JP2011164966A - Wiring system of multiple proximity sensors and plc and relay box used for the system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce wiring labor hour and wiring cost by dispensing with drawing of wiring from proximity sensors to a PLC, even when the number of proximity sensors with specific function is increased, and to maintain the wiring number to the PLC at a minimum wiring number. <P>SOLUTION: The system includes: a plurality of proximity sensors 2 each of which outputs detection signal and specific signal; the PLC 3 which respond to the signals from each proximity sensor 2; and a relay box 4 which relays and transmits the signals from each proximity sensor 2 to the PLC 3. The relay box 4 includes: a plurality of transmission wire connecting terminals 4a which individually connect a plurality of transmission wires 6 connected for each proximity sensor 2 to transmit the signals thereof; a bus wire connecting terminal 4b which connects a single bus wire 7 for network communication with the PLC 3; and an internal processing circuit 4c which performs processing to convert a plurality of signals applied to each transmission wire connecting terminal 4a from each proximity sensor 2 through the transmission line 6 into a signal form of network communication and to output the resulting signals to the single bus wire connecting terminal 4b. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a system for wiring-connecting a plurality of proximity sensors and a PLC (programmable controller), and in particular, wiring a proximity sensor having a specific function such as a self-diagnosis function in addition to the proximity detection of a detection target to the PLC. It relates to the system to be connected.

  The PLC is used by being incorporated in a control system that controls a large number of production machines. In addition to a CPU that controls the entire system, a program ROM that stores a ladder program that is a user program, a work RAM that the CPU uses for work, and other input devices such as sensors attached to various production devices and equipment devices Are provided, and an I / O unit for outputting a control output to an output device such as an actuator or a motor is provided. Devices such as sensors and motors connected to the I / O unit are constructed and arranged by the user in accordance with the production machine to constitute a user circuit device.

  The proximity sensor is used as one of the input devices in the PLC as a sensor that can detect the presence or movement of the detection target by replacing the detection target with an electric signal in a non-contact state with the detection target. There are also many uses.

  Such proximity sensors include, for example, a high-frequency oscillation type in which a detection target is a metal, and a capacitance method that can be detected even if the detection target is not a metal. Such proximity sensor signal output forms include analog output and on / off output. The proximity sensor is used as one of input devices that detect and input the state of the control device to the PLC in Patent Document 1, for example.

  In the proximity sensor described above, a detection signal is output from its output terminal depending on whether or not a detection target is detected. In this case, the output terminal of the proximity sensor is connected to the input terminal of the PLC, for example. The transmission wiring between the output terminal of the proximity sensor and the input terminal of the PLC includes at least two transmission wirings related to power supply and one transmission wiring related to transmission of detection signals of the proximity sensor.

  When the self-diagnosis and other specific functions are added to the proximity sensor, in addition to the detection signal transmission wiring (detection signal transmission wiring), a wiring for transmitting a signal related to the specific function It is necessary to add (specific signal transmission wiring). An example of a proximity sensor for self-diagnosis is Patent Document 2. When such a proximity sensor with a specific function such as self-diagnosis is connected to the input terminal of the PLC, it is necessary to additionally connect a transmission wiring for transmitting a specific function signal to the input terminal of the PLC.

JP2002-076871 JP2008-301158

  In the proximity sensor to which the specific function is added, in addition to the normal transmission wiring, it is necessary to wire the transmission wiring for the specific function between the proximity sensor and the PLC. As a result of routing a large number of wires to the PLC at the location, in addition to increasing the wiring work for the wiring of the specific function signal transmission wiring, it is required to secure a large number of wiring laying spaces, and the wiring cost is high. Issues such as increasing will arise.

  Therefore, the problem to be solved by the present invention is that even if the number of proximity sensors with a specific function increases, it is not necessary to route the wiring from these proximity sensors to the PLC, thereby reducing the wiring laying space. At the same time, the number of wirings to the PLC is maintained at the minimum number of wirings, thereby making it possible to reduce wiring labor and wiring costs.

  A wiring system of a plurality of proximity sensors and a PLC according to the present invention includes a plurality of proximity sensors that output at least two signals, a PLC that responds to a signal from each of the proximity sensors, and a signal from each of the proximity sensors that is a PLC. A relay box for relay transmission, and the relay box is connected to each proximity sensor and a plurality of transmission wiring connection terminals for individually connecting a plurality of transmission wirings for transmitting respective signals, and a PLC A network communication signal format consisting of a bus wiring connection terminal for connecting a single bus wiring for network communication between each other and a plurality of signals applied to each transmission wiring connection terminal from each of the proximity sensors via the transmission wiring. And a processing circuit for performing output processing to a single bus wiring connection terminal.

