JPH0216601A - Automatic/manual controller - Google Patents

Abstract

PURPOSE:To obtain an automatic/manual controller with a high reliability by detecting a voltage level change at the time of pressing a switch and at the time of reset, and when both level changes are detected, judging that the switching pressing is obtained. CONSTITUTION:A signal added to an input port 11 is changed to a low level only by a pressing time Tp with the pressing of an automatic or manual button 4 or 5. A reading means 6 of a processor MP reads by a prescribed timing, a detecting means 7 detects the level change at the time of the pressing and at the time of reset, and both level changes continue for a constant time (t), the pressing and the reset are judged. When a signal MV is fetched from a manual control means 2, the processor MP digitally holds through a multiplexer MPX, a control signal is outputted through a D/A converter and a holding circuit 91, and while the instruction of an instructing means 93 is watched, the manual control is executed. At the time of the MP trouble, a switch 80 selects the signal MV and is outputted through a voltage current converting circuit 92 to a process. Since the level change does not occur when the button 5 is troubled, the mode switching instruction is not executed. By the constitution, the erroneous operation due to the switch trouble can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an automatic/manual controller for controlling process variables such as temperature and flow rate.
The present invention relates to an automatic/manual controller having a manual adjustment means, and configured to switch between an automatic adjustment mode by the automatic adjustment means and a manual adjustment mode by the manual adjustment means by a signal from an automatic/manual changeover switch.

(Prior Art) Many controllers that control process quantities are equipped with manual adjustment means so that the process can be controlled manually in the event of a failure of the controller, startup, etc. The controller is provided with an automatic/manual changeover switch for switching between an automatic adjustment mode by the automatic adjustment means and a manual adjustment mode by the manual adjustment means.

Conventionally, such automatic/manual changeover switches have used manually driven on/off switch means.

(Problem to be solved by the invention) However, as this automatic/manual changeover switch,
When a manually driven on/off switch is used, if for some reason the switch fails while in the on state, the operating mode may change and a serious accident may occur.

For example, in manual adjustment mode, if a failure occurs while the automatic mode selection switch is on, the operation mode switches from manual adjustment mode to automatic adjustment mode, and a different signal that is not manually controlled is output to the process. occurs.

The present invention has been made in view of these points, and its purpose is to realize a highly reliable automatic/manual controller that prevents a failure of the automatic/manual changeover switch from leading to a serious accident. be.

(Means for Solving the Problem) FIG. 1 is a block diagram showing the basic configuration of the present invention. In FIG. 6, 1 is an automatic adjustment means, 2 is a manual adjustment means, and 3 is a process automatic adjustment means. 1 Manual adjustment means 2
controlled by

4 is an automatic mode selection switch for specifying automatic mode that outputs a signal that changes the voltage level by pressing the push button, and 5 is a manual mode selection switch that outputs a signal that changes the voltage level by pressing the push button. A mode selection switch, 6 is a signal reading means for reading the signal from the automatic mode selection switch 4 and a signal from the manual mode selection switch 5 for specifying manual mode at a constant cycle, and 7 is a signal reading means for reading the signal from the signal reading means 6. 8 is a level change detection means for detecting that a high level to a low level or from a low level to a high level continues for a certain period of time or more, and then from a low level to a high level or from a high level to a low level for a certain period of time or more; Upon receiving the output signal from the change detection means 7, the automatic mode selection switch determines which of the manual mode selection switch is pressed, and switches between the automatic adjustment mode by the automatic adjustment means and the manual adjustment mode by the manual adjustment means. This is mode switching means.

(Function) The level change detection means 7 detects the level change obtained when the switch is pressed and the level change that occurs when the switch returns, and when both level changes are detected,
It is determined that the corresponding switch has been pressed.

(Example) Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a block diagram showing an embodiment of the present invention. In FIG. 0, MP is a microprocessor, and in FIG.
In this microprocessor MP, which performs the functions of the level change detection means 7 and the mode switching means 8, 10 is an arithmetic control section, 11 is an input port for inputting signals from the automatic mode selection switch 4 and the manual mode selection switch 5;
12 is a ROM that stores various programs; 13 is a RAM that stores various data and calculation constants; 14 is a timer; and 15 is an output port from which control signals for controlling internal circuits are output.

Automatic mode selection switch 4, manual mode selection switch 5
are comprised of push-button switches, each of which has one end connected to a DC power source Vc, c via a resistor r.

MPX is a process signal pv from a process not shown.
, a multiplexer that selects the setting signal (target value) S, and the manual adjustment signal MV from the manual adjustment means 2. CMP is a comparator that receives the signal selected by the multiplexer MPX as one input, and its output is sent to the microprocessor MP. is applied to the calculation control section 10 of.

DA is a D/A converter that converts the digital signal from the microprocessor MP into an analog signal, 91 is a signal holding means that samples and holds the analog signal from the D/A converter DA, and outputs it to the process side. A voltage/current conversion circuit receives a signal from either the D/A converter DA or the manual adjustment means 2 via a switch 80. 9
3 is an indicator that monitors the signal output to the process.

