JPH0725682U - Digital input device - Google Patents

Abstract

(57) Abstract: CONSTITUTION digital input device, which includes a self-diagnosis function, the photo-coupler a ₁ ~a _n photo for all points forced ON performing simulated input to the primary input of the coupler a " When,
Stray current prevention diodes D _{1 to} D _n for forcibly shutting off the input to each primary input section, a photocoupler a ′ for shutting off the input current, and a comparator section 4 for checking whether or not the output of each secondary output section is abnormal. And a data latch unit 3 that latches input data immediately before self-diagnosis during self-diagnosis and outputs the data to a signal processing unit, and a sequence controller 5 that controls these operations and periodically issues a self-diagnosis. There is. [Effect] The erroneous input due to the failure can be detected promptly, the signal processing section does not need to be aware of the self-diagnosis, and the software on the signal processing section is not burdened with the failure. Can be detected.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a digital input device for use in a supervisory control system or the like for inputting a digital signal to a control unit of the system, and more particularly to a digital input device having a function of self-diagnosing whether a failure has occurred. .

[0002]

[Prior art]

 Basically, a supervisory control system that remotely controls and monitors equipment of various plants such as buildings, factories, roads, electric power, water treatment, etc. is connected to multiple slave stations and each slave station via a communication path. Each slave station inputs display / measurement data from equipment and measuring equipment and sends it to the master station, and controls equipment based on commands from the master station. It is supposed to do.

The slave station has a digital input device that converts a contact input based on the ON / OFF state of the equipment into a digital signal and transmits the digital signal to a CPU (Central Processing Unit) unit.

As shown in FIG. 3, the above digital input device has a plurality of input ports d ₁ to d ₁ for connecting a plurality of non-voltage contacts b _{1 to} b _n connected in parallel on one side on the equipment side. have d _n . The aforementioned respective input ports d ₁ to d _n, is connected to a current limiting resistor R ₁ to R _n and a photo-coupler a ₁ ~a _n, closed dry contact b ₁ ~b _n in equipment side When used, current supplied from the power supply for input of DC 24V is, light emission flows through the light emitting diode a _l1 ~a _ln photocoupler a ₁ ~a _n corresponding to dry contact b ₁ ~b _n of closed and, the Fototo transistor a _t1 ~a _tn the photocoupler a ₁ ~a _n the oN state. Thus, input to the input buffer ICc ₁ to c _n of the signal voltage of the Hi · level (e.g. 5 V) is connected to the phototransistor a _t1 ~a _tn the photocoupler a ₁ ~a _n, the input buffer After being amplified by IC so as to be suitable for the processing of the CPU unit of the slave station, it is output to the CPU unit via the system bus.

[0005]

[Problems to be solved by the device]

As described above, the digital input device, typically, although photocoupler isolation is being performed, the photocoupler a ₁ ~a _n, may bad transmission by luminance reduction of the light-emitting diode a _l1 ~a _ln occurs , dry contact b ₁ ~b _n sometimes occur failure such signal input oN state even when the closed state is not transmitted to the CPU unit of the system. Moreover, the phototransistor a _t1 ~a _tn failure is held always remains in the ON state is also considered, in this case no-voltage contact b ₁ ~b _n signals of a even when the input OFF state in an open state is the system's CPU It will not be transmitted to the unit. Furthermore, there is a possibility that the voltage loss of the input power supply for driving the photo-coupler, or failure due to disconnection of the current limiting resistor R ₁ to R _n are generated.

Conventionally, even if such a failure of the digital input device occurs, no means has been taken to detect it quickly. Therefore, the operator recognizes an erroneous input after the failure occurs. It takes a long time until the master station performs erroneous control based on erroneous input. In particular, in a supervisory control system for instrumentation control of water treatment or chemical plants, there is a possibility that a very large impact may occur due to the time delay from the occurrence of a failure to the detection of the failure. Further, in the case of an input signal with little change, the operator may not notice the failure.

The present invention has been made in view of the above, and an object thereof is to provide a digital input device having a self-diagnosis function and capable of quickly detecting a failure.

[0008]

[Means for Solving the Problems]

 The digital input device of the present invention comprises a plurality of primary input sections, a plurality of secondary output sections for outputting digital signals corresponding to inputs to the respective primary input sections to a signal processing section, and the respective primary input sections. And a plurality of insulating means for electrically insulating the secondary output section from each other, and the following means are taken to solve the above problems. I am trying.

That is, the digital input device of the present invention comprises a simulated input means for performing simulated input to each of the above primary input sections, an input shutoff means for forcibly shutting off input to each of the above primary input sections, and the above Enter those states during the period when the simulated input means is performing the simulated input and during the state where the input to the primary input section is forcibly shut off by the input blocking means described above. Latch means for latching the output signal of each immediately preceding secondary output section and outputting the latched signal to the signal processing section, and control for controlling each operation of the above-mentioned simulated input means, input cutoff means, and latch means Output of each secondary output section when a simulated input is made by the means and the simulated input means described above, and when the input to each primary input section is forcibly cut off by the input cutoff means. Abnormal And a diagnostic means for diagnosing the presence or absence.

[0010]

[Action]

 According to the above configuration, the control means controls the simulated input means to perform the simulated input to each primary input section, and the input cutoff means to forcibly shut off the input to each primary input section. There is. Then, the output of each secondary output section in such a state is checked by the diagnostic means, and a failure such as a transmission failure of the insulating means can be detected. Therefore, by performing such self-diagnosis regularly, an erroneous input due to a failure can be quickly detected.

Further, during the period when the simulated input is performed by the simulated input means, and during the period when the input to each primary input unit is forcibly blocked by the input blocking means. During the self-diagnosis period (that is, during the self-diagnosis period), the latch means latches the output signal of each secondary output section immediately before entering the self-diagnosis, and outputs the latched signal to the signal processing section. It is like this. Therefore, it becomes possible to detect a failure without making the signal processing unit side aware of performing self-diagnosis and without imposing any burden on the software of the signal processing unit side.

[0012]

【Example】

 An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

The digital input device according to the present embodiment is provided in each slave station of a supervisory control system including a plurality of slave stations and a master station connected to each slave station via a communication path. is there. The slave station is designed to input display / measurement data from equipment and measuring devices and send it to the master station, and to control the equipment based on commands from the master station. Is one of various input / output modules (analog input, digital input, analog output, digital output, etc.) installed in the I / O unit of the slave station.

As shown in FIG. 1, the digital input device has a plurality of input ports d ₁ to d ₁ for connecting a plurality of non-voltage contacts b _{1 to} b _n connected in parallel on one side on the equipment side. It has a d _n, the digital signal of the Hi · level in response to the opening and closing of dry contact b ₁ ~b _n ( "1") or Lo · level ( "0"), the system bus SB It is transmitted to the CPU unit (not shown) of the slave station via

[0015] The digital input device, the input port d ₁ to d photocoupler a ₁ ~a _n as an insulating means corresponding to _n, a current limiting resistor R ₁ to R _n, input buffer ICc ₁ to c _n, In addition to the pull-up resistors R _{p1 to} R _pn and the stray current preventing diodes D _{1 to} D _n as simulated input means, a DC 24 V input power supply DPS and an input current interruption photocoupler a'as input interruption means. An all-point forced-ON photocoupler a ″ serving as a simulation input means, NOT gates 1 and 2, a data latch portion 3 serving as a latch means, a comparator portion 4 serving as a diagnostic means, and a sequence controller 5 serving as a control means. ing.

