JPH0219482B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a programmable controller using a microprocessor, and more particularly to a controller in which auxiliary calculations and control calculations are performed by a user program programmed by a user.

<Prior Art> Recent processes require more precise control than ever before in terms of energy conservation, resource conservation, and pollution prevention. For this reason, in the field of process control as well, microprocessor-applied digital control calculation systems have been put into practical use as controllers, instead of analog control calculation systems.

Moreover, the microprocessor-based controller uses a single piece of hardware to perform PID calculations and batch processing.
Various control calculations such as PID calculations and sample value PI calculations can be executed by a user program created by the user, and there is an advantage that various auxiliary calculations can also be executed by the user program in addition to the control calculations.

FIG. 1 is a block diagram showing an example of a microprocessor-applied controller.

Measured values from a process quantity detector (not shown) and analog inputs Ei1 to Ei5 such as temperature and pressure for temperature and pressure correction are sequentially input to an A/D converter 2 by an input multiplexer 1. It is converted into a digital quantity and processed by a microprocessor (CPU).
3). On the other hand, digital inputs Di1 to Di3 necessary for sequence processing or various operation switching are taken into the CPU 3 via the digital input interface 4 and the bus 5.

Further, communication with a host computer or an operator console is similarly performed via the communication interface 6. In addition, there is a front panel interface 8 with the displays IM and OM on the front panel 7, set value increase/decrease button SP, operation output increase/decrease button MR, and operation mode switch button SM, and settings or input/output of various control parameters and variable parameters. An interface 10 with a keyboard/display device 9 for displaying values, etc. is also connected to the bus 5.

The results of various calculations performed using programs stored in the memory section 11 are converted into analog outputs by the D/A converter 12, and then held in the output sample and hold circuit 13 until the next update time. Also, since the output of the controller is usually a current output for operation of a valve (not shown),
One signal from the sample and hold circuit 13 is outputted through the voltage/current converter 14 .

Various status outputs are output via the digital output interface 15. CPU3
An abnormality is detected by the watchdog timer 16 and output as a fail signal Fail.

FIG. 2 is a block diagram functionally showing a microprocessor-applied controller having such a configuration.

In FIG. 2, inputs taken in via an A/D converter etc. are input to an input register 20 in the memory section.
is stored as a digital signal. At this time, input processing such as conversion to an internal data format is performed.
The data stored in the input register 20 is subjected to various calculations such as linearization, temperature correction, and filtering in the auxiliary calculation section 21, and is then given to the control calculation section 22 as a measured value PV.

The control calculation unit 22 performs a predetermined control calculation such as a PID calculation on the deviation between the measured value PV and the set value SV.
The auxiliary calculation section 21 and the control calculation section 22 execute various calculations according to user programs. The operation output MV from the control calculation unit 22 is stored in the output register 23. The data stored in the output register 23 is outputted via a D/A converter or the like.

Generally, a variety of calculation blocks necessary to configure the functions of the controller are prepared, and a function number is assigned to each of them, and these calculation blocks are sequentially assigned by function number using a user program created by the user. The configuration is such that by specifying the combination, a predetermined control operation is executed.

For example, when performing PID control calculations, the measured value
A PID calculation block that performs control calculations on the deviation between PV and set value SV, a limiter block that limits the upper and lower limits of the output of the PID calculation block, and the output of the limiter block and the output of the manual operation device are switched to obtain the manipulated output MV. Combinations of manual/automatic changeover switches, tracking processing for balanceless and bumpless switching between manual and automatic, processing associated with switching between internal and external settings, and processing related to display of PV, SV, and MV. is specified by the user program to perform the functions of the controller as a whole.

<Problems to be Solved by the Invention> In this way, conventional controllers configured by elementalizing various functions of control calculation into calculation blocks and combining these elements can be used in various modifications as a control calculation section, but on the other hand, the control The problem was that it was difficult to assemble the program without detailed knowledge of the program.

Therefore, the inventors proposed a controller as disclosed in ``Japanese Unexamined Patent Publication No. 13506/1983 (Japanese Patent Publication No. 1802/1983).

This controller has a single-loop control function that has standardized functions for single-loop control, a cascade control function that has standardized functions for cascade control, and a selection control function that has standardized functions for selective control. In addition, an instruction for selecting any one of these plurality of control functions by one instruction of the user program is provided, and one instruction of the user program for selecting a control function is provided for selecting one of these control functions. It is designed so that it can be determined.

By the way, in this case, for example, even in single-loop control, normal PID calculation, batched PID calculation,
There are sample value PI calculations, etc. Therefore, it is desirable to be able to easily make these selections while taking advantage of the advantage that programs can be assembled without detailed knowledge of control.

The present invention has been made in view of these points, and allows programming in the same way as selecting a conventional analog controller type, and also allows PID calculations and batched PID calculations as control calculations. The purpose of this invention is to provide a microprocessor-applied controller that can easily set calculations and PI calculations with sample values.

<Means for Solving the Problems> The present invention, which achieves the above-mentioned objects, has the following features: In a microprocessor-applied controller in which auxiliary calculations and control calculations are performed by a user program written by a user, a measured value PV is inputted, and a manipulated output MV is inputted. A control calculation function element that standardizes the entire control calculation function to be output as one control function, and a control calculation provided within this control calculation function element that performs a predetermined control calculation on the deviation signal between the measured value PV and the set value SV. A functional block that performs each process of PID calculation, batched PID calculation, and sample value PI calculation, which is provided as a function to perform separate control calculations within this control calculation element, and control calculation of this control calculation element. Function as mentioned above
A register that stores information on selecting PID calculation, batched PID calculation, or sampled value PI calculation; With
A functional block selection means for selecting a functional block that performs either PID calculation or sample value PI calculation.

<Operation> When assembling a program, the user specifies the control operation function with one instruction, and also sets information in the register to indicate whether to perform PID operation, batched PID operation, or sampled value PI operation. .

The control calculation function inputs the measured value PV, performs the specified control calculation operation based on the information set in the register, and outputs the calculation result.
Operates as a controller that outputs as MV.

<Embodiment> FIG. 3 is a functional block diagram showing an example of the control calculation section of the controller of the present invention.

In the figure, R1 to R4 are registers, R1 has the measured value PV, and R2 has the set value SV.
However, the operation output MV is stored in R3, and the information SS for selecting the control calculation function is stored in R4.

CF is a control calculation function element that standardizes the entire control calculation function that inputs the measured value PV and outputs the manipulated output MV as one control function, and this control function is selected by one command of the user program. be.

CE is provided within this control calculation function element CF, and is a control calculation element that performs a predetermined control calculation on the deviation signal between the measured value PV and the set value SV. Within this control calculation element CE, there are separately provided function blocks for performing various processes such as PID calculation, patched PID calculation, and sample value PI calculation as functions for performing various control calculations.

A switch means provided in front of the plurality of function blocks selects one of them based on the information stored in the register R4.

That is, for example, if the information stored in the register R4 is "0", the switch means is connected to the contact 1 side and selects the PID calculation function. Further, if the information stored in the register R4 is "1", the switch means is connected to the contact 2 side, and the PID with pin
When the calculation function is selected and the information is "2", the switch means is connected to the contact 3 side and the chimple value PI calculation function is selected.

LM is a limiter that controls the upper and lower limits of the output from the arithmetic function block CE. SW1 is an automatic/manual changeover switch that changes the output of the limiter LM and the output of the manual actuator MR to output the manipulated output MV.
That is.

Automatic operation mode A and manual operation mode M can be selected using the operation mode switching button provided on the front panel 7.
It can be switched by pressing A or M on SM.

In order to perform this switching in a balanceless and bumpless manner, during manual operation, the operation output MV is applied as a tracking signal to the control calculation function block CE by switch SW2.

Further, the measured value PV and set value SV are displayed on the display IM on the front panel 7, and the operation output MV is also displayed on the display OM. Furthermore, the set value SV is provided with a switch SW3 that switches between internal setting and external setting so that it can also be set externally.
The switch SW3 is switched to the external setting side by pressing the push button C of the operation mode switching button SM.

When setting internally, use the set value increase/decrease button SP to change the set value SV.
can be changed.

FIG. 4 is a flowchart showing the main operations performed by control function CF. The program for performing this operation has been standardized in advance, and can be specified with a single command in the user program created by the user.

The fact that it can be specified with a single instruction in the user program means, for example, that the programmer used when the user creates the program can specify this control function CF.
A special key is provided for specifying the item, and the item can be specified easily by operating that key.

The arithmetic function performed in this flow can be specified by information stored in the register 4.

<Effect> As explained in detail above, according to the present invention,
You can create a program that performs the entire operation in the same way as a conventional analog controller, and you can also easily specify the function blocks that perform PID calculation, batched PID calculation, and sample value PI calculation. .

[Brief explanation of drawings]

Figure 1 is a block diagram showing an example of the hardware of a microprocessor-based controller.
FIG. 3 is a block diagram showing the functional configuration of a conventional controller, FIG. 3 is a functional block diagram showing an example of the controller of the present invention, and FIG. 4 is a flowchart showing the main operations. 2...A/D converter, 3...Microprocessor, 5...Bus, 7...Front panel, 11...Memory unit, CF...Control calculation function, CE...
...Calculation element, IM, OM...Display, LM...
Limituta, SW1~SW3...Switch.

Claims (1)

[Claims] 1. In a microprocessor-applied controller in which auxiliary calculations and control calculations are performed by a user program assembled by the user, the entire control calculation function that inputs the measured value PV and outputs the manipulated output MV is integrated into a single controller. A control calculation function element CF that is standardized as a control function and configured so that the control function can be used with one command of the user program; A control calculation element CE that performs predetermined control calculations on signals; and a control calculation element CE that performs each process of PID calculation, batched PID calculation, and sample value PI calculation, each of which is provided as a function to perform separate control calculations. a functional block; and the control calculation function of the control calculation element.
A register R4 stores information on whether to select PID calculation, batched PID calculation, or sampled value PI calculation, and a PID function provided in the control calculation element CE based on the information stored in the register R4. Calculation,
1. A controller comprising function block selection means for selecting a function block that performs either batched PID calculation or sampled value PI calculation.