JPH0219901A - Analog output method and device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an analog output method and device for a so-called programmable controller that automatically sets a sequence program applied to a process control system, for example. .

[Conventional technology]

Conventionally, in this type of control system, the analog output device':A
As a method for adjusting the offset, as shown in a conceptual block diagram in FIG. 3 (first conventional example), a part of the digital/analog conversion circuit 1 is provided with a
J variable resistance 2. By providing 6 variable resistors 3 for gain adjustment, and artificially monitoring the analog output Is',
These resistors were used to manually adjust the offset and gain of the analog output device output.

As a second prior art example, Japanese Patent Application Laid-Open No. 63-66606 describes a calibration method for a current output circuit used as a component of a process control system.

In this second conventional example, in a current output circuit that converts a digital input value into a current signal within a predetermined range and outputs the signal, the current output circuit is provided with means for digitally converting the output current signal, and a plurality of digital conversion values and the above-mentioned digital input value are A current output circuit calculates and stores correction data based on the relationship between the two, and when outputting current, gives the digital value obtained from the ideal digital human power value corresponding to the output value and the correction data as the digital human power value. This is a calibration method.

[Problem to be solved by the invention]

However, with the technique of the first conventional example, the adjustment takes time, and after the adjustment, the offset adjustment 6I variable resistor 2. There is a problem in that in most cases, the variable resistors 3 for gain adjustment are individually fixed, making it impossible to readjust them.

In addition, in the second conventional example, the correction data is obtained by a manual method in which commands are given sequentially from a machine interface, or it is described as a means that can be automatically performed by running a calibration program. , Specifically, as is clear from the flowchart showing the calculation procedure of the correction data in Figure 3, 0%
After the digital value output has elapsed for a predetermined time, the analog-to-digital conversion value is read and stored, and then after the 100% digital value output has elapsed for a predetermined time, the analog-to-digital conversion value is read and stored, and correction data A is obtained.

This is a method of storing B [Equation (4), Equation (5)],
The calculation method is complicated and the calculation time is relatively long.

SUMMARY OF THE INVENTION An object of the present invention is to provide an analog output adjustment method and apparatus thereof that overcomes the drawbacks of the conventional methods and has a high calculation speed and high accuracy.

[Means to solve the problem]

In order to solve the above problem, we eliminated the variable resistor and installed a D/A converter for adjustment separately from the output D/A converter.
A memory is provided to store the data to be given to the A controller data and the D/A controller data for this 'J8 adjustment, respectively.
The purpose is to cancel the error in the output D/A converter data with the adjusting D/A converter data, and the data given to the adjusting D/A converter data converts the output of the analog output device into a highly accurate one. Convert it to digital data with an analog human power device, compare the data output by itself with the data transmitted from the analog input device with an analog output device, and adjust the D/A so that this difference is minimized. This is the data given to the controller, and is programmed in software so that the data is written into memory.

[For production]

With the above configuration, when adjusting the analog output device before operation, one high-precision analog input device is prepared, the analog output of the analog output device is given to the analog input device, and the analog input device The analog value from the analog output device is sent to the process control system after being converted into a digital value through negative feedback and minimizing the difference from the digital input value of the analog output device. Gain and offset adjustments are automated with high accuracy.

〔Example〕

FIG. 1 shows a block diagram during adjustment in an embodiment of the present invention, and FIG. 2 shows a block diagram during operation when the analog output is sent to the process control system.

The modularized analog output device 4 has a C
A PU (central processing unit) is installed, and this CPU has memory (
(RAM, etc.) 11 and the input line from it are connected, and the output line from the CPU is also connected to the output D.
/A converter data rotor and the adjusting D/A converter data 10 are respectively connected. The analog outputs from these output D/A converter data 10 and adjustment D/A converter data 10 are respectively given to the output device 7, where the two analog outputs are added and the analog output of this analog output device 4 is It becomes 12.

The digital input to this analog output device 4 is provided by another CP.
It is given from the U module 9 as CPU module output data 9S' during adjustment.

The analog output 12 of the analog output device 4 is also received by an analog input device 8, where the analog data is sent to another CPU module 9 as digital data 8s.
connected to the input.

