JP4147430B2 - Programmable controller system - Google Patents

Description

  The present invention relates to a PLC system in which a plurality of programmable controllers (hereinafter referred to as PLCs) are connected via a network.

  When monitoring a plurality of PLCs connected to a network, there is a method of monitoring by directly connecting a computer (development support apparatus) having a monitoring function to the PLC to be monitored with a communication cable. However, this method is inconvenient because the computer must be moved to the vicinity of the PLC to be monitored.

  Thus, a technique is known in which a computer is connected to one PLC on the network and another PLC on the network is monitored via the PLC (see, for example, Patent Document 1).

  In the above-described known technology, when another PLC on the network (hereinafter referred to as a target PLC) is monitored via the PLC, even if a state in which communication between the computer and the target PLC cannot be performed occurs, It has been difficult to discover where an abnormality has occurred on the communication path with the target PLC. In particular, when the communication path extends over a plurality of networks, it is further difficult to investigate the cause of the abnormality.

  For example, in a system in which a personal computer (development support apparatus) is connected to a specific PLC (hereinafter referred to as a relay PLC) via a connection cable, and the relay PLC and the target PLC are connected via a network. When the user performs monitoring or parameter editing on the target PLC, the following operation procedure is taken.

  That is, first, as a first procedure, communication specifications (communication protocol, communication speed, etc.) between the personal computer and the target PLC are set, as a second procedure, online connection with the target PLC is performed, and as a third procedure, Monitor the target PLC and edit the parameters.

  At this time, the connection with the target PLC cannot be performed in the second procedure, and an error message such as “communication error” or “model is different” is displayed, or the target PLC monitor is displayed in the third procedure. In some cases, communication is interrupted, an error message such as “communication error” is displayed, and operation becomes impossible.

  The cause of such a problem is that there is a problem between the personal computer and the relay PLC, a problem between the relay PLC and the target PLC, a problem in the target PLC itself, etc. Is assumed.

  Here, problems between the personal computer and the relay PLC include (1) disconnection of the connection cable, wiring mistake, (2) error in the communication specification set on the personal computer side, and (3) communication port of the relay PLC. Misconfiguration, etc.

  Further, problems between the relay PLC and the target PLC include (1) disconnection of the connection cable in the communication path, (2) setting error in the routing table stored in advance in the PLC of the communication path, (3 ) Communication timeout associated with the communication load of the network on the communication path, etc.

Furthermore, problems with the target PLC itself include (1) when the target PLC is not the assumed PLC, (2) when the target PLC setting is changed or reset, and there is no communication response, and so on. it can.
JP 2000-47717 A

  In the conventional apparatus, by connecting to the PLC via the network, the user can perform monitoring, program editing, parameter setting, etc. of a plurality of PLCs without switching the physical cable connection. On the other hand, when communication is not possible via the network, there is a problem that it takes a very long time to investigate the cause because of the complexity of the network path or the variety of factor items.

  In particular, the routing mechanism for transferring the communication command to the target PLC is to set the routing table in advance on each PLC on the network, and simply specify the network address and node address of the target PLC. It is possible to connect to the target PLC without doing so. However, in a network in the middle of PLC system construction, there may be a problem with the routing table setting itself. At this time, it is necessary to look around each PLC setting, and it takes a very long time to solve the problem. .

  The present invention has been made paying attention to the above-mentioned problems, and the object of the present invention is to monitor the PLC without connecting to a physical cable by connecting to the PLC via the network. To provide a PLC system capable of shortening the time required for investigating the cause of a communication error when a communication error occurs such that communication via a network is not possible in a PLC system that enables program editing and parameter setting. is there.

  Other objects and operational effects of the present invention should be easily understood by those skilled in the art by referring to the following description of the specification.

  The PLC system of the present invention includes a network including a plurality of PLCs and one development support apparatus, and one of the plurality of programmable controllers is positioned as a relay PLC.

