JPS6326883B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides positional PID (proportional and
This relates to a process controller that outputs calculation output (integral/differentiation).More specifically, it is configured to include a microprocessor, samples a process variable signal, converts it into a digital quantity, and adds P, I to the digital signal. This invention relates to a process controller for controlling a process by performing one or all of the arithmetic operations, .

[Conventional technology]

In the instrumentation of conventional analog devices, in order to configure an intermittent controller, which performs control for a certain period of time, holds the control output for the next certain period of time, and repeats this as one cycle, it is necessary to make adjustments for it. I had to prepare a meter. In addition, override control is a selection control that uses two controllers to select and output the larger or smaller control output.
To configure a controller, two or more controllers and selectors must be prepared, and the controllers must be of a type that can feed back the selected output to the outside.

[Problem that the invention seeks to solve]

In other words, in order to realize the two types of controllers, intermittent type and override type, for analog equipment, it was necessary to prepare dedicated equipment.
Therefore, the structure is complicated and uneconomical.

In contrast, recently, by using computers, especially microcomputers, it has become easier to form various types of controllers than by using the above-mentioned analog devices.

But it is normal PID (proportional-integral-derivative)
Arithmetic expressions, sample (intermittent type) PID arithmetic expressions, etc. are prepared separately as software packages, which has the disadvantage of requiring a huge amount of memory to accommodate each case. are doing.

[Means for solving problems]

In the process controller of the present invention, a remote target value is given to a calculation package that is assembled according to a calculation program stored in a ROM.
the second input terminal to which the process variable signal is applied
a third input terminal to which a position type control signal applied to the operating device is applied, and a fourth input terminal to which a flag type signal is applied;
When the flag type signal "ON" is given to the input terminal of In addition to outputting the current position type control signal, if a flag type signal "off" is given, velocity type proportional, integral, and differential calculations are performed on the deviation, and this calculated value is used as the previous internal position type. The control output values are added together and output as the current position type control signal.

[Effect]

An arithmetic package that performs normal proportional, integral, and differential calculations when the flag signal is "off" can perform the necessary operations as an intermittent controller or override controller, that is, differential calculations, by simply turning the flag signal "on." , the previous position type control output value is taken in from the outside, the current speed type proportional and integral calculation values are added to that value, and the operation automatically shifts to outputting the added value.

〔Example〕

FIG. 1 is a block diagram showing one embodiment of the present invention.

In the figure, PID is a device that performs all calculation processing of proportional, integral, and differential, and has one output terminal OUT,
It is composed of a PID calculation package having first to fourth input terminals H ₁ , H ₂ , P ₁ , and P ₂ , and this PID calculation package is assembled according to a calculation program stored in a ROM. The output terminal OUT delivers a position-type control signal, and the first input terminal _H1 is provided with a remote setpoint value. Second input terminal
H ₂ is supplied with a process variable signal, the third input terminal P ₁ is supplied with a position-type control signal applied to the operating device, and the fourth input terminal P ₂ is supplied with a flag-type signal. . RSP is the external setting value given to the first input terminal _H1 , and PV is the second
The process variable, LSP, given to the input terminal H _{2 of}
is a locally changeable setting value, CN is an output terminal
The control output (position type control output) obtained at OUT, FLAG, is a flag type signal applied to the fourth input terminal _P2 . Note that CO indicates the previous internal position type output value (previous internal position type control output value).

The figure shows a flag type signal at the fourth input terminal _P2 .
It shows the state when FLAG “off” is given, and in this case, the set value SP and the process variable
Perform velocity type proportional (P), integral (I), and differential (D) calculations on the PV difference output (control deviation) EN, and add the previous internal position type control output value CO to this calculated value △CN. outputs the control signal CN for the current position type.
Output to OUT. In the figure, CN ₁ is the previous internal position type output value (previous internal position type control output value) that is added to the control output change △CN.
This is the internal previous value corresponding to CO.

On the other hand, when the flag type signal FLAG "ON" is applied to the fourth input terminal _P2 , velocity type proportional (P) and integral (I) calculations are performed on the above-mentioned deviation, and the calculated value is △CN to third input terminal P ₁
The position type control signal CN ₁ given to is added to output the current position type control signal CN to the output terminal OUT. The state in this case is shown in FIG.

In Figure 2, PI is a proportional/integral block that takes the difference output (control deviation) EN between the set value SP and the process variable PV as input and performs predetermined proportional/integral calculations, and its output is the control output change △CN.
is obtained. Then, the output obtained by adding only CN ₁ ′, that is, the position type control signal CN ₁ from the third input terminal P ₁ to this control output change ΔCN is,
Control output CN (positional control output) is obtained as a positional control signal at the output terminal OUT.

Such a configuration is actually realized by an arithmetic program as shown in the flowchart of FIG.

In Fig. 3, depending on whether the control mode is the cascade () mode or not (step
101), the internal local target value LSP and the second
The process variable signal PV applied to the input terminal H2 _of
(Step 102), and in the case of cascade mode, the deviation between the remote target value RSP given to the first input terminal _H1 and the process variable signal PV (Step 103) is determined as the control deviation EN. . Next, depending on whether the flag type signal input to terminal _P2 is on or off (step 104), if it is off, P-I-D calculation is executed to obtain △CN. CN′ = CN as internal previous value
(Steps 105 and 106), and if it is on, jump the D operation block and execute only the P and I operation blocks to find △CN, and then set _CN1 of terminal _P1 .
Find CN with CN'1 as CN′ ₁ (steps 107 and 108).

Therefore, when the process controller of this embodiment is used as a normal controller, it is sufficient to turn off the flag type input signal.

