JPH01184501A - Digital controller - Google Patents

Abstract

PURPOSE:To perform the automatic calibration of an analog output device in an on-line operation by providing two or more analog output devices and one or more analog input devices capable of performing the read-back of the analog output signal of the output device. CONSTITUTION:A CPU3 is connected mutually to the analog input device 1, a ROM4, a RAM5, a digital output device 6, and a digital input device 7 via a system bus. Furthermore, the CPU3 is connected to first and second analog output devices 2A and 2B mutually. Also, first and second switching relays 9A and 9B are provided. Each of the output devices 2A and 2B outputs a digital signal outputted from the CPU3 from a D/A conversion circuit 22, an amplifier circuit 23, and an analog output circuit 24, to an external device via the first switching relay 9A, and to the analog input device 1 via the second switching relay 9B. Also, the switching of the said switching relays 9A and 9B is performed by the analog output device 6. In such a way, it is possible to perform the automatic calibration of the analog output signal.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a digital control device that can input and output analog signals, and in particular to a digital control device that can perform automatic calibration of analog output signals online while continuing control. It is related to the device.

[Conventional technology]

FIG.
In FIG. 91, (1) is an analog input device into which an analog signal is input from an external device (not shown) or an internal device described later; 2) is an analog output device that outputs an analog signal to an external device or the above-mentioned analog input device (1), and (3) is connected to these analog input device (r) and analog output device (2), and is connected to the digital control device. CPU, which is the control center
(4).

(5) is connected to this CPU (3), and the ROM and 0PU (3) each store a control program.
RAM for storing calculation results etc. by K, (6), (7
) are connected to 0PtJ(3), and are a digital input device to which a digital signal is input from an external device, and a digital output device to output a digital signal to the external device, respectively. The analog output device (2) is the CPU (3).
) K-connected D/A conversion circuit (22), this D/A
An amplifier circuit (23) connected to the output side of the conversion circuit (22)
), an analog output circuit (24) connected to the output side of this amplifier circuit (23), and an analog output circuit (24) connected to the output side of this amplifier circuit (23);
4) has a switch (25) inserted between the output side and the analog input device (10).

The conventional digital control device is configured as described above, and the analog output device (2) converts the digital signal outputted by the OPU (3) into an analog signal with the D/A conversion circuit (22), and converts the digital signal into an analog signal. Amplifying circuit (23)
After amplifying the signal, the signal is output from the analog output circuit (24) to an external device or to the analog input device (1) through the switch (25). In the control mode for controlling an external device, the output of the analog output circuit (24) is output to the external device, but if the calibration mode is commanded by operating a calibration command switch (not shown), for example, the switch (
25) is closed and the output of the analog output circuit (24) is output to the analog input device (1). Note that the switch (26) is opened and closed by the output of the digital output device (6).

Hereinafter, the operation of the conventional digital control device will be explained based on the flowchart of FIG. 4 showing the processing procedure of the CPU (3). When calibration is commanded by operating the calibration command switch (step SL), the digital control device enters the calibration mode, and the CPU (3) reads the ROM (4) or RA.
The low reference signal SLD and the high reference signal SHD stored in the M(5) are read out (step S2), and the required signals are sent to the digital output device (6) and the switch (26
) is closed (step 83). Reference signal 8L0.8
HD is the D/A conversion circuit (2) in the analog output device (2).
The signal is converted into an analog signal in step 2), amplified in an amplifier circuit (23), outputted from an analog output circuit (24), and outputted to the analog input device (1) through a switch (25). Let these analog output signals be SLA, SHA (step S4). This analog output signal is converted into a digital signal by the analog input device (1) and then sent to the RA.
M(5) Ic is stored (step 85). OPU
(3) reads this and corrects the error caused by the signal passing through the analog human input device (1) according to a preset arithmetic expression. The correction value 5LAI, 5tIA1 or RAM(6) &
C is stored (step 86).

This digital output device, in addition to the reference signals SLD, 8HD, idealizes these reference signals.

