JP4103145B2 - Input module - Google Patents

Description

According to the present invention, an external power source and contacts of all channel input switches via field wiring are externally connected, and one of the external power sources is connected to one of the contact points of all channel input switches. Is connected to the common potential via the first current detection resistor of all channels, and the other of the contact points of the input switches of all channels is connected to the common potential. The present invention relates to wiring diagnosis of an input module including voltage reading means for monitoring a voltage between terminals .

  Prior art documents related to the input module include the following.

Japanese Patent Laid-Open No. 10-074104

  In a safety control system that inputs a trip request from a plant and stops the plant, contact information of an input switch that is activated by the trip is guided to a terminal of an input module of the safety control system via a field wiring.

  If it is input that the input switch has apparently changed due to an abnormality in the field wiring or an abnormality in the input module, the safety control system will perform an erroneous stop operation, which will seriously affect the plant operation. There is a risk of giving.

  Therefore, the safety control system is required to have a diagnostic function that can reliably detect abnormalities in the field wiring and abnormalities in the input module, and can eliminate the input of contact information of the input switch when these abnormalities occur. .

  FIG. 5 is a functional block diagram showing a general configuration example of a conventional input module. Reference numeral 10 denotes a multipoint input module, which includes a control device 11 and terminals 1 to 4. A common external power supply 20 (voltage: V_FIN) is connected between the terminals 1 and 4. Note that elements indicated by bold lines are multi-point common elements, and elements indicated by thin lines are elements having x points for each channel.

  The terminals 2 and 3 are connected to the contacts of the input switch S0 via field wires L1 and L2, respectively. A plurality of sets of field wirings L1, L2, input switch S0, and terminals 2 and 3 exist for each channel, but only one channel is omitted for simplicity.

  Inside the multipoint input module 10, the terminal 1 is directly connected to the terminal 2, and one of the external power sources 20 is connected to one of the contacts of the input switch S0. The terminal 3 is connected to the common potential via the current detection resistor R1, and the terminal 4 is directly connected to the common potential V_COM.

  With this configuration, when the input switch S0 is turned on, the current I flows through the resistor R1, and the terminal voltage Ei becomes the external power supply voltage V_FIN. Since the current I does not flow when the input switch S0 is off, the voltage across the resistor R1 becomes the common potential V_COM. The control device 11 receives the inter-terminal voltage Ei as an input signal, and determines the on / off state of the input switch S0 based on the binary values of the voltages V_FIN and V_COM.

  FIG. 6 is a table in which wiring abnormalities that may occur when the circuit configuration described in FIG. 5 is adopted are classified. The location of the occurrence of abnormality is classified into external wiring abnormality (A) and in-module abnormality (B).

  The external wiring abnormality (A) has three types of abnormality modes: external short circuit (1), external disconnection (2), and external channel short circuit (3). An external short circuit is a case where terminals 3 and 2 are short-circuited or terminals 3 and 1 are short-circuited. The external disconnection is a case where the terminal 2 or the terminal 3 is disconnected, but includes a case where the terminal 3 and the terminal 4 are short-circuited. The external channel short circuit is a case where the terminal 3 is short-circuited with the terminal 3 of another channel.

  The in-module abnormality (B) has three types of abnormality modes: internal ON fixing (4), internal OFF fixing (5), and internal channel short circuit (6). Internal ON sticking is when the input circuit in the module sticks in the ON direction. Internal OFF sticking is when the input circuit in the module sticks in the OFF direction. The internal channel short circuit is when the input circuit in the module is short-circuited with the input circuit of another channel.

  In the conventional input module shown in FIG. 5, the diagnostic function for detecting the external wiring abnormality (external short circuit, external disconnection, short circuit between external channels) and internal abnormality (ON sticking, OFF sticking, short circuit between channels) described in FIG. Therefore, there is a problem that the input of the target channel becomes unstable when a wiring abnormality or an internal abnormality occurs.

  Therefore, when the conventional input module shown in FIG. 5 is adopted as the input module of the safety control system, it is assumed that the state of the input switch S0 is apparently changed due to an abnormality in the field wiring or an abnormality in the input module. The safety control system will perform an erroneous stop operation, which will seriously affect the plant operation.