On the other hand, when you want to take in the previous value output from the outside, if you turn on the shape signal FLAG applied to the fourth input terminal P ₂ , the differential D operation is automatically canceled and the current calculation is applied to the external input. (speed type)
Since the control output change amount ΔCN is added and output, it can be used as an intermittent controller and an override controller.

FIG. 4 is a block diagram showing an embodiment in which the present invention is applied to an intermittent controller. In Figure 4, the same symbols as in Figures 1 and 2 indicate corresponding parts, and SH is the PID calculation package PID.
This is a sampling and holding circuit that samples the output of the output signal using a timing pulse TP as shown in the figure and then holds the output.

In the process controller configured in this way, the PID calculation package PID is connected to the first input terminal H ₁
Input the set value SP given to the input terminal H2 and the process variable PV given to the second input terminal _H2 , and also input the previous output value _CN1 given from the outside to the third input terminal _P1 and the fourth output value CN1 given to the third input terminal P1. The flag type signal FLAG (on) given to input terminal _P2 is input, and the specified
After PID (proportional, integral, differential) calculation is performed, the output is sampled by a timing pulse TP as shown in the figure and held by a sampling and holding circuit SH. The output of this sampling hold circuit S/H is automatic mode A.
and manual mode M by the mode changeover switch, and a desired position type control signal is obtained at the output terminal OUT. At the same time, the output of the mode changeover switch is applied to the third input terminal _P1 as the previous output value _CN1 .

FIG. 5 is a block diagram showing an embodiment in which the present invention is applied to an override controller. In FIG. 5, the same numbers as in FIG. 4 indicate corresponding parts, and PID ₁ is the set value SP ₁ given to the first input terminal H ₁ and the process variable PV ₁ given to the second input terminal H ₂ . In addition, the previous output value CN ₁ from the outside applied to the third input terminal P ₁ and the flag type signal FLAG (ON) applied to the fourth input terminal P ₂ are input. The first PID calculation package performs PID (proportional, integral, differential) calculations, PID ₂ is the set value SP ₂ given to the first input terminal H ₁ and the process variable PV given to the second input terminal H ₂ . ₂ is input, and the previous output value CN ₁ from the outside is applied to the third input terminal P ₁ and a flag type signal is applied to the fourth input terminal P ₂ .
FLAG (on) is input, and the specified PID (proportional/
The second PID calculation package, SEL, which performs integral/differential calculations, receives the output of the first PID calculation package PID ₁ and the output of the second PID calculation package PID ₂ , and selects the larger output. It is a selector.

In this way, two PID calculation packages PID ₁ and PID ₂ are used, and the high selector SEL selects and outputs the larger control output. In the embodiment shown in FIG. 5, the case where the high selector SEL is used to select and output the larger control output has been described as an example, but the present invention is not limited to this. Of course, it is possible to use a low selector to select and output the smaller control output.

〔Effect of the invention〕

As explained above, according to the present invention, the processor is configured to include a microprocessor, samples a process variable signal, converts it into a digital quantity, and performs one or all of proportional, integral, and differential operations on the digital signal. The device that performs calculation processing can be easily operated as an intermittent controller or an override controller depending on the presence or absence of a flag signal, making it easy to handle and requiring special controller calculation means within the process controller. Since the number of software packages does not increase, the cost is low and it is economically effective. moreover,
When the flag type signal is on, it is automatically (forced) D (differential) - OFF (erased), which eliminates control errors and improves safety. Depending on how it is used, the flag type signal By simply connecting an external contact to the fourth input terminal, which is fed with , the PID/PI controller can be switched easily and instantaneously, so the practical effect is extremely large.

Further, according to the present invention, it is possible to minimize the increase in program memory, and also to
It is also extremely effective in that it can be easily used as an override controller.

[Brief explanation of drawings]

1 and 2 are block diagrams showing one embodiment of the present invention, FIG. 3 is a flowchart for explaining its operation, and FIG. 4 is an embodiment in which the present invention is applied to an intermittent controller. FIG. 5 is a block diagram showing an embodiment in which the present invention is applied to an override controller. H ₁ ...First input terminal, _H2 ...Second input terminal, P1...Third input terminal, _P2 ...Fourth input terminal, _OUT ...Output terminal, PI...Proportional・Integral block, PID...Proportional/integration/differential calculation package, RSP...External target value, LSP...Target value that can be changed locally, SP...Set value, PV...
...Process variable, CN...Control output (position type control output), △CN...Control output change (velocity type control output), CN ₁
...Previous control output value (position type control output).

Claims (1)

[Claims] 1 Consists of a microprocessor that samples the process variable signal, converts it into a digital quantity, performs one or all of proportional, integral, and differential calculations on the digital signal, and then transmits the calculation result to the operating device. In a process controller for controlling a process by giving a signal to , has a second input terminal to which a process variable signal is applied, a third input terminal to which a position type control signal applied to the operating device is applied, and a fourth input terminal to which a flag type signal is applied. It is composed of a proportional, integral, and differential calculation package, and this calculation package is assembled according to the calculation program stored in the ROM.
If a flag-shaped signal “on” is applied to the input terminal of the input terminal, the remote target value or the internal local target value from the first input terminal and the process variable signal applied to the second input signal are Velocity-type proportional and integral calculations are performed on the deviation, a position-type control signal given to the third input terminal is added to this calculated value, and the current position-type control signal is output to the output terminal. When the fourth input terminal is assembled with a flag-type signal "off", speed-type proportional, integral, and differential calculations are performed on the deviation, and this calculation value is applied to the previous internal A process controller characterized in that it is assembled to add position type control output values and output a current position type control signal to the output terminal.