JP2012252483A - I/o module and duplex system using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an I/O module that prevents malfunctioning of another I/O module due to glitch caused by a voltage drop that occurs as charging current of a bypass capacitor or circuit current flows in a signal input line when an I/O module is inserted in a connector.SOLUTION: The voltage of electric power supplied from a connector is monitored so that a bypass capacitor or a circuit is connected when the electric power is supplied and the bypass capacitor or the circuit is cut off when the electric power is not supplied. Even when a signal input line is connected before an electric power line, as no excess current flows in the signal input line, glitch does not occur.

Description

  The present invention relates to an I / O module that does not generate a glitch when it is connected to a system by fitting a connector, and more particularly to an I / O module suitable for use in a duplex system.

  In the process control system, the process amount is taken in via the I / O module, and the control amount is output to the process. FIG. 5 shows a configuration of a duplexed I / O module capable of online maintenance.

  In FIG. 5, reference numeral 10a denotes an I / O module, which includes an input circuit 11a, a bypass capacitor 12a connected to the power supply terminals VD and COM of the input circuit 11a, and a connector 13a. The input circuit 11a includes a level detection unit 14a and diodes 15a and 16a connected between the input terminal of the level detection unit 14a and one power supply terminal and between the input terminal and the other power supply terminal. Since the power supply terminal and the input terminal of the level detector 14a are the same as the power supply terminals VD and COM of the input circuit 11a and the input terminal SIG, the diodes 15a and 15b are connected between the input terminal SIG and the power supply terminal VD of the input circuit 11a and the input terminal SIG. Connected between power supply terminals COM. The diodes 15a and 16a are inserted for the purpose of electrostatic protection.

  The contacts of the connector 13a are connected to the power supply terminals VD and COM and the input terminal SIG of the input circuit 11a. The I / O module 10 a operates with power supplied from the external power supply line 20, and a signal is input through the signal input line 21.

  Reference numerals 20, 21, and 22 denote an external power supply line, a signal input line, and a common potential point line, respectively, and these lines 20 to 22 are connected to the connector 23. Hereinafter, the external power supply line 20 and the common potential point line 22 are collectively referred to as a power supply line.

  The power supply terminals VD and COM of the input circuit 11a and the input terminal SIG are connected to the power supply lines 20 and 22 and the signal input line 21 via connectors 13a and 23, respectively. Although the connectors 13a and 23 are originally fitted, they are separated in this figure.

  Reference numeral 10b denotes an I / O module, and the I / O module 10a constitutes a duplex system. The I / O module 10b has the same configuration as the I / O module 10a, and includes an input circuit 11b, a bypass capacitor 12b, and a connector 13b. The input circuit 11b includes a level detection unit 14b and diodes 15b and 16b connected between the input terminal and the power supply terminal of the level detection unit 14b. The I / O module 10 b operates with an external power supply supplied from the power supply lines 20 and 22, and a signal is input from the signal input line 21.

  The connector 24 is connected to the power supply lines 20 and 22 and the signal input line 21 and is engaged with the connector 13b. The power supply lines 20 and 22 and the power supply terminals VD and COM of the input circuit 11b, the signal input line 21 and the input terminal SIG are connected through connectors 24 and 13b.

  In such a configuration, when the connectors 23 and 13a are fitted together, the I / O module 10b operates as a control side I / O module, and the I / O module 10a operates as a standby side I / O module. When an abnormality occurs in the control side I / O module 10b, the standby side I / O module 10a operates as a control side I / O module.

  Further, since the I / O module 10a, which is the standby I / O module, is not operating, even if the connectors 23 and 13a are disconnected, the system operation is not hindered. Therefore, the I / O module 10a can be extracted and replaced while the system is operating. That is, online maintenance is possible.

  The process control system must be run for 24 hours to ensure system continuity. For this reason, by using I / O modules 10a and 10b for redundancy, when a failure occurs in one I / O module, it is possible to seamlessly switch to the other I / O module and to operate the system while operating. I / O modules that have been changed can be exchanged.

  FIG. 7 shows the configuration of another duplexed I / O module. The same elements as those in FIG. 5 are denoted by the same reference numerals and description thereof is omitted.

  In FIG. 7, reference numerals 30a and 30b denote duplicated I / O modules, each of which includes connectors 13a and 13b and input circuits 11a and 11b. The I / O module 30a is connected to the power supply lines 20 and 22 and the signal input line 21 via the connectors 13a and 23, and the I / O module 30b is connected to these lines via the connectors 13b and 24. In this figure, connectors 13a and 23 are disconnected.

  Compared with FIG. 5, the I / O modules 30a and 30b are different in that bypass capacitors 12a and 12b are not incorporated. The operation is the same as in FIG.

  Patent Document 1 describes a process control controller that can insert and remove modules in a live line state. In Patent Document 1, a power connector and a communication connector are separated, and power is supplied to a plurality of I / O modules via a power short piece and a GND short piece.

JP 2000-330603 A

However, such I / O modules have the following problems.
FIG. 6 shows a state where the connectors 13a and 23 are fitted together and the I / O module 10a having the configuration shown in FIG. Since each contact of the connectors 13a and 23 has the same length, which contact is connected changes depending on the inclination of the connector at the time of insertion. The order of the connected contacts cannot be predicted or controlled.

  As shown in FIGS. 6A to 6C, at time t1 to t3, the contact of the common potential point line 22, the contact of the signal input line 21, and the contact of the external power supply line 20 are in this order in the I / O module. 10a. Since the input terminal SIG of the input circuit 11a and the signal input line 21 are connected at time t2, if the signal level on this line is high, the input signal voltage of the input circuit 11a is as shown in (D). Transition to a high level at time t2.

  At time t2, since power is not supplied to the input circuit 11a from the outside, the diode 15a is turned on. For this reason, as shown in (F), a large current flows from the signal input line 21 to the diode 15a. Since the bypass capacitor 12a is charged by this current, the power supply voltage of the input circuit 11a rises as shown in (E).

  When power is supplied to the input circuit 11a at time t3, the power supply voltage of the input circuit 11a further increases and eventually stabilizes. The reason why the voltage gradually increases in (D) and (E) is because the bypass capacitor 12a is charged.

  As shown in (F), a large current flows through the diode 15 a at time t 2, and this current is supplied from the signal input line 21. Due to this current, a voltage drop occurs in the signal input line 21, and a glitch that changes the input signal voltage of the input circuit 11 b connected to the same signal input line 21 occurs as shown in (G). Therefore, there is a problem that the input circuit 10b detects this change and outputs an error signal.

  Such a malfunction also occurs in the I / O module of FIG. 7 that does not include a bypass capacitor.

  FIG. 8 shows a state when the connectors 13a and 23 are engaged with each other in the I / O module having the configuration shown in FIG. As shown in (A) to (C), at time t4 to t6, the contact of the common potential point line 22, the contact of the signal input line 21, and the contact of the external power supply line 20 are connected to the I / O module 10a in this order. The Since the input terminal SIG of the input circuit 11a and the signal input line 21 are connected at time t5, if the signal level on this line is high, the input signal voltage of the input circuit 11a is as shown in (D). It becomes high at time t5 and the diode 15a is turned on.

  Since current is supplied from the diode 15a to the input circuit 11a, current flows through the diode 15a as shown in (F), and the power supply voltage of the input circuit 11a increases.

  Since the current flowing through the diode 15a is supplied from the signal input line 21, the current flows through the signal input line 21 to cause a voltage drop, and the input circuit 11b connected to the same signal input line 21 as shown in (G). The voltage at the input terminal changes and an error occurs. For this reason, the level detector 14b detects this change and outputs an error signal.

  As described above, depending on the connection order of the contact points of the connector, a current flows in the signal input line 21 and a voltage drop occurs, and a glitch occurs in the input voltage of the input circuit 11b connected to the same signal input line 21. There is a problem that an erroneous signal is rarely generated. When this occurs, there is a problem that the system shuts down in the worst case.

  The invention described in Patent Document 1 separates the power connector and the communication connector, and supplies power to a plurality of I / O modules via the power short piece and the GND short piece, so that the order of connection can be controlled. . However, there is a problem that the structure of the mount base is complicated, and in order to supply power to the module, a short piece must be connected, and the operation becomes complicated.

  An object of the present invention is to realize an I / O module that prevents a current from flowing through a signal input line at the time of connection and does not generate a glitch.

In order to achieve such a problem, the invention according to claim 1 of the present invention is:
In an I / O module that is connected to a power supply line and a signal input line via a connector, is supplied with power from the power supply line, processes a signal on the signal input line, and outputs a corresponding signal.
An input circuit in which a signal on the signal input line is input and processed, and a diode is connected between the input terminal and the power supply terminal;
A bypass capacitor;
A switch for connecting and disconnecting the bypass capacitor to the power supply terminal of the input circuit;
The voltage of the power supplied through the connector is monitored, the switch is controlled, and when the power is supplied, the bypass capacitor is connected to the power supply terminal of the input circuit, and the power is supplied. Otherwise, a power supply voltage detector that disconnects the bypass capacitor from the power supply terminal of the input circuit;
Is provided. When an I / O module is inserted, no overcurrent flows through the signal input line, so that no glitch occurs.

