JPH0612590A - Analog signal input device - Google Patents

Abstract

PURPOSE:To smoothly take proper measures at the time of fault generation by reducing the burden of confirming the zero position and the span deviation in the analog signal input device and the soundness of the device. CONSTITUTION:In the input device which a multiplexer 4 successively switches and inputs plural analog signal inputs 1 and are converted into digital values by an A/D converter 5, beforehand the reference voltage signal from a reference voltage generating device 3 is converted into the digital signal to be stored in E<2>PROM 10 as the value for the zero point adjustment and for the span adjustment. In the idle intervals between the conversion and transmission for the normal signal input, a signal switching device 2 is switched and connected to the side of the reference voltage generating device 3, obtaining the value adjusted by means of the input adjustment value for the zero point adjustment and for the span adjustment held in the E<2>PROM 10. The level difference between the value and the initial value which is previously written in the E<2>PROM 10. When the difference is larger than the allowable range, the information is transmitted to a main computer 14, generating a warning of abnormality or the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an analog signal input device used in a monitoring / control system such as a plant control device using a computer, and more particularly to a method for confirming the soundness of its own function.

[0002]

2. Description of the Related Art An analog signal input device (analog signal input card) used in a monitoring / control system such as a plant control device using a computer is used as a component thereof.
Due to the use of operational amplifiers, resistors, capacitors, transistors, etc. that have errors or factors that change the physical properties over time, after adjusting the zero point and span of the signal before starting use, periodically thereafter. Therefore, for example, the time when equipment such as a plant is stopped is used, and after reconfirmation, readjustment is performed in some cases.

Conventionally, this adjustment work is performed at 0% and 1 at the signal input section for each input channel (each analog input point).
A signal such as a voltage of 00% is input by using, for example, a reference voltage generator, and a potentiometer for adjusting a zero point and a span provided for each input channel is operated.

[0004]

As described above, in the conventional analog signal input device, in order to confirm the presence or absence of the deviation of the zero point or the span, as a result, the work must be performed as described above, and the processing is performed. The plant monitoring and controlling apparatus having hundreds or thousands of signal points has a problem that enormous labor and time are required.

The present invention has been made to solve the above problems, and an object thereof is to set the zero point and the deviation of the span of each input signal line within its own range within the range permitted for the initially adjusted result. It is to save labor in the above-mentioned periodical confirmation work by automatically detecting whether or not it is present and providing a function to inform the outside when an abnormal state occurs.

[0006]

SUMMARY OF THE INVENTION The present invention, in an analog signal input device for switching and inputting analog input signals from a plurality of input points and converting them into digital values, specifies an adjustment mode for performing zero point adjustment and span adjustment. Adjustment mode designating means, input point designating means for designating an input point to be a target of zero point adjustment and span adjustment, and for zero point adjustment or span adjustment from the input point designated by the input point designating means in the adjustment mode. Input the input reference voltage signal and input the digital conversion value as the input adjustment value for zero adjustment or span adjustment for the corresponding input point, and from the built-in reference voltage generator during normal use. The obtained reference voltage signal is periodically switched between the external input signal and read, and the difference between the read value and the initial setting value is compared and judged. And determining means, characterized in that a transmitting means for transmitting the information when the difference by the determining means is determined to become larger than the allowable range upper computer.

[0007]

When the analog signal input device is started to be used, first, the adjustment mode designating means designates the adjustment mode for performing the zero point adjustment and the span adjustment, and the input point designating means selects the object of the zero point adjustment and the span adjustment. Specify an arbitrary input point.

When the adjustment mode is designated, the input adjustment value sampling means selectively inputs the reference voltage signal from the designated input point, converts the voltage signal into a digital signal, and inputs for zero point adjustment and span adjustment. Collect as an adjusted value. In this way, the input adjustment values for zero point adjustment and span adjustment for each channel are collected.

