CN106258005B - Programmable logic controller system and arithmetic element - Google Patents

Abstract

Programmable logic controller system (100) has programmable logic controller (PLC) (10) and relay (20), which has：Simulation output unit (12), it carries out digitaltoanalogconversion；Simulation input unit (11), it carries out analog-to-digital conversion；And arithmetic element (13), the arithmetic element (13) has analog-to-digital conversion diagnostic process portion (131), if the 2nd digital value and the 1st digital value are inconsistent obtained from further analog-to-digital conversion is carried out using simulation input unit (11) after carrying out digitaltoanalogconversion to the 1st digital value using simulation output unit (12), then analog-to-digital conversion diagnostic process portion (131) are diagnosed as analog-to-digital conversion function in the presence of abnormal, the relay (20) switches over following actions, i.e., it is to be inputted from external equipment (30) by analog signal to simulation input unit (11), or the analogue value obtained from carrying out digitaltoanalogconversion to the 1st digital value from simulation output unit (12) is inputted to simulation input unit (11).

Description

Programmable logic controller system and arithmetic unit

technical field

The present invention relates to a programmable logic controller system and an arithmetic unit having a programmable logic controller, the programmable logic controller having: an analog input unit which converts an analog value into a digital value; and an analog output unit which converts Digital values are converted to analog values.

Background technique

Currently, diagnosis of an output signal of an analog output device is performed by providing a dedicated circuit inside as disclosed in Patent Document 1.

Patent Document 1: Japanese Patent Laid-Open No. 2005-173848

Contents of the invention

However, according to the above-mentioned prior art, since a dedicated circuit is required, there is a problem that unit price and development cost increase.

The present invention is proposed in view of the above circumstances, and its object is to obtain a programmable logic controller system that can perform diagnosis of analog-to-digital conversion processing or diagnosis of digital-to-analog conversion processing without using diagnostic circuits.

In order to solve the above-mentioned problems and realize the purpose, the present invention has a programmable logic controller, and the programmable logic controller has: an analog output unit that performs digital-to-analog conversion; an analog input unit that has a diagnostic function for storing the first digital value With a digital value storage unit, the analog input unit performs analog-to-digital conversion; and an arithmetic unit, the arithmetic unit has: a digital value acquisition unit for diagnosis, which acquires a first digital value from the analog input unit; a digital value setting processing unit for diagnosis , which sets the first digital value acquired from the analog input unit as the object of the digital-to-analog conversion of the analog output unit; Then, if the second digital value obtained through analog-to-digital conversion by the analog input unit is inconsistent with the first digital value, the analog-to-digital conversion diagnostic processing unit diagnoses that the analog-to-digital conversion function is abnormal. In addition, the present invention has a switching device for switching whether an analog signal is input from an external device to the analog input unit or whether the first digital value is obtained by digital-to-analog conversion from the analog output unit. Input the analog value to the analog input unit.

The effect of the invention

The programmable logic controller system according to the present invention has the effect that it is possible to perform diagnosis of analog-to-digital conversion processing or diagnosis of digital-to-analog conversion processing without using a dedicated circuit for diagnosis.

Description of drawings

FIG. 1 is a diagram showing the configuration of a programmable logic controller system according to Embodiment 1 of the present invention.

FIG. 2 is a diagram showing a configuration of an arithmetic unit of the programmable logic controller according to Embodiment 1. FIG.

FIG. 3 is a diagram showing a hardware configuration of an arithmetic unit of the programmable logic controller according to Embodiment 1. FIG.

FIG. 4 is a diagram showing the configuration of an analog input unit of the programmable logic controller according to Embodiment 1. FIG.

5 is a diagram showing a hardware configuration of an analog input unit of the programmable logic controller according to the first embodiment.

FIG. 6 is a diagram showing the configuration of an analog output unit of the programmable logic controller according to Embodiment 1. FIG.

7 is a diagram showing a hardware configuration of an analog output unit of the programmable logic controller according to the first embodiment.

FIG. 8 is a diagram showing the configuration of an output unit of the programmable logic controller according to Embodiment 1. FIG.

9 is a diagram showing a hardware configuration of an output unit of the programmable logic controller according to the first embodiment.

10 is a flowchart showing the flow of analog-to-digital conversion diagnosis processing of the programmable logic controller according to the first embodiment.

FIG. 11 is a diagram showing a modified example of the configuration of the programmable logic controller system according to the first embodiment.

FIG. 12 is a diagram showing a configuration of a programmable logic controller system according to Embodiment 2 of the present invention.

FIG. 13 is a diagram showing a configuration of a programmable logic controller system according to Embodiment 3 of the present invention.

FIG. 14 is a diagram showing a configuration of an arithmetic unit of a programmable logic controller according to Embodiment 3. FIG.

FIG. 15 is a diagram showing a configuration of an analog input unit of a programmable logic controller according to Embodiment 3. FIG.

FIG. 16 is a diagram showing a hardware configuration of an analog input unit of a programmable logic controller according to Embodiment 3. FIG.

FIG. 17 is a diagram showing a configuration of an analog output unit of a programmable logic controller according to Embodiment 3. FIG.

FIG. 18 is a diagram showing a hardware configuration of an analog output unit of a programmable logic controller according to Embodiment 3. FIG.

19 is a flowchart showing the flow of digital-to-analog conversion diagnostic processing in the programmable logic controller according to the third embodiment.

20 is a diagram showing the configuration of a programmable logic controller system according to Embodiment 4 of the present invention.

Detailed ways

Hereinafter, the programmable logic controller system and the arithmetic unit according to the embodiment of the present invention will be described in detail based on the drawings. In addition, this invention is not limited to this embodiment.

Embodiment 1

FIG. 1 is a diagram showing the configuration of a programmable logic controller system according to Embodiment 1 of the present invention. The programmable logic controller system 100 has: the programmable logic controller 10, which processes the analog signal input from the external device 30 by executing the control program; and the relay 20, which inputs the analog signal from the external device 30 to the programmable logic controller Program logic controller 10.

The programmable logic controller 10 has: an analog input unit 11, which converts an analog value input with an analog signal into a digital value through analog-to-digital conversion; an analog output unit 12, which converts a digital value input with a digital signal through digital-to-analog conversion. The value is converted into an analog value; the arithmetic unit 13, which executes the control program; the output unit 14, which outputs the control signal to the relay 20, and the control signal is related to whether the analog signal is input from the external device 30 to the analog input unit 11, or from the analog The output unit 12 inputs for switching; the power supply unit 15 supplies electric power to each unit; and the base unit 16 connects each unit to each other. The output unit 14 and the relay 20 constitute a switching device that switches whether an analog signal is input from the external device 30 to the analog input unit 11 or whether the analog signal is input from the analog output unit 12 to a first signal described later. An analog value obtained by digital-to-analog conversion of the digital value is input to the analog input unit 11 .

FIG. 2 is a diagram showing a configuration of an arithmetic unit of the programmable logic controller according to Embodiment 1. FIG. The arithmetic unit 13 has: an analog-to-digital conversion diagnostic processing unit 131 for diagnosing the analog-to-digital conversion function; Diagnosis digital value; Diagnosis digital value setting processing part 133, which sets the digital value used for analog-to-digital conversion diagnosis as the object of digital-analog conversion of the analog output unit 12; and relay control processing part 134, which makes the output Unit 14 performs switching of relay 20 . The relay control processing unit 134 constitutes a switching control unit that controls the switching device.

The relay 20 alternatively inputs the analog signal output from the external device 30 and the analog signal output from the analog output unit 12 to the analog input unit 11 . That is, by sending a command to the output unit 14 from the relay control processing unit 134, a control signal is output from the output unit 14 to the relay 20, and the operation of inputting an analog signal output from the external device 30 is switched. to the analog input unit 11 , or input the analog signal output from the analog output unit 12 to the analog input unit 11 .

FIG. 3 is a diagram showing a hardware configuration of an arithmetic unit of the programmable logic controller according to Embodiment 1. FIG. The arithmetic unit 13 has: an arithmetic unit 135 which executes a ladder program or a function module; a memory 136 which is used as a work area by the arithmetic unit 135; and a storage unit 137 which stores the program. A CPU (Central Processing Unit) can be applied as the computing device 135 . A RAM (Random Access Memory) can be used as the memory 136 . A nonvolatile semiconductor memory can be applied as the storage device 137 . The analog-to-digital conversion diagnostic processing unit 131, diagnostic digital value acquisition unit 132, diagnostic digital value setting processing unit 133, and relay control processing unit 134 shown in FIG. implemented by executing software. In addition, the above-mentioned functions may also be executed cooperatively by a plurality of computing devices and a plurality of memories.

FIG. 4 is a diagram showing the configuration of an analog input unit of the programmable logic controller according to Embodiment 1. FIG. The analog input unit 11 has: an analog-to-digital conversion unit 111 that converts an analog value into a digital value; a diagnostic digital value storage unit 112 that stores a digital value for analog-to-digital conversion diagnosis, that is, a diagnostic digital value; and a diagnostic abnormality display. A unit 113 that displays an abnormality when the diagnosis result of the analog-digital conversion function is abnormal; and a diagnostic digital value generation unit 118 that generates a diagnostic digital value based on the input range of the analog input unit 11 . The so-called input range here refers to the values that the analog signal input to the analog input unit 11 can take. In addition, a diagnostic digital value may be generated by a device different from the analog input unit 11 and stored in the diagnostic digital value storage unit 112 . The configuration of the analog input unit 11 can be simplified if a digital value for diagnosis is generated by a device different from the analog input unit 11 .

5 is a diagram showing a hardware configuration of an analog input unit of the programmable logic controller according to the first embodiment. The analog input unit 11 has: a computing device 114 that executes firmware; a memory 115 that is used as a work area by the computing device 114; a storage device 116 that stores firmware; and a display device 117 that displays information. A CPU can be applied as the arithmetic unit 114 . A RAM can be applied as the memory 115 . A nonvolatile semiconductor memory can be applied as the storage device 116 . An LED (Light Emitting Diode) lamp can be applied as the display device 117 . The analog-to-digital conversion unit 111 and the diagnostic digital value generation unit 118 shown in FIG. 4 are realized by the arithmetic unit 114 executing firmware using the memory 115 as a work area. In addition, the above-mentioned functions may also be executed cooperatively by a plurality of computing devices and a plurality of memories. In addition, the diagnostic abnormality display unit 113 shown in FIG. 4 is realized by controlling the lighting pattern of the display device 117 by the computing device 114 .

FIG. 6 is a diagram showing the configuration of an analog output unit of the programmable logic controller according to Embodiment 1. FIG. The analog output unit 12 has a digital-to-analog conversion unit 121 that converts digital values into analog values.

7 is a diagram showing a hardware configuration of an analog output unit of the programmable logic controller according to the first embodiment. The analog output unit 12 has: an arithmetic device 122 that executes firmware; a memory 123 that is used by the arithmetic device 122 as a work area; and a storage device 124 that stores firmware. A CPU can be applied as the computing device 122 . A RAM can be applied as the memory 123 . A nonvolatile semiconductor memory can be applied as the storage device 124 . The digital-to-analog conversion unit 121 shown in FIG. 6 is realized by the arithmetic unit 122 executing firmware using the memory 123 as a work area. In addition, the above-mentioned functions may also be executed cooperatively by a plurality of computing devices and a plurality of memories.

FIG. 8 is a diagram showing the configuration of an output unit of the programmable logic controller according to Embodiment 1. FIG. The output unit 14 has a control signal output unit 141 that outputs a control signal to the relay 20 .

9 is a diagram showing a hardware configuration of an output unit of the programmable logic controller according to the first embodiment. The output unit 14 has: an arithmetic device 142 that executes firmware; a memory 143 that is used by the arithmetic device 142 as a work area; and a storage device 144 that stores firmware. A CPU can be applied as the computing device 142 . A RAM can be applied as the memory 143 . A nonvolatile semiconductor memory can be applied as the storage device 144 . The control signal output unit 141 shown in FIG. 8 is realized by the arithmetic unit 142 executing firmware using the memory 143 as a work area. In addition, the above-mentioned functions may also be executed cooperatively by a plurality of computing devices and a plurality of memories.

10 is a flowchart showing the flow of analog-to-digital conversion diagnosis processing of the programmable logic controller according to the first embodiment. In step S101 , the relay control processing unit 134 sends a command to the output unit 14 so that the control signal output unit 141 outputs a control signal to the relay 20 and inputs the output of the analog output unit 12 to the analog input unit 11 .

In step S102 , the diagnostic digital value acquisition unit 132 acquires the diagnostic digital value stored in the diagnostic digital value storage unit 112 from the analog input unit 11 .

In step S103 , the diagnostic digital value setting processing unit 133 sets the diagnostic digital value to the analog output unit 12 . Since the relay 20 is controlled so that the output of the analog output unit 12 is input to the analog input unit 11 in step S101, the analog value obtained by converting the digital value for diagnosis is input from the analog output unit 12 to the analog input unit. The unit 11 is converted into a digital value by an analog-to-digital conversion unit 111 . That is, in step S103 , the second digital value is generated by performing analog-to-digital conversion by the analog input unit 11 after the first digital value, that is, the digital value for diagnosis, is converted by the analog output unit 12 .

In step S104 , the analog-to-digital conversion diagnostic processing unit 131 acquires a second digital value, which is a digital value converted by the analog-to-digital conversion unit 111 , from the analog input unit 11 .

In step S105, the analog-to-digital conversion diagnostic processing unit 131 compares the second digital value acquired from the analog input unit 11 in step S104 and the first diagnostic digital value acquired from the analog input unit 11 in step S102. Numeric values to compare. If the two are consistent, step S105 is Yes, and the analog-to-digital conversion diagnosis process ends.

On the other hand, if the digital value obtained from the analog input unit 11 in step S104 is inconsistent with the digital value for diagnosis obtained from the analog input unit 11 in step S102, then the answer is No in step S105, and in step S106, The analog-to-digital conversion diagnostic processing unit 131 notifies the analog input unit 11 of a diagnostic abnormality. When a diagnostic abnormality is notified, the diagnostic abnormality display unit 113 displays the occurrence of the diagnostic abnormality on the display device 117 . By displaying the diagnosis abnormality with a lighting pattern or lighting color unique to the diagnosis of the analog-to-digital conversion process, even if the occurrence of the diagnosis abnormality is notified by the display device 117 of the analog input unit 11, the user can recognize it. The cause may exist on the analog output unit 12 side.

In addition, in the above description, the programmable logic controller 10 having the structure in which the analog input unit 11, the analog output unit 12, and the output unit 14 are mounted on the same base unit 16 as the arithmetic unit 13 was used as an example, but The analog input unit, the analog output unit, and the output unit may be mounted on a base unit different from the arithmetic unit. FIG. 11 is a diagram showing a modified example of the configuration of the programmable logic controller system according to the first embodiment. The network unit 17 is mounted on the same base unit 16a as the computing unit 13'. Electric power is supplied to the computing unit 13' and the network unit 17 from the power supply unit 15a. The analog input unit 11', the analog output unit 12', and the output unit 14' are mounted on a base unit 16b different from the arithmetic unit 13'. The network unit 18 is mounted on the base unit 16b, and the analog input unit 11', the analog output unit 12', and the output unit 14' are mounted on the base unit 16b. Electric power is supplied to the analog input unit 11', the analog output unit 12', the output unit 14', and the network unit 18 from the power supply unit 15b. The network unit 17 and the network unit 18 are connected through a hub 19 . Therefore, the analog input unit 11', the analog output unit 12' and the output unit 14' can communicate with the computing unit 13' via the network unit 18, the hub 19 and the network unit 17.

In the analog-to-digital conversion diagnostic process in the modified example of the programmable logic controller according to Embodiment 1, the analog input unit 11 ′, the analog output unit 12 ′, and the output unit Except for the communication between 14' and the arithmetic unit 13', it is the same as that described using the flowchart of FIG. 10 .

By performing communication between the analog input unit 11', the analog output unit 12' and the output unit 14' and the operation unit 13' through the network unit 18, the hub 19, and the network unit 17, the layout of the programmable logic controller 10' The degree of freedom becomes higher.

In the programmable logic controller system according to Embodiment 1, the digital value obtained by converting the digital value used for the analog-to-digital conversion diagnosis by the digital-to-analog conversion unit 121 and then converting it by the analog-to-digital conversion unit 111 , is inconsistent with the digital value used for the diagnosis of analog-to-digital conversion, the analog-to-digital conversion diagnosis processing unit 131 diagnoses that there is an abnormality in the analog-to-digital conversion function, so it is possible to use the analog input units 11, 11' and The analog output unit 12, 12' performs diagnosis of the analog-to-digital conversion process.

Therefore, the programmable logic controller system according to the first embodiment does not require a dedicated diagnosis circuit, and by combining the analog input units 11, 11' and the analog output units 12, 12', the digital value for diagnosis is analyzed using the program ladder diagram. Compare to make a diagnosis. As a result, even the analog input units 11, 11' or the analog output units 12, 12' that do not have a dedicated diagnostic circuit can be diagnosed only by installing firmware. In addition, unit unit price and development cost can be suppressed. In addition, since the switching device is controlled by the arithmetic units 13, 13', it is not necessary to provide the analog input unit 11, 11' and the analog output unit 12, 12' with a switching device control function.

Embodiment 2

FIG. 12 is a diagram showing a configuration of a programmable logic controller system according to Embodiment 2 of the present invention. The analog input unit 11S, the arithmetic unit 13S, the output unit 14S, the power supply unit 15S, and the base unit 16S of the programmable logic controller 10S according to Embodiment 2 have functions for detecting a failure by self-diagnosis when a failure occurs, It is the same as the analog input unit 11 , arithmetic unit 13 , output unit 14 , power supply unit 15 , and base unit 16 of Embodiment 1 except that the function of forcibly turning off the safety input is adapted to the safety standard. The analog output unit 12S is the same as that of the first embodiment.

The analog input unit 11S, the arithmetic unit 13S, and the output unit 14S of the second embodiment perform duplex communication with other units and compare the communication results so as to be suitable for safety communication for fault self-diagnosis. In safety communication, when the results of duplex communication do not match, it is diagnosed that a failure has occurred.

In addition, in Embodiment 2, the program executed by the arithmetic unit 13S is a safety ladder program or a safety function module conforming to safety standards.

The processing flow of the analog-to-digital conversion diagnosis is the same as that in Embodiment 1, and thus description thereof will be omitted.

Since the programmable logic controller system according to Embodiment 2 communicates between units using safety communication, it is possible to prevent communication errors caused by communication errors in exchanging diagnostic digital values, analog conversion values, or digital conversion values between units An error occurred in the diagnosis result of digital conversion diagnosis.

Embodiment 3

FIG. 13 is a diagram showing a configuration of a programmable logic controller system according to Embodiment 3 of the present invention. The programmable logic controller system 101 has: the programmable logic controller 40, which outputs a control analog signal to the external device 60 by executing the control program; 60 output analog signal for switching. The programmable logic controller 40 has: an analog input unit 41, which converts an analog value into a digital value through analog-to-digital conversion; an analog output unit 42, which converts a digital value into an analog value through digital-to-analog conversion; an arithmetic unit 43, It executes the control program; the output unit 44 outputs the control signal to the relay 50, and the control signal switches whether the analog signal output by the analog output unit 42 is output to the external device 60 or output to the analog input unit 41; A unit 45 that supplies power to the units; and a base unit 46 that connects the units to each other. The output unit 44 and the relay 50 constitute a switching device, which switches whether the analog output unit 42 outputs an analog signal to the external device 60 or whether the analog output unit 42 performs a third digital value described later. The analog value obtained by the digital-to-analog conversion is output to the analog input unit 41 .

FIG. 14 is a diagram showing a configuration of an arithmetic unit of a programmable logic controller according to Embodiment 3. FIG. The arithmetic unit 43 has: a digital-to-analog conversion diagnostic processing unit 431 for diagnosing the digital-to-analog conversion function; a digital value for diagnosis; and a relay control processing unit 434 that causes the output unit 44 to switch the relay 50 . The relay control processing unit 434 constitutes a switching control unit that controls the switching device.

The hardware configuration of the arithmetic unit 43 of the programmable logic controller 40 according to the third embodiment is the same as that of the first embodiment. The digital-to-analog conversion diagnostic processing unit 431 , diagnostic digital value acquisition unit 432 , and relay control processing unit 434 shown in FIG. 14 are realized by executing software using a memory as a work area by an arithmetic device. In addition, the above-mentioned functions may also be executed cooperatively by a plurality of computing devices and a plurality of memories.

FIG. 15 is a diagram showing a configuration of an analog input unit of a programmable logic controller according to Embodiment 3. FIG. The analog input unit 41 has an analog-to-digital converter 411 that converts an analog value into a digital value.

FIG. 16 is a diagram showing a hardware configuration of an analog input unit of a programmable logic controller according to Embodiment 3. FIG. The analog input unit 41 has: an arithmetic device 412 that executes firmware; a memory 413 that is used as a work area by the arithmetic device 412; and a storage device 414 that stores firmware. A CPU can be applied as the computing device 412 . RAM can be applied as the memory 413 . A nonvolatile semiconductor memory can be applied as the storage device 414 . The analog-to-digital conversion unit 411 shown in FIG. 15 is realized by the arithmetic unit 412 executing firmware using the memory 413 as a work area. In addition, the above-mentioned functions may also be executed cooperatively by a plurality of computing devices and a plurality of memories.

FIG. 17 is a diagram showing a configuration of an analog output unit of a programmable logic controller according to Embodiment 3. FIG. The analog output unit 42 has: a digital-to-analog conversion unit 421, which converts a digital value into an analog value; a diagnostic digital value storage unit 422, which stores a third digital value for digital-to-analog conversion diagnosis, that is, a diagnostic digital value; An abnormality display unit 423 displays abnormality when the diagnosis result of the digital-to-analog conversion function is abnormal; and a diagnostic digital value generation unit 428 generates a diagnostic digital value based on the output range of the analog output unit 42 . The so-called output range here refers to the values that the analog signal output from the analog output unit 42 can take. In addition, a diagnostic digital value may be generated by a device different from the analog output unit 42 and stored in the diagnostic digital value storage unit 422 . The configuration of the analog output unit 42 can be simplified if a digital value for diagnosis is generated by a device different from the analog output unit 42 .

FIG. 18 is a diagram showing a hardware configuration of an analog output unit of a programmable logic controller according to Embodiment 3. FIG. The analog output unit 42 has: an arithmetic device 424 that executes firmware; a memory 425 that is used by the arithmetic device 424 as a work area; a storage device 426 that stores firmware; and a display device 427 that displays information. A CPU can be applied as the arithmetic unit 424 . RAM can be applied as the memory 425 . A nonvolatile semiconductor memory can be applied as the storage device 426 . LED lamps can be used as display means 427 . The digital-to-analog conversion unit 421 and the diagnostic digital value generation unit 428 shown in FIG. 17 are realized by the arithmetic unit 424 executing firmware using the memory 425 as a work area. In addition, the above-mentioned functions may also be executed cooperatively by a plurality of computing devices and a plurality of memories. In addition, the diagnostic abnormality display unit 423 shown in FIG. 17 is realized by controlling the lighting pattern of the display device 427 by the computing device 424 .

The configuration of the output unit 44 of the programmable logic controller 40 according to the third embodiment is the same as that of the output unit 14 in the first embodiment.

19 is a flowchart showing the flow of digital-to-analog conversion diagnostic processing in the programmable logic controller according to the third embodiment. In step S301 , the relay control processing unit 434 sends a command to the output unit 44 so that the output unit 44 outputs a control signal to the relay 50 and inputs the output of the analog output unit 42 to the analog input unit 41 .

In step S302 , the diagnostic digital value acquisition unit 432 acquires the diagnostic digital value stored in the diagnostic digital value storage unit 422 from the analog output unit 42 .

When acquisition of a diagnostic digital value is requested from diagnostic digital value acquisition unit 432 in step S302 , analog output unit 42 converts the diagnostic digital value into an analog value by digital-to-analog conversion unit 421 and outputs it to analog input unit 41 . The analog input unit 41 converts an input analog value into a digital value by an analog-to-digital conversion unit 411 . That is, in step S302 , the fourth digital value is generated by further performing analog-to-digital conversion by the analog input unit 41 after the third digital value, that is, the digital value for diagnosis, is converted by the analog output unit 42 .

In step S303 , the digital-to-analog conversion diagnostic processing unit 431 acquires the digital value converted by the analog-to-digital conversion unit 411 , that is, a fourth digital value from the analog input unit 41 .

In step S304, the digital-to-analog conversion diagnostic processing unit 431 compares the fourth digital value acquired from the analog input unit 41 in step S303 and the third diagnostic digital value acquired from the analog output unit 42 in step S302. Numeric values to compare. If the two are consistent, step S304 is Yes, and the digital-to-analog conversion diagnosis process ends.

On the other hand, if the digital value obtained from the analog input unit 41 in step S303 is inconsistent with the diagnostic digital value obtained from the analog output unit 42 in step S302, then step S304 is No, and the digital-to-analog conversion diagnostic process The unit 431 notifies the analog output unit 42 of the diagnostic abnormality in step S305. When a diagnostic abnormality is notified, the diagnostic abnormality display unit 423 displays the occurrence of the diagnostic abnormality on the display device 427 . By displaying the diagnostic abnormality with a lighting pattern or lighting color unique to the diagnosis of the digital-to-analog conversion process, even if the occurrence of the diagnostic abnormality is notified by the display device 427 of the analog output unit 42, the user can recognize it. The cause may exist on the analog input unit 41 side.

In the programmable logic controller system according to Embodiment 3, the digital value obtained by converting the digital value used for the digital-to-analog conversion diagnosis by the digital-to-analog conversion unit 421 and then converting it by the analog-to-digital conversion unit 411 , is inconsistent with the digital value used for the diagnosis of digital-to-analog conversion, the digital-to-analog conversion diagnosis processing unit 431 diagnoses that there is an abnormality in the digital-to-analog conversion function, so it can be performed using an analog input unit and an analog output unit that do not have a dedicated circuit for diagnosis. Diagnostics for digital-to-analog conversion processing. Furthermore, since the switching device is controlled by the arithmetic unit 43, it is not necessary to provide the analog input unit 41 and the analog output unit 42 with a switching device control function.

Embodiment 4

20 is a diagram showing the configuration of a programmable logic controller system according to Embodiment 4 of the present invention. The analog output unit 42S, the arithmetic unit 43S, the output unit 44S, the power supply unit 45S, and the base unit 46S of the programmable logic controller 40S according to Embodiment 4 have functions for detecting a failure by self-diagnosis when a failure occurs, The analog output unit 42 , arithmetic unit 43 , output unit 44 , power supply unit 45 , and base unit 46 of Embodiment 3 are the same except that the function of forcibly turning off the safety output is adapted to the safety standard. The analog input unit 41S is the same as the analog input unit 41 of the third embodiment.

The analog output unit 42S, arithmetic unit 43S, and output unit 44S of Embodiment 4 perform duplex communication with other units and collate the communication results, thereby being suitable for safety communication for fault self-diagnosis. In safety communication, when the results of duplex communication do not match, it is diagnosed that a failure has occurred.

In addition, in Embodiment 4, the program executed by the arithmetic unit 43S is a safety ladder program or a safety function module conforming to safety standards.

The flow of the digital-to-analog conversion diagnosis process is the same as that in Embodiment 3, and thus description thereof will be omitted.

Since the programmable logic controller system according to Embodiment 4 communicates between units using safety communication, it is possible to prevent communication errors caused by communication errors when exchanging diagnostic digital values, analog conversion values, or digital conversion values between units. An error occurred in the diagnosis result of the analog conversion diagnosis.

The configuration shown in the above embodiments represents an example of the content of the present invention, and can be combined with other known techniques, and part of the configuration can be omitted or changed without departing from the gist of the present invention.

Explanation of labels

10, 10', 10S, 40, 40S PLC, 11, 11', 11S, 41, 41S analog input unit, 12, 12', 12S, 42, 42S analog output unit, 13, 13', 13S , 43, 43S computing unit, 14, 14', 14S, 44, 44S output unit, 15, 15a, 15b, 15S, 45, 45S power supply unit, 16, 16a, 16b, 16S, 46, 46S base unit, 17 , 18 network unit, 19 hub, 20, 50 relay, 30, 60 external equipment, 100, 100', 100S, 101, 101S programmable logic controller system, 111, 411 analog-to-digital conversion part, 112, 422 digital for diagnosis Value storage unit, 113, 423 diagnostic abnormality display unit, 114, 122, 135, 142, 412, 424 computing device, 115, 123, 136, 143, 413, 425 memory, 116, 124, 137, 144, 414, 426 storage device, 117, 427 display device, 118, 428 diagnostic digital value generating unit, 121, 421 digital-to-analog conversion unit, 131 analog-to-digital conversion diagnostic processing unit, 132, 432 diagnostic digital value acquisition unit, 133 diagnostic digital value Setting processing section, 134, 434 relay control processing section, 141 control signal output section, 431 digital-to-analog conversion diagnosis processing section.

Claims (6)

1. A programmable logic controller system, characterized in that, With programmable logic controller and switching device, This programmable logic controller has: an analog output unit, which performs digital-to-analog conversion; an analog input unit having a diagnostic digital value storage unit storing a first digital value, the analog input unit performing analog-to-digital conversion; and computing unit, The arithmetic unit includes: a digital value acquisition unit for diagnosis that acquires the first digital value from the analog input unit; and a digital value setting processing unit for diagnosis that acquires the first digital value acquired from the analog input unit. 1. A digital value is set as an object of digital-to-analog conversion by the analog output unit; If the second digital value obtained by analog-to-digital conversion by the analog input unit is inconsistent with the first digital value, the analog-to-digital conversion diagnostic processing unit diagnoses that the analog-to-digital conversion function is abnormal, The switching device switches whether an analog signal is input from an external device to the analog input unit or an analog signal obtained by digital-to-analog conversion of the first digital value is obtained from the analog output unit. value is input to the analog input unit. 2. A programmable logic controller system, characterized in that, With programmable logic controller and switching device, This programmable logic controller has: an analog input unit, which performs analog-to-digital conversion; an analog output unit having a diagnostic digital value storage unit storing a third digital value, the analog output unit performing digital-to-analog conversion; and computing unit, The arithmetic unit has: a diagnostic digital value acquisition unit that acquires the third digital value from the analog output unit; After the digital-to-analog conversion, the fourth digital value obtained by further using the analog input unit to perform analog-to-digital conversion is inconsistent with the third digital value, the digital-to-analog conversion diagnostic processing unit diagnoses that the digital-to-analog conversion function is abnormal, The switching device switches whether to output an analog signal from the analog output unit to an external device or to output an analog signal obtained by digital-to-analog conversion of the third digital value from the analog output unit. The value is output to the analog input unit. 3. The programmable logic controller system according to claim 1 or 2, characterized in that, The computing unit includes a computing unit having a switching control unit that controls the switching device. 4. The programmable logic controller system according to claim 1 or 2, characterized in that, The arithmetic unit, the analog input unit, and the analog output unit perform duplex communication with other units, and when the results of the duplex communication do not match, a failure is diagnosed, and the The input to the PLC is disconnected. 5. A computing unit, which is combined with an analog input unit for analog-to-digital conversion and an analog output unit for digital-to-analog conversion to form a programmable logic controller that processes an analog signal input from an external device, The arithmetic unit is characterized in that it has: a diagnostic digital value acquisition unit that acquires a first digital value from the analog input unit; a diagnostic digital value setting processing unit that sets the first digital value to the analog output unit; and In the analog-to-digital conversion diagnostic processing unit, if the second digital value obtained by performing analog-to-digital conversion by the analog input unit after performing digital-to-analog conversion on the first digital value by the analog output unit is the same as the first If the digital values do not match, the analog-to-digital conversion diagnostic processing unit diagnoses that there is an abnormality in the analog-to-digital conversion function. 6. An arithmetic unit, which is combined with an analog input unit for analog-to-digital conversion and an analog output unit for digital-to-analog conversion to form a programmable logic controller that outputs an analog signal for control to an external device, The arithmetic unit is characterized in that it has: a diagnostic digital value acquisition unit that acquires a third digital value from the analog output unit; and In the digital-to-analog conversion diagnosis processing unit, if the fourth digital value obtained by performing analog-to-digital conversion by the analog input unit after performing digital-to-analog conversion on the third digital value by the analog output unit is the same as the third digital value If the digital values do not match, the digital-to-analog conversion diagnostic processing unit diagnoses that there is an abnormality in the digital-to-analog conversion function.