The positive terminal of the input power supply DPS is connected to the collector of a phototransistor a _t ′ constituting an input current cutoff photocoupler a ′, and the emitter of this phototransistor a _t ′ is They are connected in parallel to respective anode of the light emitting diode a _l1 ~a _ln constituting the coupler a ₁ ~a _n. The cathodes of the light emitting diodes a _{1 to} a _ln are connected to the non-voltage contacts b _{1 to} b _n via the current limiting resistors R _{1 to} R _n and the input ports d ₁ to d _n , respectively. It is supposed to be done. The non-voltage contacts b _{1 to} b _n connected in parallel are connected to the negative terminal of the input power supply DPS via the input port 6.

Therefore, when the phototransistor a _t ′ of the input current cutoff photocoupler a ′ is in the ON state, the corresponding photocoupler a _{1 to} a a in accordance with the closing / opening of the non-voltage contacts b _{1 to} b _{n. n} turns ON / OFF. On the other hand, if the ON state 'phototransistor a _t the' photocoupler a for the input current interruption, the power source for driving the photocoupler a ₁ ~a _n is blocked, closed dry contact b ₁ ~b _n / All the photo couplers a _{1 to} a _n are turned off regardless of the open state.

The light emitting diodes a _{1 to} a _ln and the current limiting resistors R _{1 to} R _n form a primary input section.

[0019] In this embodiment, the anode of迷流prevention diode D ₁ to D _n to the respective input port d ₁ to d _n are respectively connected, cathodes when de each迷流prevention diode D ₁ to D _n It is connected to the collector of the "phototransistor a _t constituting the" photocoupler a for all points forced oN. The emitter of the phototransistor a _t ″ is connected to the negative terminal of the input power source DPS.

[0020] Thus, if the ON state 'phototransistor a _t the' the input current interruption photocoupler a, by turning ON the "Photo transistors a _t the" photocoupler a for the all points forced ON, All the photocouplers a _{1 to} a _n can be turned on regardless of whether the non-voltage contacts b _{1 to} b _n are closed or opened. When the photo coupler a ″ for forced ON of all points is OFF, the stray current prevention diodes D _{1 to} D _n disconnect the input ports d _{1 to} d _n , affecting the normal operation. There is no such thing.

A power source of 5 V DC is connected to the collectors of the phototransistors a _{t1 to} a _tn forming the photo couplers a _{1 to} a _n , and a pull-up resistor R _p1 is connected to each of the emitters of the photo transistors a _{t1 to} atn. to R _pn, and the input buffer ICc ₁ to c _n for amplifying the I Uni signal suitable for processing in the CPU unit of Kokyoku are connected.

[0022] Incidentally, the secondary output portion is composed of the respective phototransistors a _t1 ~a _tn and the pull-up resistor R _p1 to R _pn each input buffer ICc ₁ to c _n.

The output of each input buffer ICc ₁ to c _n described above, it is inputted to the data latch unit 3 and the comparator unit 4. The data latch unit 3 latches the input data from the input buffer ICc ₁ to c _n in synchronization with the output sampling pulse A from the sequence controller 5, these latched data via the system Mubasu SB CPU It is designed to output to the unit.

The comparator section 4 checks whether all points ON and all points OFF are the same as expected values, and outputs the check result data B to the sequence controller 5.

The sequence controller 5 controls ON / OFF operations of the input current interruption photocoupler a ′ and the all-point forcible ON photocoupler a ″ via the NOT gates 1 and 2 and data latch. By controlling the output timing of the sampling pulse A output to the section 3, the normal mode and the self-diagnosis mode are periodically switched, and the self-diagnosis is executed periodically. The sampling pulse A output to 3 is output in synchronization with the sampling clock of a predetermined frequency.

The operation of the digital input device having the above configuration will be described below.

In the normal mode, as shown in FIG. 2, the sequence controller 5 turns on the photocoupler a ′ for shutting off the input current, turns off the photocoupler a ″ for forcibly turning on all points, and sets the predetermined value. The sampling pulse A is output to the data latch unit 3 in synchronization with the sampling clock of the frequency.