The signal 5LAS8HA that should be obtained on the output side when it is applied to the analog output device (2) that is used as the reference for tab calibration
8 is stored one after another, and the calibration data of the analog output device 61 (2) is calculated using the correction value and the calibration reference signal. This is an analog input device (L)
The signal 5LA1.5HA1 in which the error in the analog output device (2) has been removed but the error in the analog output device (2) is mixed, and the corresponding analog output device, the signals 5LAS and 5HAS with no error in the analog output device (2). For example, 5LA1-8LAS, SHA.

-8HAS, (SLAl-5)IAl) / (S
LAS-8RAS) is the calibration data.

The calibration data calculated in this way is stored in RAM (5)
K is stored (step 58) and the digital controller returns to control mode (step 89). This control mode
In the mode, the calibration value obtained as described above is used to calibrate each output through the analog output device (2). As a result, an analog output signal without any error in the analog output device (2) is outputted from the digital control device.

[Problem to be solved by the invention]

With conventional digital control equipment, during automatic calibration.

When switching the analog output signal to the calibration reference signal.

There is a problem that it may affect the process, so automatic calibration is performed online. 5. Only when the controlled system is stable, should the operator manually hold the control value and calibrate it.
Alternatively, there are problems in that the devices must be duplicated so that one device continues to control while the other device performs calibration.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a digital control device that can automatically calibrate analog output signals online while continuing control.

[Means to solve the problem]

The digital control device according to the present invention includes at least two analog output devices and at least one analog input device capable of read-packing the analog output signals for each analog output control signal, and outputs the analog output by the digital output device. K is used to switch the signal.

[Effect]

In this invention, while continuing control using one of the at least two analog output devices provided for each control signal, at least one analog output device is provided for each control signal.
Automatic calibration of the analog output signal is performed by outputting one reference signal and read-packing the reference signal through an analog input device.

〔Example〕

Hereinafter, FIG. 1, which shows a block diagram of an embodiment of the present invention, will be described in detail. As with the conventional device, 0
PU (3) is an analog input device (1).

ROM (4), RAM (5), digital output device (6).

and a digital input device (7) interconnected via a system path. The CPU further includes a first analog output device (2 people) and a second analog output device (2B).
Both are interconnected via a system path (8). The first switching relay (9A) is connected to the first analog output device (2
The second switching relay (9B) is connected between the second analog output device (2B) and the external device, but the second switching relay (9B)
Connected between the analog output device (2) or the second analog output device (2B) and the analog input device (1).

Each analog output device (2A), (2B) is a CPU
(3) is the digital signal output by /A conversion circuit (2
2) is converted into an analog signal, and this analog signal is amplified by an amplifier circuit (23) and then output to an analog output circuit (24).
) to an external device through the first switching relay (9A), and to an analog input device (
Output to 1). In the normal control mode for controlling an external device, both analog output circuits (24)K output the same value, and the first analog output device [(24)
A) is outputted to an external device through the first switching relay (9 people), and is outputted from the second analog output device (2B) to the analog input device (L) through the second switching relay (9B). In addition, switching between the first switching relay (9 people) and the second switching relay (9B) is performed using the digital output device ff1f.
It can be operated using the output of (tl).

Hereinafter, the operation of the digital control device of the present invention will be explained based on the flowchart of FIG. 2 showing the processing procedure of the CPU (3).

When a calibration command is input through the digital input device (7) (step S tO), the second switching relay (9B) is operated together with the digital output device to change the output of the first analog output device (two people). Analog input device (1)K
output (step all). After this.

The digital control device is in calibration mode, and the CPU (
3) is the second analog output device (2B) K for control output processing.
Control will continue. Also, C! PU(3
) is the same as the conventional device, K ROM (4) or RAM (
51m, the stored low reference signal SLD and high reference signal SHD are read out (step 82'). Reference signal SLD
.

The SHD is converted into an analog signal by the D/A conversion circuit (22) in the first analog output device (2 people), and then sent to the amplifier circuit (2 people).
3), outputs from the analog output circuit (24) and passes through the second switching relay (27) to the analog input device (
1). This analog output signal is 5LA0.
5HA0 (step 84).

This analog output signal is converted into a digital signal by the analog input device (1) and then stored in the RAM (5)K (step 86). OPU (3) continues to do this,
According to a preset arithmetic expression, errors caused by the signal passing through the analog input device (1) are corrected.