  According to the wiring system of the present invention, it is not necessary to connect the transmission wiring of each of the plurality of proximity sensors to the PLC, and the transmission wiring of each of the proximity sensors can be connected to the PLC only by connecting to the transmission wiring connection terminal of the relay box. As a result, it is only necessary to connect a single network wiring to the network wiring connection terminal of the relay box. As a result, the signal transmission wiring is routed from each proximity sensor to the PLC as in the conventional case. Compared to the case where the connection is made, the wiring labor can be greatly reduced, and it is no longer necessary to route a large number of wires from the proximity sensor position near the detection target to the PLC at a remote position. Space for laying up to the PLC is also unnecessary, and the wiring cost can be greatly reduced.

  Preferably, one of the two signals of the proximity sensor is a detection signal corresponding to detection of the detection target, and the other is a specific signal for adding a specific function to the proximity sensor. As this specific signal, for example, there is a self-diagnosis signal.

  According to the present invention, the number of transmission lines for transmitting signals from a plurality of proximity sensors to the PLC is different from that for normal sensor signal transmission lines in addition to signal transmission lines related to specific functions such as a self-diagnosis function. In the proximity sensor increased by several minutes, the transmission wires of each of the plurality of proximity sensors are connected together to the relay box, while the transmission signals are collectively transmitted through the single network wiring from the relay box to the PLC. As a result, it is no longer necessary to route a large number of transmission lines from a plurality of proximity sensors to the PLC (reducing wiring), it is not necessary to secure a space for laying these transmission lines, and wiring work to the PLC is simplified. Wiring costs can be greatly reduced.

FIG. 1 is a diagram illustrating a wiring system including a plurality of proximity sensors, a relay box, and a PLC according to an embodiment of the present invention. FIG. 2 is an enlarged view showing a main part of the system shown in FIG. 1 in detail. FIG. 3A is a diagram illustrating waveforms of the sensor output signal and the self-diagnosis output signal, and FIG. 3B is a diagram illustrating a format of the network communication signal.

Hereinafter, a wiring system according to an embodiment of the present invention will be described with reference to the accompanying drawings. Referring to FIG. 1, the wiring system 1 includes a plurality of proximity sensors 2, a PLC 3, and a relay box 4 that is interposed between them and relay-connects the proximity sensor 2 to the PLC 3.
The proximity sensor 2 can output the detection signal S1 of the detection target 5 and the specific signal S2 such as self-diagnosis to the relay box 4. The proximity sensor 2 is supplied with power from the PLC 3 via the relay box 4.

  The transmission wiring 6 from the output terminal 2a of each proximity sensor 2 to the sensor relay input terminal 4a of the relay box 4 is an individual wiring between each proximity sensor 2 and the relay box 4. The transmission wiring 6 includes two lines 6a and 6b for DC and 0V for receiving power, and two lines 6c and 6d for transmission of the detection signal S1 and the specific signal S2. For example, it can be configured in the form of a cable.

  The wiring 7 from the PLC relay terminal 4a of the relay box 4 to the input terminal 3a of the PLC 3 is a network wiring such as a device net, FL-NET, or MODBUS. For example, the network wiring 7 specifies two of the power supply DC and 0V wirings 7a and 7b for supplying power to the proximity sensor, and the detection signal S1 and the specific signal S2 from the proximity sensor 2 side. And one bus wiring 7c for transmitting via network communication in the format of If the communication format for transmitting this signal is a device network, for example, there is CAN which is an abbreviation for cable area network. This network wiring can also be configured in a cable format.

  As can be seen from FIG. 1, all of the transmission wires 6 of the plurality of proximity sensors 2 are connected to the relay box 4 and are not connected to the PLC 3. Accordingly, the relay box 4 is arranged in the vicinity of each of the plurality of proximity sensors 2 and all the transmission wirings 6 of the proximity sensors 2 are connected to the relay box 4, while the relay box 4 and the relay box 4 As a result of being able to connect the PLC 3 in the separated position with a single transmission wiring 7 as a cable, the wiring around the PLC 3 is greatly simplified.

  Referring to FIG. 2, the output terminal 2a of each proximity sensor 2 and the input terminal 4a of the relay box 4 are in the form of connectors, and the DC lines and signals from the proximity sensor 2 are transmitted by these connector-type terminals 2a and 4a. The wirings 6a-6d of the S1, S2 line and 0V line can be individually connected to the relay box 4 together. Further, the output terminal 4b of the relay box 4 and the input terminal 3a of the PLC 3 are in the form of connectors, and these connectors allow the wiring 7a-7c constituting the transmission wiring 7 to be bundled and connected by cable. .

  Regarding power supply to the proximity sensor 2, DC power is supplied from the PLC 3 to the relay box 4 via the DC line 7 a and the 0 V line 7 b in the network wiring 7, and further, the DC line in the transmission wiring 6 from the relay box 4. Power is supplied to the proximity sensor 2 via 6a and the 0V line 6b.

  On the other hand, the detection signal S1 and the specific signal S2 from the proximity sensor 2 are input to the relay box 4 via the signal lines 6c and 6d in the transmission wiring 6. In the relay box 4, the internal processing circuit 4 c converts the signals S 1 and S 2 into a signal format for network communication, and transmits the converted signal to the PLC 3 via the bus wiring 7 c in the network wiring 7.

  In this case, even when there are a plurality of proximity sensors 2 and the detection signal S1 and the specific signal S2 are respectively input from the proximity sensors 2 to the relay box 4, the processing circuit 4c of the relay box 4 has the proximity sensors 2 respectively. Each detection signal S1 and specific signal S2 can be collectively transmitted to the PLC 3 via the bus wiring 7c in the network wiring 7.

  Further, the relay box 4 also transmits a determination signal for allowing the PLC 3 to determine which proximity sensor 2 is the detection signal S1 or the specific signal S2.

  In the proximity sensor 2, as shown in FIG. 3A, a signal that changes to a high level (Hi) when the detection target is not detected and changes to a low level (Lo) when the detection target is detected is detected signal. If the specific signal S2 is a self-diagnosis signal, for example, as shown in FIG. 3B, when the proximity sensor state is normal, the high level (Hi) and the low level (Lo) are output. A signal whose potential is dynamically changed at a predetermined frequency and the potential is fixed at a low level (Lo) is output as a self-diagnosis signal S2 when an abnormality occurs. In addition, although FIG.3 (b) was a self-diagnosis signal as specific signal S2, it is not limited to this, You may apply to another specific signal. When FIG. 3B is used as a self-diagnosis signal, for example, when the transmission wiring is not disconnected in the self-diagnosis mode, the waveform of the self-diagnosis signal S2 has a high level (Hi) and a low level (Lo). It can be seen that there is no disconnection due to the dynamic change, and that the transmission wiring is disconnected when the waveform of the self-diagnosis signal S2 is fixed at the low level (Lo). From this, cable disconnection or the like can be detected.

  Further, a signal may be transmitted from the relay box 4 to the PLC 3 in the packet format for each proximity sensor 2. For example, in each packet, the detection signal S1 is transmitted as data 1 and the specific signal S2 is transmitted as data 2 as shown in FIG. The PLC 3 processes the data 1 and data 2 in the transmitted packet to obtain a detection signal S1 and a specific signal S2. And PLC3 controls a control object suitably from obtained signal S1, S2. In this case, a header can be added to data 1 and data 2 in the packet so that the proximity sensor 2 can be identified on the PLC 3 side. If the proximity sensor 2 is 1st to 4th, the data 1 and 2 of the 1st proximity sensor are transmitted following the 1st header, the data 1 and 2 of the 2nd proximity sensor are transmitted following the 2nd header, The data 1 and 2 of the third proximity sensor are transmitted following the third header, and the data 1 and 2 of the fourth proximity sensor are transmitted following the fourth header. In the PLC 3, it is possible to determine from which proximity sensor 2 the data is based on the header information, and perform necessary control on the detection target 5 corresponding to the proximity sensor 2.

  As described above, in this embodiment, the number of transmission lines for transmitting signals from the proximity sensor to the PLC is increased in addition to the transmission lines for the normal detection signal S1, and the transmission lines for the specific signal S2 such as the self-diagnosis function are increased. In the proximity sensor, the transmission wiring 6 of each of the plurality of proximity sensors 2 is connected to the relay box 4, while the transmission signal is transmitted from the relay box 4 to the PLC 3 through the single network wiring 7. It is no longer necessary to route a large number of transmission wires from a plurality of proximity sensors 2 to the PLC 3, and it is not necessary to secure a laying space for these transmission wires, and the wiring work to the PLC 3 is simplified and the wiring cost is greatly reduced. Can do.

1 Wiring system 2 Proximity sensor 3 PLC
4 Relay box 5 Detection target 6 Transmission wiring 7 Network wiring

Claims (3)

A plurality of proximity sensors that output at least two signals;
A PLC that responds to signals from each of the proximity sensors;
A relay box that relays signals from the proximity sensors to the PLC;
Including
The relay box has a single bus for network communication between a plurality of transmission wiring connection terminals individually connected to a plurality of transmission wirings connected to each proximity sensor and transmitting respective signals. A bus wiring connection terminal for connecting wiring, and a plurality of signals applied to each transmission wiring connection terminal from each proximity sensor via the transmission wiring to a signal format of network communication to convert to a single bus wiring A processing circuit for performing output processing on the connection terminal,
Wiring system characterized by that.   Among the two signals of the proximity sensor, one is a detection signal corresponding to detection of a detection target, and the other is a specific signal for adding a specific function to the proximity sensor. Item 4. The wiring system according to Item 1.   A relay box used in the wiring system according to claim 1 or 2, wherein a single bus wiring is used for network communication between a plurality of transmission wiring connection terminals for individually connecting the transmission wirings of the respective proximity sensors and the PLC. A single bus wiring connection by converting the signal applied to each transmission wiring connection terminal from each proximity sensor via the transmission wiring to each transmission wiring connection terminal into a signal format for network communication. A relay box including a processing circuit that performs output processing on the terminal.

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