  The development support apparatus can be connected online to the relay PLC via a communication line. Furthermore, the development support apparatus can switch any connection target in the online connection state with the relay PLC, thereby enabling any target on the network. It is possible to connect to the PLC. As a communication line for online connection to a relay PLC via a communication line, the development support apparatus and the relay PLC may be directly connected by a communication cable, or may be connected via a network. good.

  According to such a configuration, the communication path to the target PLC is divided into two sections: a section between the development support apparatus and the relay PLC and a section between the relay PLC and the target PLC. If this occurs, it is easy to investigate the cause.

  In the present invention, when the development support device and the target programmable controller are in a connected state, the development support device repeatedly executes a communication test on both the relay programmable controller and the target programmable controller. To do. Here, when the communication test for the relay programmable controller fails, a display indicating that a communication error has occurred between the development support apparatus and the relay programmable controller is displayed. If the communication test for the relay programmable controller succeeds and the communication test for the target programmable controller fails, a communication error occurs between the relay programmable controller and the target programmable controller. Is displayed.

  According to such a configuration, in the operating state, a communication error occurs in either the section between the development support apparatus and the relay programmable controller or the section between the relay programmable controller and the target programmable controller. It is possible to accurately grasp whether or not a problem has occurred and to quickly recover.

  According to the present invention, in a PLC system that enables PLC monitoring, program editing, parameter setting, etc. without requiring switching of connection of a physical communication cable by connecting to a PLC via a network, When a communication abnormality occurs such that communication cannot be performed, the time required to investigate the cause of the communication abnormality can be shortened.

  In the following, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. An example of a network configuration diagram of a PLC system to which the present invention is applied is shown in FIG.

  As shown in the figure, this PLC system includes nine PLCs (PLC1 to PLC9). These PLCs (PLC1 to PLC9) are connected via eight networks (N1 to N8). That is, PLC1 and PLC2 are connected via the network N1. PLC2 and PLC3 are connected via a network N2. PLC3 and PLC4 are connected via a network N3. PLC4 and PLC5 are connected via a network N4. PLC5 and PLC6 are connected via a network N5. PLC6 and PLC7 are connected via a network N6. PLC7 and PLC8 are connected via a network N7. PLC8 and PLC9 are connected via a network N8. A network constituting the PLC system is assigned a network address as information for uniquely identifying each network. Each PLC includes a node address as information uniquely specified in a directly connected network. The PLC on the PLC system can be uniquely specified by the combination of the network address and the node address.

  Then, the PLC 1 directly connected to the personal computer PC via a cable is referred to as a relay PLC, and the connection destination PLC 9 is referred to as a target PLC.

  Next, a configuration diagram of the apparatus of the present invention is shown in FIG. As shown in the figure, a personal computer (PC) functioning as a development support apparatus includes an input device 201, an output device 202, a communication setting management unit 203, a communication setting data storage DB 204, a connection management unit 205, and a communication command conversion unit. 206, a communication command transmission / reception unit 207, a routing table storage DB 208, and a routing table analysis unit 209. Each of these functional elements is realized by software by incorporating a predetermined program into a personal computer. In the figure, PLC1 is a relay PLC.

  The device of the present invention performs (1) narrowing down of factors by section division and (2) narrowing down of factors by routing table analysis, and notifies the user after clarifying the normal range and abnormal range of communication. The user can reduce the time required for investigating the cause by checking the state of the communication path within the narrowed range.

  Therefore, first, narrowing down of factors by section division will be described.

[Communication settings between PC and relay PLC]
The user uses the input device 201 to set communication specifications between the personal computer PC and the relay PLC (PLC1). For example, the content set by the user is converted into a predetermined format by the communication setting management unit 203 and stored in the communication setting data storage DB 204. The user can change the setting of the communication specification later if necessary.

[Connection between PC and relay PLC]
The user uses the input device 201 to perform an online connection operation with the relay PLC (PLC1) set above. In response to this operation, the connection management unit 205 instructs the communication command conversion unit 206 to execute a communication test for the relay PLC (PLC1). The communication command conversion unit 206 reads the communication setting of the relay PLC (PLC1) from the communication setting data (storage DB 204), and executes a communication test. Then, when the test result is “successful”, the personal computer PC and the relay PLC (PLC1) are in the online mode. On the other hand, when the test result is “failure”, the user is notified through the output device 202 that the communication test with the relay PLC (PLC1) has failed.