The difference obtained by this correction calculation is the correction value 8LA,
5HA1 is also stored in RAM(5)K (step 8
8).

This digital control device, in addition to the reference signals SLD, SHD, brings these reference signals into an ideal state.

In other words, the signal 5L that should be obtained when it is applied to the first analog output device (two people) that is used as a reference for calibration is the output Ilk.
AS, 5HA8 is stored, and the calibration data of the first analog output device (!A) is calculated using the correction value and the calibration reference signal (step 87).

This is a signal SLA, in which the error at the analog input device (1) has been removed, but the error at the first analog output device (2A) is mixed.

This is due to the comparison between 5HA1 and the corresponding signals 5LAS and 8HAS, which have no error at the corresponding first analog output device (two people).For example, SL person t-8LAS, 8H.
A, -8HAS, (SLAl-SHA,) / (S
LAS-8) (As) becomes the calibration data.

The calibration data calculated in this way is stored in RAM (5)
(step S8).

Next, the first switching relay (9A) is operated to output the output of the first analog output device (2A) to an external device, and the second switching relay (9B) is operated to perform the control calculation (step S279).甚)

In addition, in the control mode, the second analog output device (2B)
Calibration data is obtained using the same method and stored in RAM' (5). In this control mode, the calibration data obtained as described above is used to calibrate the data each time it is output through the first analog output device (two persons). This is K
The analog output signal with no error from the first analog output device (2A) must be output from the digital control device.
Become.

In the above description, there are two reference signals and two calibration reference signals each, but the number may be one or three or more as necessary. Further, such a reference signal and a calibration reference signal are determined in advance for each controlled system or process to which an analog output is given.

Alternatively, a timer can be used to automatically switch to calibration mode periodically or when a predetermined condition is met, for example, when the temperature change in the control path exceeds a predetermined value. It is also possible to configure the calibration to be performed completely automatically.

Moreover, since the analog output device is duplicated, -
Even if an abnormality occurs in one analog output circuit, Vcib and control can be continued by switching to the other analog output circuit, making it possible to improve system reliability without duplicating the entire system. .

[Effect of release]

As described above, the present invention includes at least two analog output devices and at least one analog input device capable of read-packing the analog output signals. , without interrupting control (automatic calibration of analog output devices can be performed online, and control can always be performed with +% accuracy, which has the effect of contributing to labor saving and high precision control) .

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention. Fig. 2 is a flowchart showing the processing procedure when calibrating the analog output device, Fig. 3 is a block diagram showing a conventional digital control device, and Fig. 4 shows the processing procedure when calibrating the analog output device in the conventional device. It is a flowchart figure. Figure Kj = (1) Analog input device, (2 people)
・・First analog output device, (2B) −・Second analog D
/ Output device, (3) "-' OPU, (4)
''' RAM, (5)...RAM, (6)...
Digital output device, (7)... digital input device,
(9A)...First switching relay, (9B)...Second switching relay. Note that in the drawings, the same reference numerals indicate the same or equivalent parts. Agent: Teru Wado, Figure 2, Figure 3, Figure 4 Amendment to Figure Proceedings July 12, 1988

Claims (1)

[Claims] (1) at least two analog output devices that convert a digital signal into an analog signal and output it; an analog input device that converts the input analog signal into a digital signal; and at least two analog input devices that convert the analog signal into a digital signal. a switching means connected between an output device and the analog input device; a means for generating a digital reference signal; a means for inputting the reference signal to the analog input device through the analog output device; and a means for inputting the reference signal to the analog input device. a means for correcting errors in the analog input device for the input signal and storing the correction value; and a means for correcting the error to be output from now when the reference signal is applied to a reference analog output device having characteristics to be used as a calibration standard. a calibration data calculation means for calculating calibration data for an actual analog output device using a reference value and the correction value; and an instruction to automatically generate the reference signal and automatically calculate the calibration data. and means for automatically calibrating a signal passing through the analog output device using the calibration data, wherein while one analog output device continues to control, the other analog output device can automatically calibrate on-line. A digital control device characterized by: