JPS641802B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a microprocessor-based controller. 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 in place of analog control calculation systems.
Moreover, microprocessor-based controllers use a single piece of hardware for single-loop control.
There is an advantage that various control calculations such as cascade control can be executed by a user program, and various auxiliary calculations can also be executed by a user program in addition to the control calculations. FIG. 1 functionally shows a conventional microprocessor-applied controller. In the figure, analog inputs E _i such as measured values from a process quantity detector (not shown) and temperature and pressure for temperature and pressure correction are A/D converted in an input processing unit 1 and input to an input register as a digital signal. Stored in X.
The data stored in the input register X is subjected to various calculations such as linearization, temperature and pressure correction, and filtering in the auxiliary calculation section 2, and is then given to the control calculation section 3 as a measured value PV. The control calculation unit 3 calculates the measured value PV
A PID calculation block 31 performs PID calculation on the deviation between SV and the set value SV, a limiter 32 limits the upper and lower limits of the output of the PID calculation block 31, and a control variable is determined by switching between the manual operation output MVM and the automatic operation output MVA. It is composed of an A/M switch 33 that outputs MV, inputs the measured value PV, and outputs the manipulated variable MV. The auxiliary calculation unit 2 and the control calculation unit 3 execute various calculations according to user programs. The manipulated variable MV from the control calculation section 3 is stored in the output register Y. In the output register Y, the stored data is D/A converted by the output processing unit 4 and becomes an analog signal E ₀
is output as In this way, in the past, functional blocks such as PID calculation blocks, limiters, manual/automatic switching devices, etc. required for control calculations were made into elements, each given a function number, and used as one command in a program. A control calculation section 3 that executes control calculations is assembled. Although this method can be used in various modifications as a control calculation unit, it has the disadvantage that a program cannot be assembled without detailed knowledge of control, that is, without accessing the internal structure of the controller. For example, even when configuring a controller with basic PID operation, you can change the operation mode related to set values (computer settings, cascade settings, local settings, etc.) and the operation mode related to manipulated output (automatic, manual, DDC, etc.) It is also necessary to change these operating modes in a balanceless and bumpless manner. Therefore, programs such as cascade control as shown in FIG. 2 have the disadvantage of being quite complex. The present invention realizes a microprocessor-applied controller that does not have the above-mentioned drawbacks by making the entire function of the control calculation section that inputs the measured value PV and outputs the manipulated variable MV into one block and functions it. It is. Fig. 3 is a block diagram showing an embodiment of the functional configuration of the controller of the present invention.The difference from the conventional example is that three standardized control functions BSC, CSC, and SSC are provided in the control calculation section 3. However, each control function can be selectively used with one command of the program. BSC is a single-loop control function,
As shown in FIG. 4, the functions necessary for single-loop control have been standardized. That is, the control element CE performs a predetermined control calculation on the deviation between the measured value PV and the set value SV, and controls and outputs the upper and lower limit values. Manual/automatic changeover switch SW ₁ switches between the output of CE and the output of manual actuator MR, and outputs the operation output MV.
shall be. The automatic operation mode and manual operation mode are switched by pressing push button A or M of the operation mode switching button SM. In order to perform this switching in a balanceless and bumpless manner, the operating output MV is given to the control element CE as a tracking signal. In addition, the measured value PV, set value SV, and manipulated output MV are displayed on the displays IM and OM, respectively.
Furthermore, the set value SV can be set externally using switch SW ₂ that switches between internal and external settings.
is provided, and SW ₂ is the operation mode switch button
By pressing pushbutton C on the SM, it switches to the external setting side. This setting value switching is also performed bumplessly. During internal setting, the SV can be changed using the set value change button SP. Further, various control operations such as PID operation, batched PID operation, and sampled value PI operation can be assigned to the control element CE of the BSC. Furthermore, an input compensation signal, an output compensation signal, a tracking signal, and a tracking contact signal can be applied to the CE from the outside.The input compensation signal can be used to program programs such as dead time control, and the output compensation signal can be used to program programs such as feed forward control. I can do it. CSC is a cascade control function, and the functions necessary for cascade control as shown in Fig. 5 are standardized. In other words, the control element on the primary side
CE ₁ performs specified control calculations on the deviation between measured value PV ₁ and set value SV ₁ , and outputs with limited upper and lower limits.
Set value SV ₂ to control element CE ₂ where MV ₁ is the secondary value
given as. CE ₂ performs a predetermined control calculation on the deviation between the measured values PV ₂ and SV ₂ and generates an output with upper and lower limits limited. This output becomes the manipulated output MV when in automatic operation mode. Manual and automatic balanceless/bumpless switching, display and setting of measured value PV ₁ , set value SV ₁ , and manipulated output MV.