  Therefore, the problem to be solved by the present invention is to realize an input module having a diagnosis function that can detect and detect a field wiring abnormality, a state change caused by an abnormality in the module, and a state change caused by ON / OFF of an input switch. There is to do.

In order to achieve such an object, the configuration of the present invention is as follows.
(1) The external power supply and the contacts of the input switches of all the channels via the field wiring are connected externally, and one of the external power supplies is connected to one of the contacts of the input switches of all the channels internally. The other is connected to a common potential, and the other contact of the input switches of all channels is connected to the common potential via the first current detection resistors of all channels, and the terminals of the first current detection resistors of all the channels In an input module comprising voltage reading means for monitoring the voltage between
First switch means connected between the contact points of the input switches of all the channels and normally operated off;
A second switch means that is normally turned on, and simultaneously connects the other of the contact points of the input switches of all the channels to the second current detection resistors of all the channels that give input signals to the voltage reading means;
Diagnostic management means for outputting a first operation signal for operating on / off of the first switch means and a second operation signal for operating on / off of the second switch means;
With
The diagnosis management means sequentially turns on the first switch means for each diagnosis target channel with the second switch means turned on at the same time, and is generated in the second current detection resistor during the operation period. The input signal level of the channel other than the diagnosis target channel is monitored via the voltage reading means, and the channel whose input signal level indicates the voltage level of the external power supply is short-circuited to the diagnosis target channel outside the input module. An input module characterized by diagnosing a short circuit abnormality between external channels .

(2) The diagnosis management means sequentially turns on the first switch means for each diagnosis target channel with the second switch means turned off at the same time, and detects the second current during the operation period. The input signal level of the channel other than the diagnosis target channel generated in the resistor is monitored via the voltage reading means, and the channel whose input signal level indicates a voltage level other than the common potential is turned on in the input module. The input module according to (1), wherein the input module is diagnosed as having an internal ON fixing abnormality .

(3) The diagnosis management means sequentially turns on the first switch means for each diagnosis target channel with the second switch means turned on at the same time, and the second current detection resistor is operated during the operation period. The input signal level other than the diagnosis target channel occurring in the monitor is monitored via the voltage reading means, and the channel whose input signal level does not become the voltage level of the external power supply is fixed to the off side inside the input module. The input module according to (1), which is diagnosed as an internal OFF sticking abnormality .

(4) Third switch means which is operated by a third operation signal output from the diagnosis management means and connects one of the external power supplies to the second current detection resistors of all the channels, which is normally operated off. Provided,
The diagnosis management means sequentially turns on the third switch means for each diagnosis target channel with the second switch means turned on at the same time, and generates the second current detection resistor during the operation period. The input signal level other than the diagnosis target channel is monitored via the voltage reading means, and a channel whose input signal level indicates the voltage level of the external power supply is synchronized with the ON operation of the diagnosis target channel inside the input module. The input module according to (1), wherein an internal channel short-circuit abnormality that is short-circuited with the diagnosis target channel is diagnosed .

As is apparent from the above description, the present invention has the following effects.
(1) External short circuit and external disconnection abnormality can be detected by input level diagnosis.
(2) A short circuit abnormality between external channels can be detected by pulse diagnosis.
(3) The ON / OFF diagnosis can detect internal wiring ON sticking abnormality, OFF sticking abnormality and inter-channel short circuit abnormality.
(4) Based on the above, it becomes possible to identify and detect a state change due to an abnormality in the field wiring, a module internal abnormality, and a state change due to ON / OFF of the input switch, and the state change due to the abnormality is mistaken as a state change of the input switch. A safe input module can be realized.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a functional block diagram showing an embodiment of an input module to which the present invention is applied. The same elements as those of the conventional input module described with reference to FIG. Hereinafter, the characteristic part of the present invention will be described.

  In FIG. 1, reference numeral 100 denotes a multipoint input module to which the present invention is applied, and the control apparatus 101 includes a voltage reading unit 101a and a diagnosis management unit 101b for inputting the read voltage.

  In the vicinity of the input switch SW0, Q1 is a first diagnostic element realized by a resistor, and is connected in series between one of the contacts of the input switch SW0 and one of the field wirings L1, L2. Q2 is a second diagnostic element that is also realized by a resistor, and is connected in parallel between the contacts of the input switch SW0. These diagnostic elements Q1 and Q2 form a diagnosis unit A for executing input level diagnosis.

