JP2008097274A - Communications system for apparatus control - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow reconnection of restored slave stations to communication using a simple instruction operation regardless of the number of the restored slave stations, when one or two or more slave stations disconnected from the communication due to a certain cause are restored and go into communication available, and to realize this kind of reconnection functions at low cost. <P>SOLUTION: When a communication target slave station list stored in a first storage means is collated with respective slave station communication states stored in a second storage means, in response to a predetermined reconnection instruction, slave stations which are determined as being in "communication stopped" condition, even though they are communication targets, are specified, and to each of the specified slave stations, communication is restarted via predetermined procedures. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to device control communication in which one master station and a plurality of slave stations are connected via a field bus, and data is transmitted and received between the master station and each slave station. About the system.

  A communication system for device control in which one master station and a plurality of slave stations are connected via a field bus and data is transmitted / received between the master station and each slave station is conventionally known. (For example, refer to Patent Document 1).

  FIG. 10 shows a basic configuration diagram of such a device control communication system. As shown in the figure, this communication system includes one master station 1 and a plurality of slave stations 2-1 to 2-5 (# 1 to # 5 are numbers for specifying slave stations. ) And the like are connected via the field bus 3, and data is transmitted and received between the master station 1 and each of the slave stations 2-1 to 2-5.

  Note that the master station 1 incorporates processing for device control in itself, and handles both device control and communication, and processing for device control is incorporated in another host device. And the case where only communication processing is mainly performed is included. Similarly, the slave station 2 incorporates processing for device control in itself and takes charge of both device control and communication, and another device for processing for device control. And the case where it mainly handles only communication processing is included.

  The internal memory of the master station 1 is provided with a first area and a second area. In the first area, a communication target slave station list 14a indicating which slave station is currently set as a communication target slave station is stored, and in the second area, each slave station is currently “in communication”, A slave station communication state list 14b indicating which state is “communication stopped” is stored.

  In starting the communication system, the master station 1 executes a predetermined start-up process. That is, in this start-up process, the master station 1 performs a predetermined process on each of the registered slave stations 2-1 to 2-5 in accordance with the communication target slave station list 14a stored in advance. The communication is started through the procedure, and at the same time, the content of the corresponding slave station in the slave station communication state list 14b stored in the master station 1 is rewritten as “in communication”.

  After the communication system is activated, the master station 1 executes a normal process determined in advance. In this normal processing, the master station 1 issues a communication frame (command) including information (such as a slave station ID number) specifying the slave stations 2-1 to 2-5 to the slave station. At this time, when there are a plurality of communication target slave stations, communication frames are sequentially issued to all of the slave stations. On the other hand, on the side of the slave stations 2-1 to 2-5, the communication frames (commands) sent from the master station 1 are selected and acquired for the own station. Each slave station returns a response including information identifying its own station to the master station 1, and the master station 1 acquires a response from each slave station to be communicated based on the information identifying the station.

  After the communication system is activated, the master station monitors the status (normal or abnormal) of each slave station in communication. That is, the master station 1 has returned a response from each slave station in response to transmission to each slave station (received data including information specifying each slave station has been acquired). To monitor. As long as a response is returned from the slave station to be communicated, the slave station is recognized as normal. At this time, the content of the corresponding slave station in the slave station communication state list 14b is maintained as “in communication”.

  On the other hand, if the response from this slave station is interrupted (for example, for a certain period) due to power interruption or failure of the slave station, the master station 1 is in a state where the slave station is disconnected from communication. It recognizes that there is, and shifts to the prescribed processing (for example, processing at the time of abnormality, etc.), and at the same time, the content of the corresponding slave station in the slave station communication state list 14b stored in the master station 1 Rewrite from “Medium” to “Communication Stop”.

  As described above, in the normal processing, the master station 1 transmits a command to each of the slave stations set as communication targets by referring to the communication target slave station list 14a stored in the internal memory. If the response is interrupted during this time, the content of the corresponding slave station in the slave station communication status list 14b stored in the internal memory is changed from “communication” to “communication stop”. And rewrite.

When newly joining a slave station, for example, by using a predetermined tool, adding the target slave station as a target slave station list to the communication target slave station list, and restarting the activation process of the entire communication system It becomes.
JP-A-6-124104

  By the way, several methods have been known for re-subscribing a slave station that has been disconnected from communication due to power interruption, failure, etc., all of which have merits and demerits and sufficient satisfaction has been obtained. There is no current situation.

  FIG. 11 is an explanatory diagram showing the slave station return operation in the first conventional example. In the first conventional example, there is no special mechanism for re-subscribing the slave station that has been disconnected from the communication. Therefore, in order to re-subscribe the slave station that has been disconnected from the communication, it is necessary to restart the entire communication system.

  According to the first conventional example, since there is no dedicated mechanism for re-subscribing the slave station that has been removed from the communication to the communication, the development cost can be reduced by that amount. In order to re-subscribe the slave station to the communication, it is necessary to restart the entire communication system. Therefore, all the slave stations that are in communication must be temporarily stopped, which has a large effect on the entire system and is unusable. There's a problem.