In this case, when any of the voltageless contacts b _{1 to} b _n on the equipment side is closed, the current supplied from the input power source DPS corresponds to the closed voltageless contacts b _{1 to} b _n . and emitting flows to the light emitting diode a _l1 ~a _ln photocoupler a ₁ ~a _n that, phototransistors a _t1 ~a _tn the photocoupler a ₁ ~a _n is turned oN. More thereto, is input to the input buffer ICc ₁ to c _n the data of Hi · level ( "1") is connected to the phototransistor a _t1 ~a _tn the photocoupler a ₁ ~a _n, this input After being amplified by the buffer IC, it is input to the data latch unit 3 and the comparator unit 4. On the other hand, the photo-coupler a ₁ ~a _n corresponding to dry contact b ₁ ~b _n in the closed state is the OFF state, the data latch unit 3 and the comparator unit 4 data Lo · level ( "0") Is entered.

The data input to Detara pitch portion 3 via an input buffer ICc ₁ to c _n from the photocoupler a ₁ ~a _n is latched in synchronization with the sampling pulse A, the latches data system It is output to the CPU unit via the bus SB.

Even in the normal mode, the data is checked in the comparator unit 4 and the check result data B is output to the sequence controller 5. However, the sequence controller 5 does not check the check result data input in the normal mode. The process using B is not performed.

After the operation in the normal mode is performed for a predetermined time, the sequence controller 5 switches to the self-diagnosis mode. In the self-diagnosis mode, as shown in FIG. 2, the sequence controller 5 first controls all the photocouplers a _{1 to} a _n by switching the input current interruption photocoupler a ′ from ON to OFF. To turn it off.

In this case, if there is no abnormality in the digital input device, the data of all points Lo / level (“0”) should be input to the comparator unit 4. However, if, in any of the phototransistor a _t1 ~a _tn the optocouplers a ₁ ~a _n, always failed to be kept in the ON state (hereinafter, referred to as clip failure ON state of the photocoupler) occurs If so, Hi • level (“1”) data is input from the fault photocoupler to the comparator unit 4. The comparator unit 4, the input data from the photocoupler a ₁ ~a _n is checked whether the expected values and the same of all points OFF, the outputs the check result data B to the sequence controller 5.

If the check result data B indicates that there is no abnormality, the sequence controller 5 outputs data indicating that (for example, “0”), and the data B indicates that there is abnormality. If there is, data indicating that fact (for example, "1") is output to the CPU unit.

The CPU unit transmits to the master station the data indicating whether or not there is an abnormality, which is received from the sequence controller 5, and if the data indicates that there is an abnormality, an abnormality composed of a light emitting diode or the like. An error is displayed on the display.

Subsequently, the sequence controller 5 switches the input current interruption photocoupler a ′ from OF F to ON, and also switches the photocoupler a ″ for all-point forced ON from OFF to ON, whereby all photocouplers a ′ are turned on. forced to oN state ₁ ~a _n.

In this case, if there is no abnormality in the digital input device, the data of all points Hi · level (“1”) should be input to the comparator unit 4. However, if any of the photocouplers a _{1 to} a _n causes a transmission failure (hereinafter referred to as a photo coupler OFF-state clip failure) due to a decrease in brightness of the light emitting diodes a _{1 to} a _ln . In this case, Lo level data is input from the fault photocoupler to the comparator unit 4. Further, if the voltage disappearance failure of the input power supply DPS has occurred, the inputs to the comparator unit 4 are all "0". If a failure due to the disconnection of the current limiting resistors R _{1 to} R _n or an OFF failure of the stray current prevention diodes D _{1 to} D _n has occurred, the input to the comparator section 4 corresponding to the failure section. Becomes "0". The comparator unit 4, the input data from the photocoupler a ₁ ~a _n checks whether identical or not the expected value of all points ON, the outputs the check result data B to the sequence controller 5.

Similarly to the above, the sequence controller 5 outputs the data indicating the presence or absence of abnormality in accordance with the check result data B to the CPU unit, and the CPU unit performs the same processing as described above.

As shown in FIG. 2, during the above self-diagnosis mode, the sequence controller 5 stops the output of the sampling pulse A to the data latch unit 3. Therefore, the input data output to the CPU unit via the system bus SB during the self-diagnosis mode is the data latched by the data latch unit 3 immediately before entering the self-diagnosis mode.

After the self-diagnosis operation described above is completed, the sequence controller 5 switches the photo coupler a ″ for all-point forced ON from ON to OFF, and outputs the sampling pulse A synchronized with the sampling clock to the data latch unit 3. Restart and return to normal mode.

As described above, the digital input device according to the present embodiment is provided with a plurality of primary input sections each including the light emitting diodes a _{1 to} a _ln and the current limiting resistors R _{1 to} R _n, and each primary input section. you output a digital signal corresponding to the input to the CPU unit as a signal processing unit, of consisting phototransistor a _t1 ~a _tn and the pull-up resistor R _p1 to R _pn and the input buffer ICc ₁ to c _n two A secondary output unit, and a plurality of photocouplers a ₁ to a _n each including the light emitting diodes a _{1 to} a _ln and phototransistors a _{t 1} to a _tn between the primary input unit and the secondary output units. Is electrically insulated from each other, and a simulated input means composed of a photocoupler a ″ for all-point forced ON and stray current prevention diodes D _{1 to} D _n for performing simulated input to each primary input section. , Input to each primary input section Input current interruption photocoupler a'as input interruption means for forcibly shutting off the input current, sequence controller 5 as control means for controlling the operation of the simulated input means and the input interruption means, and simulated input by the simulated input means. Comparator section as a diagnostic means for diagnosing whether or not there is an abnormality in the output of each secondary output section when the input to each primary input section is forcibly cut off by the input cutoff section. With the configuration described above, the self-diagnosis is periodically performed under the control of the sequence controller 5.

As a result, errors due to clipping failure of the photocoupler in the ON state, clipping failure of the photocoupler in the OFF state, voltage loss failure of the input power supply DPS, failure due to disconnection of the current limiting resistors R _{1 to} R _n , etc. Input can be detected quickly. In the case of the circuit configuration shown in FIG. 1, it is possible to process from the occurrence of a failure to the detection in about 100 ms. Therefore, when the above digital input device is used in the supervisory control system as in the present embodiment, there is almost no situation in which the master station performs erroneous control based on an erroneous input. For monitoring control for instrumentation control of water treatment and chemical plants, which may have a very large impact due to the time delay until detection, and for monitoring control of items where input changes occur extremely rarely. It is very effective.

Further, in the present embodiment, since the simulated input means is composed only of the photocoupler a ″ and the diodes D _{1 to} D _n , the number of additional circuit elements is small and the added diode D _{1 to} D _{n has} an OFF failure. Can be detected and is highly reliable.

In the present embodiment, the ON failure of the diodes D _{1 to} D _n (failure in which the diodes are ON in both directions) cannot be detected, and if this failure occurs, the stray flow prevention function is provided. Incorrect input occurs without working. For example, if this failure occurs in the stray current prevention diode D ₁ , the input ports d ₁ and d ₂ are always connected, and if either of the voltageless contacts b ₁ or b ₂ is closed, both points are turned on. Will occur. As a countermeasure against this, it is possible to connect a plurality of stray current prevention diodes in series between each input port. This will prevent erroneous input unless all the stray current prevention diodes connected in series have an ON failure. It never happens.

Further, the additional components for self-diagnosis are relatively low cost, the mounting area is relatively small, and the self-diagnosis function can be added without changing the constants of the existing digital input device.

Further, in the digital input device of the present embodiment, the output data of each secondary output section immediately before entering the self-diagnosis mode during the self-diagnosis mode is controlled by the sequence controller 5 in the above-mentioned configuration. The data latch unit 3 latches and outputs latch data to a signal processing unit (CPU unit).

As a result, it becomes possible to detect a failure without imposing any self-diagnosis on the signal processing unit side and without burdening the software on the signal processing unit side.