[Switching connection to target PLC (PLC9)]
When the personal computer PC and the relay PLC (PLC1) are in the online mode, the user can switch the target PLC by inputting a network address and a node address for designating the target PLC from the input device 201. The connection management unit 205 instructs the communication command conversion unit 206 to execute a communication test for the target PLC (PLC 9). When the test result is “successful”, connection to the designated target PLC (PLC9) is performed. When the test result is “failure”, the user is notified through the output device 202 that the communication test with the relay PLC (PLC1) has failed.

[Check communication during connection]
In the device of the present invention, during communication with the target PLC (PLC 9), the connection management unit 205 sends a relay PLC (to the communication command conversion unit 206 periodically) (initial value is 1 second, and this setting can be changed). A command for a communication test is issued to two locations, PLC 1) and target PLC (PLC 9). When the test result is “success”, the processing up to that point is continued. If the test result is “failed” with the relay PLC, the user is notified through the output device 202 that a communication error has occurred between the personal computer (PC) and the relay PLC (PLC1). . Then switch the system to offline mode. If the test result is “failed” with the target PLC (PLC9), the fact that a communication error has occurred between the relay PLC (PLC1) and the target PLC (PLC9) is notified to the user via the output device 202. Notice. In this case, the system remains in the online mode, and the target PLC (PLC 9) can be switched to another PLC.

  Next, narrowing down of factors by routing table analysis will be described. In the online connection operation, when a situation in which communication with the target PLC (PLC9) cannot be performed occurs, there may be an error in the setting of the routing table in the PLC on the communication path from the relay PLC (PLC1) to the target PLC (PLC9). is there. Conventionally, in this case, it is necessary to check all the individual routing tables, and it takes much time to specify the routing table.

  In the device according to the present invention, when the connection of the target PLC (PLC 9) fails, the user can perform a communication test with another specific target PLC, thereby narrowing down an abnormal part by analyzing the routing table. The outline of this function is to identify a section where communication cannot be performed or an abnormal part by performing a communication test while tracing the routing table from the relay PLC (PLC1) to the target PLC (PLC9).

  The routing table will be described with reference to FIGS. That is, when data is transmitted and received between networks, a table in which communication paths from a certain PLC to a (other) network to which a communication partner PLC is connected is registered in advance in each PLC on the network. It is necessary to be. This table is called a “routing table”. The “routing table” is composed of a “relay network table” and a “own network table”.

  Here, the “relay network table” refers to the target network (final network) to which the PLC is not connected and the PLC that is the first relay point of the route to reach the PLC (the PLC that should go first). 4 is a correspondence table between network addresses and node addresses. By tracing the PLC serving as the relay point, it is possible to reach the final network. On the other hand, the “own network table” is connected to the unit number of the communication unit attached to the PLC (which uniquely identifies the unit in the PLC composed of a plurality of units) and the communication unit. It is a correspondence table with the network address of a network. The routing table is created on a personal computer in which dedicated software is installed, and is transferred to and stored in each PLC.

[Read routing table]
The development support apparatus reads a routing table from a PLC (referred to as an intermediate node) on the communication path. The first intermediate node is assumed to be a relay PLC (PLC # 1) which is the starting point of the communication path. The routing table analysis unit 209 instructs the communication command conversion unit 206 to read the routing table, and stores the read routing table in the routing table storage DB 208. At this time, when the routing table does not exist, the user is notified through the output device 202 that the routing table does not exist in the relay PLC (PLC # 1), and the process is terminated. On the other hand, when a routing table exists, route extraction processing is performed.