In the multipoint input module 100, the common point P1 is connected to the terminal 1 and the terminal 2, and the common point P2 is connected to the terminal 3 and the first current detection resistor R1. The first switch means SW1 for pulse diagnosis is provided for each channel, and is connected between the common point P1 and the terminal 3, and is on / off controlled by the first operation signal M1 from the diagnosis management means 101b, and is normally turned off. It is being operated. The first switch means SW1 forms a diagnosis unit B that performs pulse diagnosis.

The second switch means SW2 that is common to multiple points is a switch that separates the external input and the inside of the module. The second switch means SW2 is connected between the common point P2 and the common point P3, and is simultaneously turned on / off by the second operation signal M2 from the diagnosis management means 101b. Is normally operated on.

  Between the common point P3 and the common potential, a voltage dividing circuit of resistors R2 and R3 forming a second current detection resistor is connected, and the divided voltage is inputted to the current reading means 101a as an input signal Ei.

  The third switch means SW3 is an ON / OFF diagnosis switch connected between the common point P1 and the common point P3. The third switch means SW3 is provided for each channel, and is on / off controlled by a third operation signal M3 from the diagnosis management means 101b. It is normally operated off. The second switch means SW2 and the third switch means SW3 form a diagnosis unit C that performs ON / OFF diagnosis.

According to such a circuit configuration, the voltage of the terminal 3 has the following four levels, and the voltage reading unit 101a of the control device 101 can identify and read out each of the four levels.
V_FIN: Voltage level of external power supply 20
V_H: Voltage level when input switch SW0 is on
V_L: Voltage level when input switch SW0 is off
V_COM: Common potential level.
Here, the value of each voltage level is V_FIN>V_H>V_L> V_COM.

  During normal operation, SW1 is turned off, SW2 is turned on, and SW3 is turned off by operation signals M1 to M3 of the diagnosis management unit 101b of the control device 101. When the input switch SW0 is OFF, the voltage at the terminal 3 becomes V_L, and the control device 101 determines that OFF is input via the input signal Ei. When the input switch SW0 is on, the voltage at the terminal 3 is V_H, and the control device 101 determines that on is input via the input signal Ei.

  Next, various abnormality diagnosis methods using the diagnosis units A, B, and C will be described in the order of the abnormality modes (1) to (6) classified in FIG.

External short circuit (1) and external disconnection (2):
In order to detect disconnection or short circuit of the external wiring, the diagnosis unit A performs input level diagnosis. The external short circuit means a case where the terminal 2 and the terminal 3 are short-circuited or the terminal 3 and the terminal 1 are short-circuited. The external disconnection means a case where the terminal 2 or the terminal 3 is disconnected or the terminal 3 and the terminal 4 are short-circuited. The input level diagnosis procedure is described below.

  First, the external short circuit will be described. In order to detect an external short circuit, the 1st diagnostic element Q1 of the diagnostic part A is required. When the input switch SW0 is on, the terminal 3 is divided by the first diagnostic element Q1 and becomes a voltage lower than V_FIN. This is the V_H level. When the V_H level is measured, the control apparatus 101 determines that the input switch SW0 is turned on. When the input switch SW0 is off, the terminal 3 is at the V_COM level, and the control device 101 determines that the input switch SW0 is off.

  On the other hand, if the terminal 2 and the terminal 3 are short-circuited, or the terminal 3 and the terminal 1 are short-circuited, the terminal 3 becomes the V_FIN level of the power supply voltage, thereby detecting an external short circuit.

  Next, external disconnection will be described. In order to detect an external disconnection, the second diagnostic element Q2 of the diagnostic unit A is necessary. When the input switch SW0 is on, the terminal 3 is at the V_FIN level, and the control device 101 determines that the input switch SW0 is on. When the input switch SW0 is off, the terminal 3 has a voltage higher than V_COM due to the influence of the second diagnostic element Q2. This is the V_L level. When the V_L level is measured, the control device 101 determines that the input switch SW0 is turned off.