The invention according to claim 2
In an I / O module that is connected to a power supply line and a signal input line via a connector, is supplied with power from the power supply line, processes a signal on the signal input line, and outputs a corresponding signal.
An input circuit in which a signal on the signal input line is input and processed, and a diode is connected between the input terminal and the power supply terminal;
A switch for conducting or blocking a path for supplying power to the input circuit;
The voltage of the power supplied via the connector is monitored, the switch is controlled, and when the power is supplied, the path for supplying the power to the input circuit is conducted, and the power is not supplied. And a power supply voltage detection unit for cutting off the path,
Is provided. When an I / O module is inserted, no overcurrent flows through the signal input line, so that no glitch occurs.

The invention described in claim 3
Two I / O modules according to claim 1 or 2 are used, one being a control-side I / O module and the other being a standby-side I / O module. Since no glitch is generated when the standby I / O module is inserted, the control I / O module does not detect an error signal.

The present invention has the following effects.
According to the first, second, and third aspects of the present invention, the voltage of the power supplied through the connector is monitored, and when the power is supplied, the bypass capacitor is connected to the power supply terminal of the input circuit, The path for supplying power is made conductive, the bypass capacitor is disconnected when power is not supplied, and the path for supplying power to the input circuit is cut off. Also, a duplex system was configured using this I / O module.

  When the I / O module is inserted into the connector, the signal input line is connected before the power supply line, the diode is turned on, and a large current can be prevented from flowing through the signal input line. For this reason, no glitch caused by a voltage drop is generated in the signal input line, and there is an effect that other I / O modules connected to the same signal input line do not malfunction.

  Further, in the case of a duplex system, no glitch is generated when the standby side I / O module is inserted, so that the control side I / O module does not malfunction. For this reason, there is an effect that a duplex system with high reliability can be constructed.

It is the block diagram which showed one Example of this invention. It is a characteristic view for demonstrating the operation | movement of FIG. 1 Example. It is the block diagram which showed the other Example of this invention. 3 is a characteristic diagram for explaining the operation of the embodiment. It is a block diagram of the conventional duplexed I / O module. 5 is a characteristic diagram for explaining the operation of the conventional example. It is a block diagram of the conventional duplexed I / O module. 7 is a characteristic diagram for explaining the operation of the conventional example.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of an I / O module according to the present invention. This embodiment corresponds to the conventional example of FIG. The same elements as those in FIG. 5 are denoted by the same reference numerals and description thereof is omitted.

  In FIG. 1, reference numeral 40a denotes an I / O module, which includes an input circuit 11a, a bypass capacitor 12a, a connector 13a, a switch 41a, and a power supply voltage detector 42a. The input circuit 11a includes a level detection unit 14a and diodes 15a and 16a connected between the input terminal of the level detection unit 14a, a power supply terminal, and a common potential point. Since the power supply terminal and the input terminal of the input circuit 11a and the level detection unit 14a are common, the diodes 15a and 15b are connected between the input terminal SIG of the input circuit 11a and the power supply terminals VD and COM.

  One end of the bypass capacitor 12a is connected to the power supply terminal VD of the input circuit 11a, and the other end is connected to one end of the switch 41a. The other end of the switch 41a is connected to the power supply terminal COM of the input circuit 11a. By operating the switch 41a, the bypass capacitor 12a can be connected to and disconnected from the power supply terminal of the input circuit 11a.

  The input circuit 11a is connected to the power supply lines 20 and 22 and the signal input line 21 via connectors 13a and 23. When the connectors 13a and 23 are fitted, power is supplied to the input circuit 11a from the power supply lines 20 and 22, and a signal is input from the signal input line 21. In FIG. 1, connectors 13a and 23 are in a disconnected state.

  When the connectors 13a and 23 are engaged, power is supplied to the input circuit 11a. The input circuit 11a detects the signal level on the signal input line 21, and transmits the detection result to the host system. Note that the configuration for transmitting to the host system is not directly related to the present invention, and thus the description is omitted.

  The power supply voltage supplied through the connector 13a is input to the power supply voltage detection unit 42a. The power supply voltage detector 42a monitors the input power supply voltage, and controls on / off of the switch 41a based on the monitoring result. That is, the power supply voltage detector 42a turns on the switch 41a when power is supplied via the connector 13a, connects the bypass capacitor 12a to the power supply terminal of the input circuit 11a, and turns off the switch 41a when power is not supplied. To separate the bypass capacitor 12a. By monitoring the voltage at the contact of the connector 13a, it can be determined whether or not power is being supplied.