The operation of the device configured in this way will be described next.

First, the operator presses either the automatic mode selection switch 4 or the manual mode selection switch 5 to specify the operating mode. For example, when specifying the manual adjustment mode, the operator presses the push button of the selection switch 5.

FIG. 3(a) is a waveform diagram showing changes in the output voltage when the push button is pressed and the switch is operating normally. When the push button is pressed as shown in the figure, the signal applied to the input port 11 changes from high level to low level by the time Tp that the push button is pressed.

The signal reading means 6 in the microprocessor MP reads the signals changing in this way at the timing shown in (b).

The level change detection means 7 detects the level change (change from high level to low level or change from low level to high level) obtained when the push button is pressed and the level change (low level change) that occurs when the push button returns. switch 5 that selects the manual adjustment mode when it detects that both level changes continue for a certain period of time or more. is determined to have been pressed. When it is determined that the switch 5 for selecting the manual adjustment mode has been pressed, the mode switching means 8 is notified of this, and the microprocessor MP operates in the manual adjustment mode.

In this manual adjustment mode, the microprocessor MP takes in the manual adjustment signal MV from the manual adjustment means 2 via the multiplexer MPX and digitally holds it in preparation for bumpless switching from manual adjustment mode to automatic adjustment mode. At the same time, the D/A converter DA and the signal holding circuit 9
1 outputs a manual adjustment signal by manual adjustment means 2 to the process. Since the magnitude of the manual operation signal output to the process is instructed by the instruction means 93, manual adjustment can be performed by operating the manual adjustment means while observing this instruction.

In this embodiment, if the microprocessor MP fails, the switch 80 selects the manual adjustment signal MV from the manual adjustment means 2 and outputs it to the process via the voltage/current conversion circuit 92. It is composed of

On the other hand, if the push button of the selection switch 5 is pressed and the push button remains in the on state as shown in FIG. The level will remain the same. In this case,
Since the level change detection means 7 does not detect the level change (change from low level to high level) that occurs when the push button returns, it determines that the switch 5 for selecting the manual adjustment mode has not been pressed normally, Do not instruct mode switching.

FIG. 4 is a flowchart outlining the above operations when the mode selection switch is pressed. In this flowchart, when it is determined in step 4 that the switch 4 for selecting the automatic adjustment mode has been pressed, the microprocessor MP operates in the automatic adjustment mode.

In this automatic adjustment mode, the microprocessor MP:
The process signal Pv and setting signal SV are converted into digital signals by a loop of comparator CMP, microprocessor MP, and D/A converter DA, and proportional and integral calculations are performed, for example, and the calculation results are converted to D/A. It is output to the process via the converter DA and the analog signal holding circuit 91. Also, D/
The calculation result from the A converter DA is output to the process via the switch means 80 and the voltage/current conversion circuit 92.

The operation of such an automatic adjustment mode is no different from that of conventionally known controllers.

In addition, in the above embodiment, the case where two selection switches of automatic adjustment mode and manual adjustment mode were provided was explained. can also be applied.

Further, in the above embodiment, the manual operation signal of the manual adjustment means 2 is outputted via the microprocessor MP, but it may be configured such that it is outputted directly to the process without passing through the microprocessor MP.

(Effects of the Invention) As explained in detail above, according to the present invention, it is possible to prevent incorrect operation due to failure of the switch means for specifying the operation mode, and highly reliable adjustment is possible. can be realized.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the basic configuration of the present invention, Figure 2 is a block diagram showing the basic configuration of the present invention.
The figure is a configuration block diagram showing one embodiment of the present invention, FIG. 3 is an operation waveform diagram showing the operation when the selection switch is operated,
FIG. 4 is a flowchart showing an example of the operation. 1...Automatic adjustment means 2...Manual adjustment means 3...Process 4...Automatic adjustment mode selection switch 5...Manual adjustment mode selection switch 6...Signal reading means 7...Level change Detection means 8...Mode switching means MP...Microprocessor DA...D/A converter CMP...Comparator FIG.

Claims (1)

[Scope of Claims] The device has an automatic adjustment means and a manual adjustment means, and is configured to switch between an automatic adjustment mode by the automatic adjustment means and a manual adjustment mode by the manual adjustment means by a signal from an automatic/manual changeover switch. The automatic mode selection switch outputs a signal that changes the voltage level when the push button is pressed, and the manual mode selection switch outputs a signal that changes the voltage level when the push button is pressed. a manual mode selection switch for specifying a mode; a signal reading means for reading a signal from the automatic mode selection switch and a signal from the manual mode selection switch for specifying the manual mode at a constant cycle; and a signal reading means for reading the signal from the signal reading means. Level change detection means for detecting that the level continues from high level to low level or from low level to high level for more than a certain period of time, and then from low level to high level or from high level to low level for more than a certain period of time; Upon receiving the output signal of the level change detection means, it is determined whether the automatic mode selection switch or the manual mode selection switch is pressed, and the switching is made between automatic adjustment mode by the automatic adjustment means and manual adjustment mode by the manual adjustment means. An automatic/manual controller characterized by being provided with mode switching means.