In this way, during adjustment, the digital data 5S given from the CPU 5 in the analog output device 4 to the output D/A converter becomes the analog output 6S, and is sent to the analog input module 8 via the output device 7. It is output as digital data 8S again, returns to the analog output device 4 via another CPU module 9, and is sent to the CPU 5.
, the digital data 5S and the returned digital data 8S are compared, and adjustment data 5S' that reduces the difference is given to the adjustment D/A converter 10, and the adjustment D/A controller The data 10 becomes an analog output 105 for adjustment, and is added to the analog output 6S of the output D/A converter data at the output device 7.

The above operation is repeated until the difference between the previous digital data 5S and the returned digital data 8S is minimized, and when the minimum adjustment data 5S' with the value that minimizes the difference is found, the minimum adjustment data 5S' is a memo IJII (e.g. E2ROM,
This series of operations is performed for all the data that the CPU 5 can command to the output D/A converter.

In this way, the analog output 12 of the analog output device 4
After the C is adjusted, the normal operation shown in Fig. 2 is performed, and another C
The CPU 5 reads the minimum adjustment data 11s from the memory 11, which is adjustment data corresponding to the operating CPU module output data 9S received from the PU module 9.
The CPU 5 gives the output digital data 5S to the output D/A converter 10, and outputs the adjusting D/A converter 10.
The minimum adjustment data 11S is given to .

The above two operations can be set in advance by switching the program with a switch (not shown), and it is only necessary to prepare the analog input device 8. For example, the analog output device 4 Readjustment is also possible at the location where the system is operating.

〔Effect of the invention〕

Thus, according to the present invention, the adjustment of the analog output device, which conventionally had to be done manually or by means that are cumbersome but time-consuming, can be done automatically and in a short time, and readjustment can be done at any time. Since the adjustment is performed for all analog output data, the accuracy is significantly improved, and the reliability of the operation of the process control system is greatly increased.

[Brief explanation of the drawing]

1 and 2 are block diagrams showing the circuit configuration and data flow during A timing and operation in one embodiment of the present invention, and FIG. 3 is an explanatory diagram of a conventional example. DESCRIPTION OF SYMBOLS 1... Digital/analog conversion circuit, 2... NJ variable resistor for offset adjustment, 3... Kawaguchi J variable resistor for gain adjustment, 4... Analog output device 4.5... CPU, 6
... Output D/A controller, 7... Output device, 8
...Analog input device, 9...Another CPU module, 10...D/A converter data for adjustment, 11...Memory, 12...Analog output. Negative -1 δ Co (Actual 71 Chii 1.8 Circulation B Exists) et al. Applicant's Representative Mr. Sato - Yu Figure 2 (Example, during operation) Display of Procedural Event Device Case 1988 Patent Application No. 170084 Name of the invention Relationship between analog output method and the device correction case Patent applicant (662) Anyo Electric Manufacturing Co., Ltd. Figure 3 (prior example)

Claims (1)

[Claims] 1. In an analog output device that sends an analog output to a process control system, the analog output is converted into a CP as a digital value.
U, the digital output data from this CPU is output as an analog output via the output D/A converter data, an analog output is generated from this analog output device via an output device, and an analog output from this analog output device is generated. is converted into digital data through an analog input device, and then returned to the previous CPU via another CPU, and this CPU
U compares it with the previous digital output data, calculates the difference, and sets the adjustment data that reduces the difference to D.
/A control data is used as an analog output for adjustment, and the output device adds it to the previous analog output to generate a new analog output of the analog output device.This operation is repeated to minimize the previous difference, and the minimum value is The minimum adjustment data that is the difference is stored, the output data from another CPU is given to the previous CPU, and the stored minimum adjustment data is read out along with the digital output data from that CPU and used as adjustment data. An analog output method characterized by adding an analog output for adjustment to an output device via a /A controller and sending the analog output from the output device to a process control system. 2. Adds the CPU that accepts the set digital value, the output D/A converter data that converts the digital output data from this CPU to analog output and provides it to the output device, and the analog output from the D/A converter data. an output device that sends out the analog output of the analog output device; another CPU that derives the set digital value; and an output device that takes the analog output from the previous output device and returns it as digital data to the other CPU. An analog input device, a memory that can calculate the difference between the returned digital data and the previous digital output data, store and read the minimum difference as the minimum adjustment data, and accept and adjust the previous difference as adjustment data. An analog output device characterized by comprising: an adjusting D/A converter for applying an analog output to the output device.