[Route Extraction]
The network address and node address of the next intermediate node are extracted from the read routing table. Specifically, the development support apparatus searches for the network address of the target PLC in the order of its own network table and relay network table. At this time, when the network address does not exist, the user is notified through the output device 202 that the network address of the target PLC does not exist in the routing table of the current intermediate node, and the process is terminated. Also, when it exists in its own network table, the network address and node address of the current intermediate node are displayed, and it is highly possible that the communication test has been successful and that there is a problem between the target PLC and the current intermediate node. This is notified to the user through the output device 202 and the process is terminated. On the other hand, when it exists in the relay network table, the network address and node address of the relay point are set to a new intermediate node, and the process proceeds to the routing table reading process.

  Flowcharts (No. 1 and No. 2) showing processing for detecting the above-described abnormal node are shown in FIGS. 5 and 6.

  When the process is started in the figure, in step 501, a process of reading a routing table stored in a predetermined memory of the relay PLC is performed. Specifically, the MPU on the personal computer issues a command for reading a routing table (consisting of a local network table and a relay network table) to the relay PLC. A response from the relay PLC to this command is received. Data relating to the own network table and data relating to the relay network table are extracted from the received response and stored in a predetermined memory as the own network table and the relay network table of the relay PLC.

  In subsequent step 502, the MPU of the personal computer checks whether or not a network number representing the network address of the target PLC exists in its own network table of the relay PLC stored in the predetermined memory in step 501. As a result of the check, if the network number of the target PLC exists, the process proceeds to step 503. As a result of the check, if the network number of the target PLC does not exist, the process proceeds to step 504.

  In step 503, the MPU of the personal computer notifies the operator by displaying the processing result on a display unit (corresponding to the output device 202) of the personal computer. In this case, the communication line to the relay PLC is normal, but the target PLC that is present in the network to which the relay PLC is connected (estimated) (the communication unit or other components constituting the PLC) Display section indicating that communication between the relay PLC and the target PLC is not possible due to a network failure between the relay PLC and the target PLC (such as disconnection of communication line or influence of noise) To display.

  An example of the display is screen example 1 in FIG. In screen example 1, the name of the relay PLC, the network number of the relay PLC, the node number of the relay PLC, and “OK” indicating that the relay PLC is normal are displayed on a predetermined line of the display unit of the personal computer. Is. Further, the name of the target PLC, the network number of the target PLC, the node number of the target PLC, and “NG” indicating that communication with the target PLC is not possible are displayed on lines different from these displays. In addition to these displays, the cause of “NG” may be displayed so that the operator is notified of the cause of the inability to communicate with the target PLC.

  In subsequent step 504, the MPU of the personal computer checks whether the network number of the target PLC exists in the relay network table stored in the predetermined memory in step 501. As a result of the check, if the network number of the target PLC does not exist, the process proceeds to step 505. As a result of the check, if the network number of the target PLC exists, the process proceeds to step 506.

  In step 505, the MPU of the personal computer notifies the operator by displaying the processing result on the display unit of the personal computer. In this case, the communication line up to the relay PLC is normal, but the content that the routing table read from the relay PLC is invalid is displayed on the display unit.

  An example of the display is screen example 2 in FIG. Screen example 2 is “NG” indicating that the name of the relay PLC, the network number of the relay PLC, the node number of the relay PLC, and the routing table of the relay PLC are invalid in a predetermined line of the display unit of the personal computer. Is displayed. In addition to these displays, the cause of “NG” may be displayed so that the operator is notified of the cause of the inability to communicate with the target PLC.

  In subsequent step 506, the MPU of the personal computer notifies the operator by displaying the processing result on the display unit of the personal computer. In this case, the content indicating that the communication line to the relay PLC is normal and the routing table read from the relay PLC is normal is displayed on the display unit.

  An example of the display is screen example 3 in FIG. Screen example 3 is “OK” indicating that the name of the relay PLC, the network number of the relay PLC, the node number of the relay PLC, and the routing table of the relay PLC are normal on a predetermined line of the display unit of the personal computer. Is displayed. After the processing result is displayed on the display unit of the personal computer, the process proceeds to step 601 in FIG.