Although the photocoupler insulation is performed in the above embodiment, it may be electromagnetically insulated by a relay, for example. Further, the input current interruption photocoupler a'and the all-point forced ON photocoupler a "may also be relays.

Further, in the above embodiment, the example in which the digital input device is applied to the supervisory control system has been shown, but the present invention is not limited to this, and it can be applied to any digital input section. The above embodiments are intended to clarify the technical contents of the present invention, and should not be construed in a narrow sense by limiting to such specific examples. The spirit of the present invention and the request for utility model registration It can be implemented with various modifications within the range of.

[0049]

[Effect of device]

 As described above, the digital input device of the present invention includes: a plurality of primary input sections; a plurality of secondary output sections that output digital signals corresponding to the inputs to the respective primary input sections to the signal processing section; And a plurality of insulating means for electrically insulating between each primary input section and each secondary output section of the above, and a simulated input means for performing simulated input to each of the above primary input sections. An input shutoff means for forcibly shutting off the input to each of the above primary input sections, and during the period in which the simulated input is being performed by the simulated input means, and by the input shutoff means. Latch that latches the output signal of each secondary output unit immediately before entering those states during the period when the input to each primary input unit is forcibly cut off, and outputs the latched signal to the signal processing unit Means, the above-mentioned simulated input means, input blocking means, And the control means for controlling each operation of the latch means and the above-mentioned simulated input means, the input to each primary input section is forcibly cut off when the simulated input is performed. At this time, a diagnostic means for diagnosing whether or not the output of each secondary output unit is abnormal is provided.

Therefore, it is possible to self-diagnose the presence or absence of a failure such as a transmission failure of the insulating means, and by performing this self-diagnosis periodically, an erroneous input due to a failure can be quickly detected. Has the effect. During the self-diagnosis, the output signal of each secondary output unit immediately before starting self-diagnosis is latched and output to the signal processing unit. It is also possible to detect a failure without being conscious of the existence of the signal and without imposing any burden on the software of the signal processing unit side.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention and is an electronic circuit diagram showing a configuration of a main part of a digital input device.

FIG. 2 is an operation timing chart in the digital input device.

FIG. 3 shows a conventional example and is an electronic circuit diagram showing a configuration of a main part of a digital input device.

[Explanation of symbols]

3 Data Latch Unit (Latch Means) 4 Comparator Unit (Diagnostic Means) 5 Sequence Controller (Control Means) DPS Input Power Supply a _{1 to} a _n Photocoupler (Insulating Means) a1 _{1 to} a _ln Light Emitting Diode (Primary Input Section) R ₁ to R _n current limiting resistor (primary input) _{a t1} ~a _tn phototransistor (secondary output unit) R _p1 to R _pn pullup resistor (secondary output unit) c ₁ to c _n input buffer IC ( secondary output portion) a 'photocoupler (simulated input means for inputting current interruption photocoupler (input cutoff means) a "all points forced ON) D ₁ to D _n迷流preventing diode (simulated input means)

Claims (1)

[Scope of utility model registration request] 1. A plurality of primary input sections, a plurality of secondary output sections for outputting digital signals corresponding to inputs to the respective primary input sections to a signal processing section, each of the primary input sections and each of the secondary output sections. In a digital input device provided with a plurality of insulating means for electrically insulating the secondary output section, simulated input means for performing a simulated input to each of the primary input sections described above, and to each of the primary input sections described above. The input cutoff means forcibly cutting off the input, and the input to each primary input section is forcibly cut off during the period in which the simulated input is being performed by the simulated input means, and by the input cutoff means. Latching means for latching the output signal of each secondary output section immediately before entering those states and outputting the latched signal to the signal processing section, the simulated inputting means, the input blocking means, And each movement of the latch means Each secondary output when the simulated input is performed by the control means for controlling the above and the input to each primary input section is forcibly shut off by the above input shutoff means. A digital input device, comprising: a diagnostic means for diagnosing whether or not there is an abnormality in the output of the unit.