Processing such as internal/external switching of SV ₁ is the same as the single loop control function BSC. In addition, the CSC is configured so that when the manipulated output MV is in the manual state, CE ₁ tracks the measured value PV ₂ on the secondary side using switch SW ₃ , and furthermore, the control parameters of CE ₂ on the secondary side can be entered using the keyboard. When tuning using , switch CE ₁ and CE ₂ .
SW ₄ is used to disconnect, and switch SW ₅ is used to track CE ₂ to the set value SV ₂ so that the output of CE ₁ is not saturated, and PV ₂ and SV ₂ are displayed on the display IM. Note that CE ₁ and CE ₂ are disconnected by a cascade open/close changeover switch CS.
When CS is set to the open side, a series of operations related to the separation of CE ₁ and CE ₂ described above are automatically performed. Furthermore, the control calculations executed by CE ₁ and CE ₂ are BSC
As in the case of , each of the various control operations can be specified, such as PID operation, batched PID operation, and sampled value PI operation. An input compensation signal and an output compensation signal can be applied to CE ₁ and CE ₂ from the outside, respectively, and a tracking input and a tracking contact input can be applied to CE ₂ from the outside. SSC is a selection control function, and as shown in FIG. 6, the functions necessary for selection control are standardized. That is, the outputs MV ₁ , MV ₂ of the two control elements CE 1 , CE ₂ and _the external inputs SL ₁ , SL ₂
Select one of the elements specified by the user.
It is the SE's choice. The selection element SE has maximum value selection mode, minimum value selection mode, MV ₁ selection mode, MV ₂ selection mode, SL ₁ selection mode, and SL ₂ selection mode. ) can be selected. SL ₁ and SL ₂ are given to the selection element SE via the buffers BF ₁ and BF ₂ , and the buffers BF ₁ and
BF ₂ has a control output for bumpless switching.
MV can be given as a tracking signal. MV is given to CE ₁ and CE ₂ as a tracking signal. The display IM shows the measured value of CE ₁ .
PV ₁ and set value SV ₁ are displayed, and the display OM displays the manipulated output MV. The set value SV ₁ of CE ₁ can be switched between internal and external using switch SW ₂ . Furthermore, input compensation signals and output compensation signals can be applied to CE ₁ and CE ₂ from the outside. Various control calculations can be specified for CE ₁ and CE ₂ as in the case of BSC and CSC. In this way, in the present invention, standardized single-loop control functions, cascade control functions, and selection control functions are prepared as control calculation units, and each control function is treated as one command of the program, so that a conventional analog controller can be selected. You can program intuitively. FIG. 7 is a block diagram showing one embodiment of the controller of the present invention, FIG. 8 is a front configuration diagram thereof, and FIG. 9 is a block diagram showing an embodiment of the controller of the present invention.
The figure is a configuration diagram of the side panel. In the figure, analog inputs E _i1 to E _i5 of temperature, pressure, etc. for measurement values and temperature/pressure correction are connected to input multiplexer 11.
are sequentially input to the A/D converter 12, converted into digital quantities, and sent to the microprocessor (hereinafter referred to as
(called the CPU) 13. On the other hand, digital inputs D _i1 to _{D i3} necessary for sequence processing or various operation switching, etc. are connected to the CPU 1 via a digital input interface 14 and a bus 15.
It is incorporated into 3. Communication with a host computer or an operator console is similarly performed via the communication interface 16. In addition, the indicators IM and OM on the front panel 17, the set value increase/decrease button SP,
Interface 1 with operating output increase/decrease lever MR
8, and a keyboard KY 1 on the side panel 19 for setting various control parameters, variable parameters, displaying input/output values, etc. KY ₁ Display DY ₁
The interface 20 and the like are also performed via the bus 15. The results of various calculations performed according to the programs stored in the memory section 21 are converted into analog outputs by the D/A converter 22, and then held in the output sample and hold circuit 23 until the next update time. Further, since the output of the controller is normally a current output for valve operation, one of the outputs of the sample and hold circuit 23 is outputted through the voltage/current converter 24. Various status outputs are output via the digital output interface 25. Timer 26 is the scanning period of calculation (0.2 seconds)
A clock using a crystal oscillator is used as the basic clock, and the clock is clocked every 0.2 seconds.
Issues a timer interrupt signal to the CPU. The watchdog timer 27 operates when the CPU does not operate normally due to a CPU error or program error.
When an abnormality is detected, a fail signal Fail is sent to the outside, and an indication is made on the LP ₁ provided on the front panel 17. And the CPU controls the input/output multiplexer,
Controls A/D conversion and D/A conversion, digital calculations, self-diagnosis, etc. of the memory section 21
RAM ₁ (random access memory) is a memory used for temporary storage of data, etc., and has several dedicated registers such as an input register, an output register, and a temporary storage register. Memory section 2
ROM ₁ (read-only memory) of No. 1 is a memory in which a system program is stored. The system program includes a management program for managing the operation of the entire controller, an input/output signal processing program, an arithmetic processing program, a data display program, a self-diagnosis program, and auxiliary arithmetic operations.
This is a fixed program consisting of a library of control calculations. ROM ₂ of the memory unit 21 is a memory in which user programs are stored.
The user program is a program in which auxiliary calculations, control calculations, necessary fixed calculation constants, display information, etc. are created for each job. Therefore, ROM ₂ is mounted on the board with a socket or the like so that it can be changed. The user program is stored in a programmer 28 connected to the bus 15 during programming.
Created by. The programmer 28 stores a program for managing programming operations.
ROM ₃ , RAM ₂ where user programs are temporarily stored, keyboard KY ₂ and display DY ₂
It has an interface with D&K. In the controller of the present invention configured as described above, all internal operations are performed under the control of the CPU, and the system program that defines the control contents is stored in the ROM ₁ . First, when the power is turned on, the peripheral circuits are initialized for a certain period of time. Next, the analog inputs E _i1 to _{E i5} are input to the input multiplexer 11.
A/D conversion is performed by sequentially selecting the selected data. Each A/D converted signal is normalized and stored in its own dedicated input register. On the other hand, digital inputs (contact signals) are also read and stored in a dedicated input register. Once all input information has been stored in the input registers, auxiliary and control operations are executed according to the user program by combining operation libraries such as arithmetic operations, logical operations, and dynamic operations in the system program. Ru. At this time, as shown in Figure 10, RAM ₁
Input registers (X ₁ to _{X 5} for analog input, P ₁ to _{P 8} for variable constants, D _i1 to D _i3 for digital input),
Fixed constant registers K ₁ to _{K 4} in ROM ₂ as well as CPU
Arithmetic registers S ₁ -S ₃ in RAM ₁ and temporary storage registers T ₁ -T ₄ in RAM 1 are used. The operation result (output signal) goes into the output register in RAM ₁ . As shown in FIG. 10, the output registers include analog output registers _Y1 to _Y4 and digital output register _D0 . The contents of the analog output registers are read out in order and A/D conversion is performed.
The results of each D/A conversion are output to the output hold circuit 23.
is given and held. The contents of the digital output register are also read out and output as a contact signal via the digital output interface 25. The above steps from input signal reading, calculation, and output are repeatedly executed every 0.2 seconds, resulting in a response that is almost the same as a conventional analog controller. During this time, the measured value PV stored in the input register and output register,
The set value SV and manipulated variable MV are displayed on the displays IM and OM on the front panel 17, and the measured value
PV, set value SV, manipulated variable MV, output limiter, and various parameters are selectively displayed on display DY ₁ on side panel 19. Instead of the conventional numerical codes, the displayed contents are displayed in characters that can be recognized at a glance, thereby greatly reducing the possibility of erroneous operation or misidentification and improving operability. The display characters used are abbreviations commonly used in the fields of measurement and control. In the example of FIG. 9, "PV" has a measured value of "01" and represents the control element CE ₁ on the primary side. In other words, the measured value on the primary side
PV ₁ is 100.0%. Next, a user program is made up of three types of instructions: an instruction to read inputs, constants, etc. (hereinafter referred to as the LOAD instruction), an instruction to execute an operation (hereinafter referred to as the FUNC instruction), and an instruction to output the operation result (hereinafter referred to as the STORE instruction). There are also auxiliary instructions that branch the program (hereinafter referred to as the GOTO instruction) and instructions that indicate the end of the program (hereinafter referred to as END
There is a command. The operation registers S ₁ to _{S 3} used for all operations by these main instructions function as follows.