  On the other hand, if the terminal 2 is disconnected, the terminal 3 is disconnected, or the terminal 3 and the terminal 4 are short-circuited, the terminal 3 is at the V_COM level, whereby an external disconnection abnormality can be detected.

  Although external short circuit and external disconnection can be detected independently, both the first diagnostic element Q1 and the second diagnostic element Q2 can be mounted as shown to detect both short circuit and disconnection. Is. In this case, the short circuit can be read from the input signal Ei at the V_FIN level, the disconnection at the V_COM level, the ON input at the V_H level, and the OFF input at the V_L level.

External channel short circuit (3):
In order to detect a short circuit between external channels, the diagnosis unit B performs pulse diagnosis. The short circuit between external channels refers to a phenomenon in which a terminal 3 of a certain channel is short-circuited with a terminal 3 of another channel outside the module. The pulse diagnosis procedure is described below.

  It starts from the normal state (SW1 is off, SW2 is on, SW3 is off). The first switch means SW1 of the diagnosis unit B is operated from OFF to ON by the operation signal M1 from the diagnosis management means 101b. As a result, the voltage level of the terminal 3 of the diagnosis target channel becomes V_FIN. At this time, the input signal level of the other channel is measured. If there is no short circuit between channels, only the input signal level of the diagnosis target channel should be V_FIN, and the input signal levels of the other channels should be V_H or V_L levels.

  However, when the external channel is short-circuited, the input signal level of the short-circuited channel becomes V_FIN in synchronization with the change of the input signal level of the diagnosis target channel to V_FIN, and this detects a short-circuit abnormality between external channels. be able to.

  FIG. 2 is a waveform diagram for explaining an example of occurrence of a short circuit between external channels. (A) is an n-channel operation signal M1, which is turned on for a predetermined period from time t1, and turns on the n-channel first switch means SW1. (B) is an m-channel operation signal M1, which is turned on for a predetermined period from time t2 delayed from the on-time of the n-channel operation signal M1, and turns on the n-channel first switch means SW1.

  (C) is an n-channel input signal Ei without a short circuit between external channels, and the input signal level becomes V_FIN in synchronization with the operation signal M1 of (A) at time t1. (D) is an m-channel input signal Ei in which a short circuit between the n-channel and the channel has occurred, and at time t2, the level of the input signal becomes V_FIN in synchronization with the operation signal M1 in (B). At time t1, the level of the input signal becomes V_FIN in synchronization with the operation signal M1 in (A).

  In such a short-circuit detection between external channels by pulse diagnosis, the control device 101 detects the pulse diagnosis timing so that an input value is not erroneously detected by performing an input acquisition operation while the first switch means SW1 is turned on. Control so that it does not overlap the normal input acquisition operation.

Internal ON sticking (4) and internal OFF sticking (5):
In order to detect internal ON sticking and internal OFF sticking abnormality, the diagnosis unit C performs ON / OFF diagnosis. Internal ON sticking and internal OFF sticking means that the level of the input signal Ei is fixed to ON or OFF regardless of the level of the terminal 3 due to internal failure of the voltage reading means 101a, resistor R2, resistor R3, etc. of the control device 101. A phenomenon that appears to stick.

  The ON / OFF diagnosis starts from a normal state (SW1 is off, SW2 is on, and SW3 is off). First, in order to separate the outside of the module from the inside of the module, the second switch means SW2 common to multiple points is turned off by the second operation signal M2 from the diagnosis management means 101b.

  At that time, the input signals Ei of all the channels are at the V_COM level. Here, if there is a channel that is not at the V_COM level, it is determined that this channel is abnormally stuck on.

  Next, the third switch means SW3 of the diagnosis target channel is turned on by the third operation signal M3 of the diagnosis management means 101b. As a result, the level of the input signal Ei of the diagnosis target channel becomes V_FIN. Here, if there is a channel that does not reach the V_FIN level, this channel is determined to be OFF sticking abnormality.

  FIG. 3 is a waveform diagram illustrating an example of occurrence of internal ON fixation and internal OFF fixation. (A) is a second operation signal M2 common to multiple points, and the second switch means SW2 is turned off during a period from time t1 to time t2. (B) is an n-channel third operation signal M3, and the n-channel third operation signal M3 during the period t4 from the time t3 to the time t2 from the time t1 when the second switch means SW2 is turned off. The switch means SW3 is turned on.