  Reference numeral 40b denotes an I / O module, which includes an input circuit 11b, a bypass capacitor 12b, a connector 13b, a switch 41b, and a power supply voltage detector 42b. Further, diodes 15b and 16b are connected to the input circuit 11b between the input terminal SIG of the input circuit 11b and the power supply terminals VD and COM.

  The I / O module 40b has the same configuration as the I / O module 40a. That is, the input circuit 11b detects the signal level on the signal input line 21, and transmits the detection result to the host system. The power supply voltage detector 42b monitors the voltage of the power supplied from the connector 13b. When this power is supplied, the switch 41b is turned on to connect the bypass capacitor 12b to the power supply terminal of the input circuit 11b. If not, the switch 41b is turned off to disconnect the bypass capacitor 12b. In FIG. 1, the connectors 13b and 24 are in a mated state.

  When the connectors 13a and 23 are fitted together, a duplex system is configured by the I / O modules 40a and 40b. That is, the I / O module 40b operates as a control side I / O module, and the I / O module 40a operates as a standby side I / O module. Since the standby side I / O module is not related to the operation of the system, the connector 23 and 13a can be disconnected and repaired or replaced while the system is in an operating state (live line state).

  Next, the operation of this embodiment will be described with reference to FIG. FIG. 2 is a waveform diagram showing the state of each signal at the moment when the connectors 13a and 23 are fitted together. As shown in FIG. 1, it is assumed that the switch 41a is off before the connectors 13a and 23 are fitted together.

  2A to 2C are diagrams showing the connection state of the contacts of the common potential point line 22, the signal input line 21, and the external power supply line 20. Since the lengths of the contact points of the connectors 13a and 23 are equal, the order of connection differs depending on the inclination of the connector when fitted. For this reason, the order in which the contacts are connected cannot be predicted or controlled. In FIG. 2, the common potential point line 22, the signal input line 21, and the external power supply line 20 are connected in this order at times t10 to t12.

  (D) is a waveform diagram showing the transition of the voltage of the input terminal SIG in the input circuit 11a. Since the signal input line 21 is connected to the input terminal SIG at time t11, the voltage of the input terminal SIG becomes high level.

  (E) is a waveform diagram showing the transition of the power supply voltage of the input circuit 11a. Since the input terminal voltage of the input circuit 11a rises at time t11, the diode 15a is turned on. For this reason, the power supply voltage of the input circuit 11a rises at time t11.

  (F) is the state of the switch 41a. As shown in (E), the power supply voltage of the input circuit 11a rises at time t11, but since the power is not supplied through the connector 13a, the switch 41a maintains the OFF state.

  (G) is a transition diagram of the current flowing through the diode 15a. Since the switch 41a is off at time t11, the bypass capacitor 12a is disconnected from the power supply terminal of the input circuit 11a. Therefore, the diode 15a is turned on at time t11, but almost no current flows.

  At time t12, the contact of the external power supply line 20 is connected, and power is supplied from the connector 13a. As shown in (E), the power supply voltage of the input circuit 11a gradually rises to the voltage value of the external power supply. Since power is supplied from the connector 13a, the power supply voltage detector 52a turns on the switch 41a. The bypass capacitor 12a is connected to the power supply terminals VD and COM of the input circuit 11a. However, since the charging current of the bypass capacitor 12a is supplied from an external power supply, almost no current flows through the diode 15a as shown in FIG. .

  (H) is a transition diagram of the input voltage of the input circuit 11b. As shown in (G), since almost no current flows through the diode 15a, no overcurrent flows through the signal input line 21 and no glitch is generated. For this reason, even if the I / O module 40a is inserted, the input voltage of the input circuit 11b does not change.

  FIG. 3 shows another embodiment of the present invention. This embodiment corresponds to the conventional example of FIG. The same elements as those in FIGS. 1 and 7 are denoted by the same reference numerals and description thereof is omitted. Only differences from FIG. 1 will be described.

  In FIG. 3, reference numeral 50a denotes an I / O module, which includes an input circuit 11a, a connector 13a, a switch 51a, and a power supply voltage detector 52a. The power supply terminal VD of the input circuit 11a is connected to the connector 13a, and the power supply terminal COM is connected to one end of the switch 51a. The other end of the switch 51a is connected to a common potential point. The power supply voltage detector 52a monitors the power supply voltage supplied from the external power supply line 20. When power is supplied, the switch 51a is turned on to turn on the power supply path to the input circuit 11b, and the power is supplied. Otherwise, the switch 51a is turned off to block this path.

