interrupt handling program less frequently, and therefore the process controller that normally does There is no problem in the execution of the control program.

(f) Effects As mentioned above, in the past, noise filters were installed in the input/output power lines to reduce intruding noise, or the input/output power lines were insulated at the expense of cost reduction, thereby achieving more complete noise isolation. However, in the present invention, the noise is more proactively utilized to prevent downtime caused by process controller noise. An interrupt state is generated for the microprocessor before the state occurs, and the interrupt processing program returns to the normal state from the abnormal state caused by noise before returning to the control program. This has an excellent effect in that no down state occurs and stable operation is possible.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a process controller according to an embodiment of the present invention, FIG. 2 is a configuration diagram of a noise detection section and an interrupt signal generation section, and FIG. 3 is a flowchart showing a noise processing execution program in an interrupt state of a microprocessor. It is. l...Process controller, 12 river microprocessor,
44a to 44d... Noise detection section, 48... Interrupt signal generation section.

Claims (1)

[Claims] (1) a noise detection unit that outputs a noise detection signal in response to a noise input that is equal to or higher than a predetermined threshold level;
A process characterized by comprising: an interrupt signal generation section that generates an interrupt signal in response to a noise detection signal from the noise detection section; and a microprocessor that executes a noise processing program in response to input of the interrupt signal. Controller.