In normal use, first, an analog signal input from the outside is converted into a digital signal,
It is converted by using the input adjustment values for the zero point adjustment and the span adjustment, which have been sampled, and sent to a host computer or the like.

The reference voltage generator is switchably connected to the input signal circuit between the conversion and transmission operations, and the converted value is obtained using the input adjustment values for zero point adjustment and span adjustment. This value is compared with the initial value based on the input adjustment value collected previously. As a result of the comparison, when the difference becomes larger than the allowable range, the information is transmitted to the host computer or the like, and the occurrence of the abnormality is notified.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an analog signal input device (analog signal input card) according to an embodiment of the present invention. In the figure, 1 is an analog signal transmitted from the outside to this device through a connector or the like,
For example, signals of 32 points are input to the signal switch 2. Further, the reference voltage is input to the signal switch 2 from the reference voltage generator 3. The signal switch 2 has a processing logic 11
The analog signal 1 or the reference voltage from the built-in reference voltage generator 3 is selected in accordance with the instruction from and is input to the multiplexer 4.

The multiplexer 4 sequentially switches the input signal according to a control signal given from the microcomputer 6 described later via the processing logic 11 and outputs the input signal to the A / D (analog / digital) converter 5. This A /
The D converter 5 converts the analog signal sequentially selected by the multiplexer 2 into a digital signal and outputs it to the local bus 7.

The microcomputer 6 processes the input signal.
The signal switching unit 2, which is provided for speeding up
Performs input signal processing including control of the multiplexer 4,
A register buffer / bus controller for which the signal will be described later
La8, send to main computer 14 via computer bus 13
Perform processing, etc. Further, the microcomputer 6 is
Adjustment modes for zero adjustment and span adjustment are set.
The zero point or span adjustment processing depending on the operation
And the input adjustment value is stored in a memory, for example, E² PROM
Write to 10. Subsequently, the microcomputer 6
Signal mode switch 2 to reference voltage generator 3
Switched and connected, and sequentially selected by the multiplexer 4.
The reference signal is the above E² Input tone written in PROM10
Adjust using the set value, and as the initial value, E² PRO
Write to M10.

In the normal state, the microcomputer 6 is further provided with E ² Together perform correction calculation of the input signal level based on the adjustment value written in PROM10, it switches the signal switching device 2 to the reference voltage generator 3 side, E ² PROM
Based on the adjustment value written in 10, the result of correction calculation of this signal and E ² The initial value written in the PROM 10 is compared. As a result of this comparison, if the difference exceeds the allowable value, processing such as sending this information to the main computer 14 via the computer bus 13 is performed.

Reference numeral 7 is a local bus for constructing a microcomputer circuit on this apparatus, and 8 is a register buffer / bus controller for interfacing between the local bus 7 on this apparatus and the computer bus 13.
Reference numeral 9 is a program for the microcomputer 6 to perform various arithmetic control processes, and further ROM (read-only memory) in which parameter data is stored in advance. 10 is a memory for storing the adjustment value and the reference value for comparison. E
² PROM (Programmable RO that can be electrically erased
M). Reference numeral 11 is a processing logic configured by hardware such as a logic IC.

The processing logic 11 is based on the state of a signal line 12 for transmitting a signal transferred from the microcomputer 6 through the local bus 7 and an operation content of a key input device (not shown) such as a keyboard. In addition, it is for performing necessary processing. The key input device is provided with, for example, adjustment mode designating means for designating a mode for performing zero point adjustment and span adjustment, input point designating means for designating an arbitrary input point to be a target of zero point adjustment and span adjustment, and the like. ing.

This analog signal input device is a computer bus 1.
3 is connected to the main computer 14. The computer bus 13 is for exchanging signals with the main computer 14, and the main computer 14 performs main arithmetic processing of the supervisory control system.

Next, the operation of the above embodiment will be described. When using the analog signal input device, first, the adjustment mode designating means of the key input device designates the adjustment mode for performing the zero point adjustment and the span adjustment, and the input point designating means becomes the target of the zero point adjustment and the span adjustment. Specify an arbitrary input point.