  Reference numeral 50b denotes an I / O module, which includes an input circuit 11b, a connector 13b, a switch 51b, and a power supply voltage detector 52b. The I / O module 50b has the same configuration as the I / O module 50a.

  Next, the operation of this embodiment will be described with reference to FIG. In addition, (A)-(H) represent the waveform of the same point as FIG. As shown in FIGS. 4A to 4C, the common potential point line 22, the signal input line 21, and the external power supply line 20 are connected to the input circuit 11a at times t13, t14, and t15, respectively.

  At time t14, as shown in (D), the voltage of the input terminal SIG of the input circuit 11a transitions to a high level. For this reason, the diode 15a is turned on, and the power supply voltage of the input circuit 11a rises as shown in (E). However, since no power is supplied from the connector 13a, the switch 51a continues to be kept off as shown in FIG. Since the power supply path of the input circuit 11a is cut off, no power supply current flows through the input circuit 11a. For this reason, as shown in (G), almost no current flows through the diode 15a.

  When external power is supplied via the connector 13a at time t15, the power supply voltage of the input circuit 11a rises as shown in (E). Since power is supplied from the connector 13a, the switch 51a is turned on, and a power supply current is supplied to the input circuit 11a. Since the operating current of the input circuit 11a is supplied from an external power supply, the current flowing through the diode 15a becomes almost zero as shown in (G).

  Also in this case, since no current flows through the diode 15a, no overcurrent flows through the signal input line 21. For this reason, no glitch occurs and the voltage at the input terminal of the input circuit 11b does not fluctuate as shown in (H).

  1 and 3, the I / O modules 40a and 40b and 50a and 50b have the same configuration, but they do not necessarily have to have the same configuration. The configurations may be different as long as they are connected to the same signal input line. In addition, the I / O module that constitutes the duplex system is not necessarily required.

  In these embodiments, the I / O modules 40a, 40b, 50a, and 50b have a built-in level detection unit that detects the level of the input signal and outputs the result. However, the present invention is not limited to this configuration. Not. Any configuration may be used as long as a voltage signal is input, the voltage signal is processed, and a signal corresponding to the voltage signal is output.

  In the embodiment shown in FIG. 1, a switch is inserted in series with the bypass capacitor 12a (12b). In the embodiment shown in FIG. 3, the switch is inserted in series with the input circuit 11a (11b). Never happen. In the embodiment shown in FIG. 1, the bypass capacitor 12a (12b) is connected to and disconnected from the power supply terminal of the input circuit 11a (11b). In the embodiment shown in FIG. 3, the power supply path to the input circuit 11a (11b) is turned on and off. If it is.

  Furthermore, a mechanical switch, a semiconductor switch, a transistor, or the like can be used as the switches 41a, 41b, 51a, and 51b.

11a, 11b Input circuit 12a, 12b Bypass capacitor 13a, 13b, 23, 24 Connector 15a, 16a, 15b, 16b Diode 20 External power supply line 21 Signal input line 22 Common potential point line 40a, 40b, 50a, 50b I / O module 41a, 41b, 51a, 51b Switch 42a, 42b, 52a, 52b Power supply voltage detector

Claims (3)

In an I / O module that is connected to a power supply line and a signal input line via a connector, is supplied with power from the power supply line, processes a signal on the signal input line, and outputs a corresponding signal.
An input circuit in which a signal on the signal input line is input and processed, and a diode is connected between the input terminal and the power supply terminal;
A bypass capacitor;
A switch for connecting and disconnecting the bypass capacitor to the power supply terminal of the input circuit;
The voltage of the power supplied through the connector is monitored, the switch is controlled, and when the power is supplied, the bypass capacitor is connected to the power supply terminal of the input circuit, and the power is supplied. Otherwise, a power supply voltage detector that disconnects the bypass capacitor from the power supply terminal of the input circuit;
An I / O module comprising: In an I / O module that is connected to a power supply line and a signal input line via a connector, is supplied with power from the power supply line, processes a signal on the signal input line, and outputs a corresponding signal.
An input circuit in which a signal on the signal input line is input and processed, and a diode is connected between the input terminal and the power supply terminal;
A switch for conducting or blocking a path for supplying power to the input circuit;
The voltage of the power supplied via the connector is monitored, the switch is controlled, and when the power is supplied, the path for supplying the power to the input circuit is conducted, and the power is not supplied. And a power supply voltage detection unit for cutting off the path,
An I / O module comprising:   3. A duplex system using two I / O modules according to claim 1 or 2, wherein one is a control side I / O module and the other is a standby side I / O module.

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