  (C) is the level of the input signal Ei of the n channel fixed internally OFF, and does not become the V_FIN level including the period from the time t1 to the time t2, but maintains the V_COM level.

  (D) is the level of the input signal Ei of the n-channel with the internal ON fixed, and does not become the V_COM level including the period from time t1 to time t2, but maintains the V_FIN level.

Internal channel short circuit (6):
In order to detect a short circuit abnormality between internal channels, the diagnosis unit C performs ON / OFFF diagnosis. The internal channel short-circuit is a point until the input signal Ei is input to the control device 101 from the third switch means SW3 of a certain channel, and the input signal Ei from the third switch means SW3 of the other channel to the control device 101. This refers to the phenomenon of short-circuiting with the location until input.

  In the state where the second switch means SW2 is turned off and the third switch means SW3 of the diagnosis target channel is turned on, the input signal level of the other channel is measured. If there is no short circuit between internal channels, only the input signal level of the diagnosis target channel should be V_FIN, and the input signal levels of the other channels should be VCOM levels.

  However, when the internal channel is short-circuited, the input signal level Ei of the counterpart channel becomes the V_FIN level in synchronization with the change of the input signal level Ei of the diagnosis target channel to V_FIN. Thereby, a short circuit between internal channels can be detected.

  FIG. 4 is a waveform diagram for explaining an example of occurrence of a short circuit between internal channels. (A) is a multipoint common second operation signal M2, which turns off the multipoint common second switch means SW2 during a period from time t1 to time t2 and from time t3 to time t4.

  (B) is an n-channel third operation signal M3, and an n-channel third switch during a period from time t5 to time t6 from time t1 to time t2 when the second switch means SW2 is turned off. The means SW3 is turned on.

  (C) is the m-channel third operation signal M3, and the m-channel third switch during the period from the time t7 to the time t8 during the time t4 from the time t3 when the second switch means SW2 is turned off. The means SW3 is turned on.

  (D) is the level of the normal n-channel input signal Ei, and changes to the V_FIN level in the period from time t5 to time t6 in synchronization with the operation signal M3 in (B).

  (E) is the level of the input signal Ei of the m channel that caused a short circuit between the n channel and the internal channel, and changes to the V_FIN level in the period from time t7 to time t8, and from time t5 before that to time t6. During the period, the level changes to the V_FIN level in synchronization with the level change of the n-channel input signal Ei.

  In the ON / OFFF diagnosis for detecting internal ON fixation, internal OFF fixation, and internal channel short circuit, the control device 101 is turned on so that the input acquisition operation is not performed while the second switch means SW2 is turned off. Control is performed so that the / OFF diagnosis timing does not overlap with the normal input acquisition operation.

  In the input module of the present invention, the operation signal M1 of the first switch means SW1 used in the pulse diagnosis can be changed other than the form shown in FIG. In the input module of the present invention, when the first switch means SW1 is turned on in pulse diagnosis, the voltage at the terminal 3 changes to V_FIN, which may affect the plant-side device that turns the input switch SW0 on and off. In such a case, it is possible to make adjustments such as shortening the ON time of the operation signal M1 or extending the period for turning on the operation signal M1.

  The operation signals M2 and M3 can be changed in addition to the forms shown in FIGS. In the input module of the embodiment, every time the ON / OFF diagnosis of one channel is performed, the second switch means SW2 is turned off → on → off, but the ON / OFF diagnosis of all channels is performed while SW2 is turned off → on. It is also possible to do this.

  In the embodiment, an example has been described in which two levels of the input signal Ei of each channel are measured one point at a time. However, it is possible to increase the speed by using a multi-point input comparator and improve the measurement performance. is there.

  Since the pulse diagnosis and the ON / OFF diagnosis employed in the input module of the present invention are independent from each other, it is possible to execute only one diagnosis. If only the ON / OFF diagnosis is executed, the first diagnostic element Q1 and the second diagnostic element Q2 are not necessary. Furthermore, when performing pulse diagnosis, the second diagnostic element Q2 may be omitted.

  Further, when the pulse diagnosis is executed with SW0 turned on, the first and second diagnostic elements Q1, Q2 may be omitted.