[Table] That is, the LOAD instruction stores data such as inputs and constants in _S1 , and at the same time has a pushdown function that shifts the previously stored data to the next register. The FUNC instruction has a pop-up function that executes an operation using the data input to _S1 to _S3 , stores the result in _S1 , and carries forward the data not used in the operation. The STORE instruction causes the data in _S1 , which is the operation result, to be output to the output register or temporary storage register, but the contents of the operation registers _S1 to _S3 remain unchanged. All analog input/output, variable constants, etc. are stored as normalized data in dedicated registers, so all signals and information, including fixed constants and temporary memory data,
You can read and read at STORE. Also, for the FUNC instruction,
As shown in Figure 11, in addition to calculation functions such as four arithmetic operations, signal conversion, selectors, limiters, dynamics, condition judgment, and alarms, there are control functions such as single loop control functions, cascade control functions, and selection control functions. be. Therefore, in the control system represented by the instrumentation flowchart of FIG. 12, the calculation procedure is as shown in FIG. 13. Since the calculation result is always popped up in _S1 , the calculation can be continued immediately by simply loading the additional data required for the next calculation, and the program can be
There are two types: LOAD and FUNC instructions, making it extremely simple. In this way, the calculation procedure is LOAD,
Complex operations can be executed simply by combining the three types of instructions: FUNC and STORE, and LOAD,
The three types of instructions, FUNC and STORE, are easy to understand because they follow the physical operating procedure of a single conventional arithmetic unit, and can be used to convert instrumentation flowcharts, which are often written as signal flows, into programs. Easy to express (sometimes difficult to express using formulas such as FORTRAN or BASIC). Therefore, program creators do not need to have any knowledge of computer software, and can calculate process inputs and outputs using procedures comparable to those of an analog computing device while looking at the instrumentation flowchart. It only needs to be small enough to convert the code into instruction code, and tools using large computers such as general compilers and generators are not required. In other words, as shown in FIG.
8 to the controller bus 15, the programmer 28 is connected to the controller bus 15.
ROM ₃ , RAM ₂ where user programs are temporarily stored, keyboard KY ₂ and display DY ₂
can be configured with an interface and a keyboard
Control calculation functions BSC, CSC, on KY ₂
By providing a dedicated key that provides SSC, the control calculation function can be realized with one-touch key operation. Furthermore, as shown in FIG. 14, the keyboard KY ₂ is provided with dedicated keys for providing arithmetic functions, a read command key, an output command key, etc.
Therefore, it becomes possible to provide it to users with programming included. Therefore, the user can easily create a program without disclosing control know-how. Note that the condition judgment function is used for digital input/output.
It branches the program based on ON/OFF and analog signal level comparisons, and can be used in combination with the GOTO instruction to execute sequence operations. In addition, LP ₂ installed on the front of the controller is an abnormality display that lights up when the input signals E _i1 to _{E i5} exceed a level of -5% to 105% or when the A/D converter 12 becomes abnormal. It's a lamp.

[Brief explanation of the drawing]

1 and 2 are block diagrams functionally showing a conventional microprocessor-applied controller, FIG. 3 is a block diagram showing an embodiment of the functional configuration of the controller of the present invention, and FIG. Figure~6th
The figure is a block diagram showing the configuration of the control function which is the main part of the controller of the present invention, FIG. 7 is a block diagram showing one embodiment of the controller of the present invention, FIG. 8 is a front configuration diagram thereof, and FIG. 9 10 is a configuration diagram of a register according to the present invention, FIG. 11 is a list of arithmetic functions and control functions according to the present invention, and FIG. 12 is an example of a control system to which the controller of the present invention is applied. The instrumentation flowchart, Figure 13, is an example of the program.
FIG. 14 is a front panel view of the programmer used in the present invention. 1...Input processing unit, 2...Auxiliary calculation unit, 3...
Control calculation unit, 4...Output processing unit, BSC...Single loop control function, CSC...Cascade control function, SSC...Selection control function.

Claims (1)

[Claims] 1. A microprocessor and a memory section connected to the microprocessor via a bus, the memory section having a first ROM storing a system program and a second ROM storing a user program.
It has ROM and RAM for storing data,
The second ROM is replaceably connected by a socket and configured to execute operations in the system program stored in the first ROM in accordance with the user program stored in the second ROM. The controller has a single-loop control function that has a standardized function for performing single-loop control in the control calculation section in the system program, a cascade control function that has standardized functions for performing cascade control, and a selection control. In addition to providing a selection control function that standardizes the functions for
One instruction of the user program stored in the second ROM is provided with an instruction for selecting any one of the plurality of control functions, and one instruction of the user program that selects this control function A controller characterized in that a control calculation function is determined. 2 includes a microprocessor and a memory section connected to this microprocessor via a bus, the first ROM storing a system program in the memory section and the second ROM storing a user program.
It has ROM and RAM for storing data,
The second ROM is replaceably connected by a socket and configured to execute operations in the system program stored in the first ROM in accordance with the user program stored in the second ROM. The controller has a single-loop control function that has a standardized function for performing single-loop control in the control calculation section in the system program, a cascade control function that has standardized functions for performing cascade control, and a selection control. A selection control function is provided with standardized functions for the second control function.
The control calculation function is selected by one command of the user program stored in the ROM, and when creating the user program, one of the plurality of control functions is selected on the keyboard. A programmer having a single loop control function key, a cascade control function key, and a selection control function key as dedicated keys for the controller is connected to the microprocessor via the bus.