JPH0373002B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a digital control device,
In particular, it relates to distributed digital control devices.

[Technical background of the invention and its problems]

Distributed digital control devices have evolved from multi-loop systems in which one microprocessor controls multiple loops to one-loop systems in which one microprocessor controls one loop.

FIG. 1 is a conceptual diagram of a distributed digital process control device.

An operator's console 11 with a CRT is installed in the central operation room, and the operator monitors the process and performs operations while viewing the CRT. Additionally, for important loops, a manual backup station 12 is installed that has the same man-machine interface as a conventional analog controller. Controller 1 that performs control calculations
3 is housed in a chassis inside a freestanding casing.

This type of system is intended for CRT operation, which is performed while viewing the CRT.
The manual backup station 12 is an instrument that should be installed as little as possible. However, since it is desired to monitor critical or important loops in the same way as a conventional analog controller, it is common to install a backup station 12 for such loops.

FIG. 2 shows an example of the configuration when a backup station is connected. The controller 13 receives process quantity signals from sensors 21 such as flow meters, thermocouples, and pressure gauges that measure process quantities such as flow rate, temperature, and pressure via a signal line 22, and receives process quantity signals PV and set values SV. (The set value signal representing the set value is output from the signal line 23) The operation amount MV (the analog voltage signal representing this is output from the signal line 24) is generated such that the deviation from the set value signal is zero. be. In order to achieve such functions, the controller 13 is provided with a microcomputer including an arithmetic control section 25, a data bus 26, and the like. Reference numeral 27 is an input/output port for changing the control mode of the controller 13 from the backup station 12. 28 is a register that receives a signal KPV corresponding to the process amount signal PV.
is memorized. This KPV is KPV = PV if the characteristic of the sensor 21 is linear, and if it has a square characteristic like a flowmeter using an aperture, KPV
=√, and if it is non-linear like a temperature sensor, KPV=(t)PV. Here, (t) is a coefficient dependent on temperature t. That is, KPV is a linearized signal and is calculated by the calculation control section 25. Next, 29 is a digital-to-analog converter.

Reference numeral 30 denotes an up-down counter with a preset for storing a set value SV, and the contents of the counter, that is, the set value SV can also be changed by the SV-UP/DOWN signal from the backup station 12. 31 is a digital-to-analog converter, and the analog-converted setting value is sent to the signal line 23.
Output to. 32 is an up-down counter with a preset for storing the manipulated variable MV;
It can also be changed by a signal. 33 is an analog-to-digital converter that outputs to the signal line 24. The block 34 consisting of the counter 32 and the converter 33 is backed up by an emergency power source such as a battery so that it can operate even when the power source of the controller 13 is abnormal. 35 is an analog-to-digital converter;
The analog signal from sensor 21 is converted into digital format and transmitted to data bus 26.

The backup station 12 includes a front panel 41, which is shown schematically. Reference numeral 42 denotes a display, which includes a process quantity pointer 43 which swings in accordance with the output of the converter 29 of the controller 13 to display the process quantity KPV, and a process quantity pointer 43 which swings in accordance with the output of the converter 31 of the controller 13 to display the set value SV. It has a setting guideline 44 to display. In addition, the operation amount display 4
5, and its pointer 46 indicates the amount of operation. This manipulated variable display 45 is of an ammeter type, and the analog voltage of the signal line 24 is converted to a voltage-current converter 47.
It responds to the amount of electricity converted into a current signal. This electric quantity, that is, the operating output in the form of a current signal is transmitted to an operating end 48 such as a valve drive device for regulating a process quantity.
sent to.

51, 52, and 53 are push buttons for changing the control mode of the controller 13; button 51 is for cascade mode in auto mode, button 52 is for other auto modes, and button 53 is for manual mode. When the push button is operated, a signal is given to the input/output port 27, and when the controller 13 accepts the signal, the button lights up to indicate that fact. 54 and 55 are push buttons for changing the set value SV, and 54 is the set value
55 is for increasing the SV, and 55 is for decreasing the set value SV.
These selection operations produce SV-UP/DOWN signals. 56 and 57 are push buttons for changing the manipulated variable MV, and when operated, the MV-
Generates UP/DOWN signals.

In such a configuration, the backup station 12 can be used for monitoring and operation in the same way as a conventional analog controller. Furthermore, even if, for example, the arithmetic control section 25 of the controller malfunctions, the operation end 48 can be manually operated using the push buttons 56, 57 and the operation amount display 45, that is, can be backed up. Even if the power supply to the controller 13 fails, the block 34 can be backed up in the same way since it is backed up by the emergency power supply as described above.

However, when the arithmetic control unit 25 of the controller 13 fails, the display 42, which operates based on the signal from the controller 13, also stops operating, and the operator is therefore unable to recognize the process amount KPV. I become confused. In other words, in the case of FIG. 2, there was insufficient consideration for backup with respect to the instruction of the process amount KPV.

Furthermore, although this configuration example is for the case where the backup station 12 is connected, if the backup station is not connected, that is, only the controller 13 is connected, the voltage-current converter 4
The output of the digital-to-analog converter 33 is sent to the operating end through an output card equipped with only 7. Therefore, the entire system is divided into important loops with a manual backup station and loops without it (loops that only require the controller 13).
Classify and instrument. For loops that were classified at the time of system design as requiring only the controller 13, it was not planned to arbitrarily connect backup stations as needed.
However, recently it has become desirable to freely connect a backup station to any loop at any time.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a digital control device that allows an operator to manually adjust the operation amount while visually observing the process amount when performing a backup operation at the backup station when a controller with a backup station fails. It is in.

Another object of the present invention is to provide a digital control device that allows the backup station to be freely connected to any controller.

[Summary of the invention]

The present invention provides a controller that generates a manipulated output representing a manipulated variable for controlling a process amount, and that can automatically generate a manipulated output that makes the process amount a predetermined value, and a controller that can be connected to and separated from the controller. a backup means that is freely provided and that, when connected to the controller, enables manual setting of the operation output; and an abnormality detection means that detects an abnormality of the controller;
The controller has first means for generating a first signal responsive to a process quantity signal representing the process quantity; the backup means has second means for generating a second signal responsive to the process quantity signal;
A process of displaying according to the first signal when the abnormality detecting means does not detect an abnormality, and displaying according to the second signal when the abnormality detecting means detects an abnormality. The present invention resides in a digital control device having an amount display means and an operation amount display means for displaying a display according to the operation output.

[Embodiments of the invention]

FIG. 3 is a conceptual diagram of a distributed process control system to which manual backup stations can optionally be connected, in accordance with one embodiment of the present invention. The controller 13 and backup station 12 are connected via a terminal board 61. That is, the controller 13 is connected to the board 61 with a cable 62 and a connecting connector 63, the backup station 12 is connected to the board 61 with a cable 65 and a connecting connector 64, and the sensor 21 and the operating end 48 are connected to a terminal block 66. are connected to each other. Here, the terminal block 66 may be provided separately from the terminal board 61 having the connectors 63 and 64. In this embodiment, the controller 13 that you want to back up manually
If the connector 64 is connected, backup can be performed manually at any time. The details will be explained below with reference to FIG.

In FIG. 4, parts that are equivalent to or similar to those shown in FIGS. 2 and 3 are designated by the same reference numerals as in FIGS. 2 and 3, and their explanations will be omitted. First, the converter 47a that performs voltage-current conversion of the manipulated output is connected to the block 34 of the controller 13.
a, and the operation output as a current signal is generated on the signal line 24a. Here, block 34a is backed up by a battery. A normally closed contact 71 is incorporated in the backup station connection connector of the terminal board 61. This contact 71 is closed when the backup station 12 is not connected, and opened when the backup station 12 is connected. For example, as shown in FIG. Use. Note that 73 indicates a connection piece for a signal line. In FIG. 4, when the backup station 12 is not connected, the operation output signal line 24a is directly connected to the operation end 48 through the closed contact 71, and when the backup station 12 is connected, the operation output signal line 24a is directly connected to the operation end 48. Contact point 71
Since the signal line 24a is open, the signal line 24a is connected to the operation end 48 via the operation amount display 45 in series. In this way, the connection of the operation output is changed as the backup station is connected to and removed from the backup station.

In FIG. 4, signal line 2 from sensor 21
2 is connected to the backup station 1 via the terminal board 61 as shown by the signal line 22a.
2 is also connected. Back up station 1
2 is provided with a changeover switch 75 whose common terminal is connected to the display 42, and the controller 13
When the controller is normal, the process quantity pointer 43 of the display 42 swings according to the signal from the converter 29 of the controller 13 (representing the first signal KPV according to the process quantity PV), and when the controller is abnormal, the signal line 2
It is made to swing according to the second signal corresponding to the signal PV of 2a. In order to operate the switch 75 in this way, the controller 13 is provided with an abnormality monitoring device 76 that detects an abnormality in the arithmetic control unit 25 and an abnormality monitoring device 77 that detects an abnormality in the analog-digital converter 35. Monitoring device 7
The abnormality detection signals 6 and 77 are outputted from the controller 13 via the NOR circuit 78 and then transmitted via the terminal board 61 to the switch 75 of the backup station.

Further, when an abnormality occurs in the controller 13, it is preferable to turn on the abnormality indicator light 79 provided on the front panel 41 of the backup station. The conditions for detecting an abnormality in the controller are (1) loss of power to the controller, (2) abnormality in the arithmetic control unit 25 (runaway program, etc.), (3) analog-to-digital converter 3
There are 5 abnormalities, etc.

According to this embodiment, when an abnormality occurs in the controller 13, the switch 75 switches from the illustrated connection state to the connection to the contact point 75a in response to a signal from the NOR circuit 78, and the process amount is indicated by the pointer 43. The operator can know the process quantity,
You can manually set the manipulated variable more reliably.

Here, in the above-mentioned system, the deflection D of the pointer 43 when the controller 13 is abnormal is determined by the sensor 21.
This shows the direct process quantity PV from .
However, as mentioned above, if the sensor 21 is a flow meter, etc., it is desirable to use KPV=√; when the controller 13 is normal, the controller
KPV is output. That is, the controller outputs the first signal KPV according to the process amount PV. Therefore, the dotted line block 81 is shown in Fig. 4.
It is desirable to provide the circuit shown in FIG. 6 in the portion shown by . The block 81 supplies a second signal corresponding to the PV to the contact 75a, and by inserting a pin, the switch 82 selects either conduction, so that the PV is caused to swing directly to the pointer 43 or to the route calculation circuit 83.
It is configured to either cause the pointer 43 to swing √ through the cursor. According to this,
If the sensor 21 is a flow meter with square-law characteristics, the process amount display on the display 42 in the event of an abnormality in the controller 13 is controlled based on the selection information set in advance by setting the pin selection to the route calculation side. The runout D becomes √, which is even more convenient.

By the way, in FIG. 4, the operation amount display 45
has been described as an ammeter type, but in the case of a voltmeter type, the output of the digital-to-analog converter 33 is made to swing the display 45 as shown by the signal line 24b indicated by a dotted line, and the operating end 48 is The voltage-to-current converter 4 is connected to the signal line 24c indicated by a dotted line.
It is sufficient to supply the output of 7a. In this case, the voltage −
Care must be taken because the indicator 45 will not display the amount of electricity applied to the operating end 48 when the current converter 47a fails.

Further, the digital-to-analog converter may be of a pulse width modulation type, that is, of a type in which the width of its output pulse changes in an analog manner depending on the input digital signal. In particular, when this type is used as the converters 29 and 31, there is an advantage that errors in signal transmission are reduced even if the distance between the controller 13 and the backup station is long.

FIG. 7 shows another embodiment of the invention. In this embodiment, the backup station 12 is also provided with an arithmetic control section 85. This arithmetic control section 85 may be considerably smaller than the arithmetic control section 25 of the controller 13. 86 is a data bus, controller 1
a communication control unit 87 for data communication with 3;
Analog port 88 for giving process quantities and set values SV, push buttons 54, 55, 51, 52,
53 and an analog-to-digital converter 90 for the signal from the sensor 21, respectively. The controller 13 includes a communication control section 36 connected to the data bus 26.
The communication control unit 36 and the communication control unit 87 of the backup station 12 exchange data between the controller 13 and the backup station 12. Such data communication has the effect of reducing the number of communication lines between controller 13 and the backup station.