  In the embodiment, the application target of the input module of the present invention has been described as the contact information input unit of the safety control system. However, the present invention is not limited to this, and is generally applied to input modules that require reliability. Can do.

  In the embodiment, the input switch SW0 is shown in the form of a mechanical contact. However, the present invention is not limited to this, and electronic switch means such as a semiconductor can also be employed.

  In the above description, the disconnection, the short circuit, the pulse diagnosis, and the ON / OFF diagnosis are individually described. However, these diagnoses may be performed independently or in any combination.

It is a functional block diagram which shows one Embodiment of the input module to which this invention is applied. It is a wave form diagram explaining the example of generation | occurrence | production of the short circuit between external channels. It is a wave form diagram explaining the example of generation | occurrence | production of internal ON fixation and internal OFF fixation. It is a wave form diagram explaining the example of generating of a short circuit between internal channels. It is a functional block diagram which shows the general structural example of the conventional input module. 6 is a table in which wiring abnormalities that may occur when the circuit configuration of FIG. 5 is taken are classified.

Explanation of symbols

20 External power supply 100 Multi-point input module 101 Controller 101a Voltage reading means 101b Diagnosis management means SW0: Input switch L1, L2 Field wiring Q1 First diagnosis element Q2 Second diagnosis element SW1 First switch means SW2 Second switch means SW3 Second switch means 3 switch means R1 current detection resistor R2, R3 second current detection resistor

Claims (4)

The external power supply and the contacts of the input switches of all channels via field wiring are externally connected. Inside, one of the external power supplies is one of the contacts of the input switches of all the channels, and the other of the external power supplies is common And the other contact of the input switches of all channels is connected to the common potential via the first current detection resistors of all channels, and the voltage across the terminals of the first current detection resistors of all channels is In an input module comprising voltage readout means for monitoring,
  First switch means connected between the contact points of the input switches of all the channels and normally operated off;
  A second switch means that is normally turned on, and simultaneously connects the other of the contact points of the input switches of all the channels to the second current detection resistors of all the channels that give input signals to the voltage reading means;
  Diagnostic management means for outputting a first operation signal for operating on / off of the first switch means and a second operation signal for operating on / off of the second switch means;
With
  The diagnosis management means sequentially turns on the first switch means for each diagnosis target channel with the second switch means turned on at the same time, and is generated in the second current detection resistor during the operation period. The input signal level of the channel other than the diagnosis target channel is monitored via the voltage reading means, and the channel whose input signal level indicates the voltage level of the external power supply is short-circuited to the diagnosis target channel outside the input module. An input module characterized by diagnosing a short circuit abnormality between external channels. The diagnosis management means sequentially turns on the first switch means for each diagnosis target channel while the second switch means are simultaneously turned off, and is generated in the second current detection resistor during the operation period. The input signal level of a channel other than the diagnosis target channel to be monitored is monitored via the voltage reading means, and the channel whose input signal level indicates a voltage level other than the common potential is fixed to the ON side inside the input module. The input module according to claim 1, wherein the input module is diagnosed as having an internal ON sticking abnormality. The diagnosis management means sequentially turns on the first switch means for each diagnosis target channel with the second switch means turned on at the same time, and generates the second current detection resistor during the operation period. The input signal level other than the channel to be diagnosed is monitored via the voltage reading means, and the channel in which the input signal level does not become the voltage level of the external power supply is fixed to the off side inside the input module, internal OFF The input module according to claim 1, wherein the input module is diagnosed as a sticking abnormality. Provided with a third switch means which is operated by a third operation signal output from the diagnosis management means and connects one of the external power supplies to the second current detection resistors of all the channels, which is normally operated off;
  The diagnosis management means sequentially turns on the third switch means for each diagnosis target channel with the second switch means turned on at the same time, and generates the second current detection resistor during the operation period. The input signal level other than the diagnosis target channel is monitored via the voltage reading means, and a channel whose input signal level indicates the voltage level of the external power supply is synchronized with the ON operation of the diagnosis target channel inside the input module. The input module according to claim 1, wherein the input module is diagnosed as being short-circuited between the internal channels and being short-circuited with the channel to be diagnosed.

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