  Moving to FIG. 6, in the subsequent step 601, the MPU of the personal computer determines a node (referred to as an intermediate node) from which a routing table is to be read next, and performs a process of reading the routing table of the intermediate node. Specifically, a line that matches the network number of the target PLC is extracted from the network address field of the final network in the currently read relay network table, and the network number indicating the network address of the relay network in the line and the relay node A command for reading the routing table is issued to the node (intermediate node) specified by the node number representing the node address. A response from the intermediate node to this command is received. Data relating to the own network table and data relating to the relay network table are extracted from the received response and stored in a predetermined memory as the own network table and the relay network table of the intermediate node.

  In the subsequent step 602, the MPU of the personal computer checks whether the network number of the target PLC exists in the own network table of the intermediate node stored in the predetermined memory in step 601. As a result of the check, if the network number of the target PLC exists, the process proceeds to step 603. As a result of the check, if the network number of the target PLC does not exist, the process proceeds to step 604.

  In subsequent step 603, the MPU of the personal computer notifies the operator by displaying the processing result on the display unit of the personal computer. In this case, the communication circuit up to the intermediate node is normal, but a failure of the target PLC existing in the network to which the intermediate node is connected (estimated) (the communication unit or other units constituting the PLC) Failure) or a failure in the network between the intermediate node and the target PLC (such as a disconnection of the communication line or the influence of noise) is displayed on the display unit to indicate that communication is not possible between the intermediate node and the target PLC.

  An example of the display is screen example 4 in FIG. In screen example 4, the name of the intermediate node, the network number of the intermediate node, the node number of the intermediate node, and “OK” indicating that the intermediate node is normal are displayed on a predetermined line of the display unit of the personal computer. Further, the name of the target PLC, the network number of the target PLC, the node number of the target PLC, and “NG” indicating that communication with the target PLC is not possible are displayed on lines different from these displays. In addition to these displays, the cause of “NG” may be displayed so that the operator is notified of the cause of the inability to communicate with the target PLC.

  In the subsequent step 604, the MPU of the personal computer checks whether the network number of the target PLC exists in the relay network table of the intermediate node stored in the predetermined memory in step 601. As a result of the check, if the network number of the target PLC does not exist, the process proceeds to step 605. As a result of the check, if the network number of the target PLC exists, the process proceeds to step 606.

  In the subsequent step 605, the MPU of the personal computer notifies the operator by displaying the processing result on the display unit of the personal computer. In this case, the communication circuit up to the intermediate node is normal, but the content that the routing table read from the intermediate node is invalid is displayed on the display unit.

  An example of the display is screen example 5 in FIG. Screen example 5 shows the name of the intermediate node, the network number of the intermediate node, the node number of the intermediate node, and “NG” indicating that the routing table of the intermediate node is invalid on the display line of the display unit of the personal computer It is. Further, in addition to these displays, the cause of “NG” may be displayed so that the operator is notified of the cause of the inability to communicate with the target PLC.

  In subsequent step 606, the MPU of the personal computer notifies the operator by displaying the processing result on the display unit of the personal computer. In this case, the communication line to the intermediate node is normal, and the content that the routing table read from the intermediate node is normal is displayed on the display unit.

  The display example is a screen example 6 in FIG. Screen example 6 displays the name of the intermediate node, the network number of the intermediate node, the node number of the intermediate node, and “OK” indicating that the routing table of the intermediate node is normal on a predetermined line of the display unit of the personal computer It is. After the processing result is displayed on the display unit of the personal computer, the process returns to step 601, and thereafter steps 601 to 606 are repeatedly executed.

  In the embodiment described above, it has been described that the process of displaying the process result on the display unit is executed each time. The timing for displaying the processing result on the display unit may be at the end of the flow for detecting an abnormal node. For example, all processing results are stored in a predetermined memory in the middle of a flow for detecting an abnormal node, and the processing results stored when the flow for detecting an abnormal node is terminated are displayed together. Also good.