When the adjustment mode is designated, the microcomputer 6 switches the signal switch 2 to the side of the reference voltage generator 3 and adjusts the zero point or the span to the designated input point designated by the input point designating means. Input the reference voltage signal of. That is, the microcomputer 6 controls the multiplexer 4 for switching the input point to selectively input the reference voltage signal from the designated input point from the reference voltage generator 3, and the reference voltage signal to the A / D converter 5. A / D
Converted and taken as an input adjustment value for adjusting and span adjustment zero, E ² It writes in PROM10 corresponding to an input point. In this way E ² Input adjustment values for zero point adjustment and span adjustment for each channel are collected in the PROM 10.

Following this, the microcomputer 6
The reference voltage signal from the reference voltage generator 3 is sequentially read by the multiplexer 4, and the above E ² The PROM 10 is adjusted using the input adjustment values for zero point adjustment and span adjustment that have been sampled, and E ² is used as the initial value. Write to PROM10. The initial value is E ² as described above. After writing to the PROM 10, it switches to the normal operation mode.

In this normal use, first, the analog signal 1 input from the outside is sequentially selected by the multiplexer 4 and A / D converted by the A / D converter 5,
E ² above Correction calculation processing is performed using the input adjustment values for zero point adjustment and span adjustment collected in the PROM 10, the input signal level is adjusted, and the result is sent to the host main computer 14.

The microcomputer 6 uses the signal switch 2 to switch the reference voltage generator 3 between the conversion and transmission operations.
Is connected to the input signal circuit at a predetermined cycle, and E ² PR
The value adjusted using the input adjustment values for zero adjustment and span adjustment held in the OM10 is obtained, and this value and E ² The level difference is compared with the initial value written in the PROM 10. If the result of this comparison is that the difference is larger than the allowable range, the information is transferred to the upper main computer 1
4 and use it for necessary treatment, such as issuing an alarm.

This comparison function does not necessarily have to be performed at a high cycle, and may be determined by a balance of the signal acquisition cycle required by the application, the capability of the hardware used, and the like.

In the above embodiment, the case where only one analog signal input device is connected to the computer bus 13 has been described, but generally, a plurality of analog signal input devices are connected to the computer bus 13. Often, a system for inputting analog signals reaching hundreds of points is constructed.

[0025]

As described above in detail, according to the present invention, it is possible to confirm the deviation of the zero point or the span in the analog signal input device, which has been conventionally performed regularly, and to confirm the soundness of the device. It is possible to save labor and obtain an effect that appropriate measures can be promptly taken when a failure occurs.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an analog signal input device according to an embodiment of the invention.

[Explanation of symbols]

1 ... Analog signal input, 2 ... Signal switcher, 3 ... Reference voltage generator, 4 ... Multiplexer, 5 ... A / D converter,
6 ... Microcomputer, 7 ... Local bus, 8 ... Register buffer / bus controller, 9 ... ROM, 10
… E ² PROM, 11 ... Processing logic, 12 ... Signal line,
13 ... Computer bus, 14 ... Main computer.

Claims (1)

[Claims] 1. An analog signal input device for switching and inputting analog input signals from a plurality of input points and converting into digital values, an adjustment mode specifying means for specifying an adjustment mode for performing zero point adjustment and span adjustment, and a zero point. Input point designating means for designating an input point for adjustment and span adjustment, and in the adjustment mode, input a reference voltage signal for zero point adjustment or span adjustment from the input point designated by the input point designating means, Input adjustment sampling means for sampling the digital conversion value as an input adjustment value for zero adjustment or span adjustment for the corresponding input point, and externally inputting the reference voltage signal obtained from the built-in reference voltage generator during normal use. A determination means for periodically determining the difference between the read value and the initially set value by switching the signal and reading the signal, Analog signal input apparatus characterized by comprising a transmitting means for transmitting the information to the host computer when the difference is determined to become larger than the allowable range by.