The backup station 12 is provided with an abnormality monitoring device 91 for detecting abnormalities in its arithmetic and control unit 85 and for detecting abnormalities in the controller through data from the controller 13. An abnormality in the controller 13 can be detected by determining whether or not regular communication from the controller 13 has stopped. On the other hand, the controller 13 is provided with an abnormality monitoring device 77a that detects an abnormality in the digital-to-analog converter 35 and outputs the result to the data bus 26.

Next, to explain the backup method of process amount display in FIG.
During regular communications, data currently being sent to the backup station 12 is always sent with a flag indicating whether or not a route has been calculated.

As shown in the flowchart of FIG. 8, when the controller 13 is normal (for example, when communication is normal and the analog-to-digital converter 35 of the controller 13 is normal), the The process amount KPV is directly displayed as the deflection D of the pointer 43 (see 101 and 102 in FIG. 8).

If the controller is abnormal (if there is an abnormality in the above communication or if there is an abnormality in the converter 35),
The backup station 12 starts backup based on information from the controller 13, ie, the presence or absence of a flag. That is, when the route calculation flag is present, the station 12 calculates the route of the PV value directly taken in and displays it as deflection D=√ (see 103 and 104 in FIG. 8).
When there is no route calculation flag, the calculation described below is performed and the LPV is displayed as deflection D (see 103 and 105 in FIG. 8). Here, the coefficient L is
A normal situation just before an error occurs in the controller.
The KPV value is sent to station 12 immediately after the abnormality occurs.
This is the value obtained by dividing by the PV value directly taken in.
In other words, coefficient: L = KPV just before the abnormality occurs / P immediately after the abnormality occurs
V deflection: D=L×PV.

The reason for using such a constant L is as follows. For example, the temperature process variable is not linear, although it is not a root characteristic, so it is often linearized in the controller as KPV=(t)PV, as described above. Here, (t) is a linearization coefficient that depends on temperature t. Therefore, it is better to calculate a coefficient L that approximates the linearization coefficient and display the LPV than to display the PV value as it is. The linearization coefficient varies depending on the input process signal, so if you perform an operation that changes the process amount significantly, it will deviate from the correct instruction, but in reality, it is necessary to prevent the PV value from changing significantly. This is because it is normal to operate
Even if LPV is used, the backup function will be strengthened in practical terms.

In what I just explained, do you do root calculations?
A flag was used to identify whether LPV calculation was to be performed, but in order to make this distinction, pin selection in the backup station 12 required, for example, a potential of +5V for root calculation, and a potential of +5V for LPV calculation. It is also possible to provide a mechanism for applying a zero potential to each, and to read this for identification.

By the way, if an abnormality has already occurred in the controller at the time the backup station 12 is connected, the above LPV calculation is impossible. Therefore, an example in which the PV value is displayed instead of the LPV in such a case will be described next.

For this purpose, a flag, ie, an initialize flag, is provided in the backup station 12, which is reset when normal data is received from the controller 13 at the backup station 12. Therefore, even if the backup station 12 is connected, if the initialization flag is set, it already indicates that the controller is abnormal.

As shown in FIG. 9, if there is no initialization flag, that is, if the controller 13 is normal when connected to the station 12, the runout D will not occur if no abnormality occurs in the controller.
KPV (see 112, 113 in Fig. 9), and then an abnormality occurs in the controller 13, and when calculating the route, the deflection D becomes √ (see 112, 113 in Fig. 9).
114, 115), then the controller 13
When an abnormality occurs in LPV calculation, the deflection D becomes LPV (see 112, 114, and 116 in FIG. 9).