  In Step 601 of the above-described embodiment, when an intermediate node from which the routing table is to be read is determined, a command for reading the routing table is issued to the intermediate node. The process of reading the routing table is not limited to this. Before issuing a command to read the routing table, issue a command to read information (model, etc.) about the model of the node to the intermediate node, and check whether it is possible to communicate with the corresponding intermediate node based on the response of the command. You may make it determine. When there is a response (when communication is possible), it may be determined whether to read the routing table based on the model information in the response, the reading method in the case of reading, and the like.

  FIG. 13 shows an explanatory diagram collectively showing the relationship between the connection stage and the abnormality notification described above. As is apparent from the figure, in the present invention, first, communication setting between the personal computer and the relay PLC is performed as a first step (step 1301), and then, as a second step, the relay PLC is set. (Step 1302), and as a subsequent third step, connection to the target PLC is switched (step 1303), and then a communication check during connection is performed as a fourth step (step 1305).

  In the second step, if a communication abnormality occurs when connecting to the relay PLC (step 1302), this is notified as a communication abnormality between the personal computer and the relay PLC ( Step 1311).

  In the third step, when a communication abnormality is determined when the connection to the target PLC is switched (step 1303), a routing table analysis process is executed (step 1304). At this time, the fact that the routing table is abnormal (step 1312) and the display of the communicable range (step 1313) are performed.

  Further, in the fourth step, as a result of checking the communication during connection (step 1305), if a communication abnormality is determined, a communication abnormality between the personal computer and the relay PLC (step 1314), and the relay Notification of communication abnormality (step 1315) between the PLC and the target PLC is performed.

  Therefore, the operator can quickly take necessary measures at the time of each abnormality based on those notifications. As a result, the time required for investigating the cause of the communication abnormality can be reduced and the recovery can be performed quickly. It becomes.

  According to the present invention, communication is made via a network in a PLC system that enables PLC monitoring, program editing, parameter setting, etc. without requiring a physical cable connection switching by connecting to the PLC via a network. When a communication abnormality such as inability to occur occurs, it is possible to provide a PLC system capable of reducing the time required to investigate the cause of the communication abnormality.

1 is a network configuration diagram to which the present invention is applied. FIG. It is a block diagram of this invention apparatus. It is a network system diagram. It is explanatory drawing which shows an example of the use routing table from PLC # 1 to PLC # 4. It is a flowchart (the 1) which shows the process for detecting an abnormal node. It is a flowchart (the 2) which shows the process for detecting an abnormal node. It is explanatory drawing of the example 1 of a screen. It is explanatory drawing of the example 2 of a screen. It is explanatory drawing of the example 3 of a screen. It is explanatory drawing of the example 4 of a screen. It is explanatory drawing of the example 5 of a screen. It is explanatory drawing of the example 6 of a screen. It is explanatory drawing which shows the relationship between a connection stage and abnormality notification collectively.

Explanation of symbols

201 Input Device 202 Output Device 203 Communication Setting Management Unit 204 Communication Setting Data Storage DB
205 Connection Management Unit 206 Communication Command Conversion Unit 207 Communication Command Transmission / Reception Unit 208 Routing Table Storage DB
209 Routing table analysis unit PC PC PLC1 Relay PLC
PLC2 to PLC8 PLC in the middle of the network
PLC9 Target PLC

Claims (1)

Including a network including a plurality of programmable controllers and one development support device,
One of the multiple programmable controllers is positioned as a relay programmable controller, and the development support device can be connected online via a communication line to the relay programmable controller. In the online connection state with the relay programmable controller, the device can be connected to any target programmable controller on the network by switching the connection destination.
When the development support device and the target programmable controller are in a connected state, the development support device repeatedly executes a communication test on both the relay programmable controller and the target programmable controller.
When the communication test for the relay programmable controller is failed, a display indicating that a communication error has occurred between the development support device and the relay programmable controller is made.
If the communication test for the relay programmable controller succeeds and the communication test for the target programmable controller fails, a communication error occurs between the relay programmable controller and the target programmable controller. Is displayed,
A programmable controller system characterized by this.

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