Next, when there is an initialization flag, the deflection D becomes √ when calculating the root (see 111, 117, 115 in Figure 9), and in the same case
When calculating LPV, display the PV value as it is as deflection D (111, 117 in Figure 9,
118). In addition, in the flow shown in FIG. 9, it is preferable to identify whether it is a root calculation or an LPV calculation by storing it in memory in the backup station 12 by selecting a pin or the like.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to back up process amount display, and
A digital control device can be obtained that allows the backup station to be freely connected to any controller.

[Brief explanation of drawings]

Fig. 1 is a conceptual diagram of a distributed digital control device, Fig. 2 is an explanatory diagram of a conventional controller with a backup station, Fig. 3 is a conceptual diagram of a digital control device based on the present invention, and Fig. 4 is a conceptual diagram of a digital control device according to the present invention. Block diagram illustrating an embodiment based on the fifth
The figure is a perspective view for explaining the contact 71 in FIG.
6 is a circuit diagram representing block 81 of FIG. 4, FIG. 7 is a circuit diagram showing another embodiment of the present invention, and FIGS. 8 and 9 are diagrams for explaining the embodiment of FIG. 7, respectively. It is an explanatory diagram. 12...backup station, 13...
Controller, 61...Terminal board, 71
. . . Normally closed contact that opens when the backup station is connected, 75 .

Claims (1)

[Scope of Claims] 1. A controller that generates a manipulated output representing a manipulated variable for controlling a process amount, and that can automatically generate a manipulated output that makes the process amount a predetermined value; a backup means which is provided so as to be able to come into contact with and separate from the controller, and which, when connected to the controller, enables manual setting of the operation output; and an abnormality detection means which detects an abnormality of the controller; The controller has first means for producing a first signal responsive to a process quantity signal representing the process quantity, and the backup means has second means for producing a second signal responsive to the process quantity signal; When the abnormality detection means does not detect an abnormality, a display is performed according to the first signal, and when the abnormality detection means detects an abnormality, the display is performed according to the second signal. a display means, and
A digital control device comprising a manipulated variable display means for displaying a display according to the manipulated output. 2. In the device according to claim 1,
After the manipulated output on the digital display is converted from digital to analog in the controller, it is sent to the manipulated variable display means of the backup means, and further voltage-to-current converted in the controller, followed by an operating end for adjusting the process amount. Digital control device sent to. 3. In the device according to claim 1,
The operating output generated by the controller is a current signal, and such operating output is sent directly to the operating terminal for adjusting the process amount when the backup means is not connected, and when the backup means is connected. 2 is a digital control device including a switching means for sending a signal to the operating end via an operation amount displaying means of the backup means. 4. In the device according to claim 3,
The switching means is a digital control device that is provided on the connector of the backup means and includes a normally closed contact that opens when the connector is connected. 5. In the device according to claim 1,
The second means is based on preset selection information,
A digital control device that uses a process amount signal as it is or calculates a route of the process amount signal and uses it as a second signal. 6. In the device according to claim 1,
The second means is based on information from the controller,
The second signal is obtained by calculating the route of the process quantity signal, or by multiplying the process quantity signal by the first signal immediately before the occurrence of an abnormality in the controller and dividing by the process quantity signal immediately after the occurrence of an abnormality in the controller. A digital control device. 7. In the device according to claim 1,
The second means is based on preset selection information,
The value obtained by calculating the route of the process quantity signal or by multiplying the process quantity signal by the first signal immediately before the occurrence of an abnormality in the controller and dividing the process quantity signal immediately after the occurrence of an abnormality in the controller is used as the second signal. A digital control device. 8. In the device according to claim 1,
If the controller is already abnormal at the time when the backup means is connected to the controller, the second means uses the process amount signal as it is or calculates the route of the process amount signal and converts it to the second signal based on the selection information set in advance. If the controller is normal at the time when the backup means is connected to the controller, the process amount display means is in the first state.
When an abnormality occurs in the controller, the second means calculates the route of the process quantity signal based on preset selection information, or displays the process quantity signal according to the controller. A digital control device, wherein the second signal is a value obtained by multiplying the first signal immediately before the occurrence of an abnormality by the process amount signal immediately after the occurrence of the abnormality in the controller.