  FIG. 12 is an explanatory diagram showing the slave station return operation in the second conventional example. In the second conventional example, a dedicated mechanism is prepared for re-subscribing the slave station that has been disconnected from the communication. That is, in the second conventional example, a predetermined command transmission is periodically attempted for the slave station that is disconnected from the communication, and the presence or absence of a response from the slave station is monitored. If a state in which a response is returned again is detected by periodic monitoring of the leaving slave station, the slave station is automatically rejoined in communication.

  According to the second conventional example, a slave station that has been disconnected from communication is automatically re-subscribed in communication if it becomes ready for communication upon power-on or failure recovery. Although it is easy to use, it is necessary to monitor the presence of a response from the slave station while periodically trying to send a predetermined command to the slave station that has left communication. There is a problem that the processing load on the master station side is large and the development cost is also high.

  FIG. 13 is an explanatory diagram showing the slave station return operation in the third conventional example. Even in the third conventional example, a dedicated mechanism is provided to re-subscribe a slave station that has been disconnected from the communication. That is, in this third conventional example, means (slave station # 1 to #n communication subscription means) that enable re-subscription or withdrawal of communication are prepared for each of the slave stations. By selecting one of the means from the outside, it is possible to individually resume communication of a slave station in an arbitrary disconnected state.

  According to the third conventional example, it is convenient in that communication of a slave station in an arbitrary disconnection state can be individually resumed, but communication rejoining or disconnection for each slave station is possible. If the number of slave stations increases to 8, 64, etc., it will be necessary to develop a means to enable communication (slave station # 1 to #n communication subscription means). There is a problem that the cost increases.

  The present invention has been made paying attention to the above-mentioned conventional problems, and the object of the present invention is to restore a state in which one or more slave stations that have disconnected from communication for some reason are restored and can communicate. In such a case, regardless of the number of slave stations that have been restored, it is possible to re-subscribe those slave stations to communication with a simple command operation, and to realize such a re-subscription function at a low cost. An object is to provide a communication system for device control.

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

  The above-described problems can be solved by a device control communication system having the following configuration.

  This communication system for device control is configured to connect one master station and a plurality of slave stations via a field bus, and transmit / receive data between the master station and each slave station. Has been.

  The master station includes a first storage means for storing a list of communication target slave stations indicating which slave station is currently set as a communication target slave station, and each of the slave stations is currently “in communication” and “communication stopped” A child set as a communication target by referring to a second storage means for storing a slave station communication state list indicating in which state and a communication target slave station list stored in the first storage means While the command transmission and the reception of the response are repeatedly performed for each of the stations, when the response is interrupted during that time, the command transmission to the slave station is stopped thereafter, and the second storage means Normal time processing means for rewriting the content of the corresponding slave station in the stored slave station communication status list from “in communication” to “communication stop”.

  On the other hand, each of the slave stations receives and decodes the command addressed to the own station from the commands sent from the master station and executes the instructed process, and sends the corresponding response to the master station. Command processing means for transmitting is included.

  Further, in response to a predetermined re-subscription command being given to the master station, a communication target slave station list stored in the first storage means and a slave station communication state list stored in the second storage means To identify the slave stations that have been subject to communication but are in a “communication stop” state, and communicate with each of the identified slave stations through a predetermined procedure. And a re-joining processing means for resuming and rewriting the contents of the corresponding slave station in the slave station communication status list stored in the second storage means from “communication stop” to “communication” Yes.

  According to such a configuration, the communication target slave station list stored in the first storage means indicates which slave station is currently set as the communication target slave station, and is stored in the second storage means. If any of the slave stations is disconnected, the slave station communication status list is automatically rewritten from “during communication” to “communication stop” corresponding to the slave station.

  Accordingly, when a predetermined re-join command is given to the master station when one or more slave stations that have disconnected from communication for some reason are restored and ready to communicate, the first storage means The communication target slave station list stored in the second storage means and the slave station communication state list stored in the second storage means are collated to determine whether the communication target is in the “communication stopped” state. Stations are automatically identified, and communication is resumed for each of the identified slave stations through a predetermined procedure.

  As a result, regardless of the number of restored slave stations, all of the restored slave stations can be re-joined to communication in one command operation, thereby improving the user-friendliness.

  In the above communication system, the master station is a building block PLC communication master station unit, and each slave station is also a various slave station unit such as a remote I / O unit or a remote special function unit. Good.

  According to such a configuration, when one or two or more slave station units that have disconnected from communication for some reason are restored and ready to communicate, a predetermined rejoin command is issued to the communication master station unit. When given, the communication target slave station list stored in the first storage means and the slave station communication state list stored in the second storage means are collated, but the communication target list is “ The slave station units in the “communication stopped” state are automatically identified, and communication is resumed for each of the identified slave station units through a predetermined procedure. As a result, regardless of the number of restored slave stations, all of the restored slave station units can be re-joined in communication by a single command operation, so that the convenience for the user is improved.

  In the above communication system, the master station is set as one of the units constituting the building block type PLC, and the rejoin command is stored in the CPU unit in advance by the CPU unit constituting the building block type PLC. The user program may be given to the master station by executing it.

  According to such a configuration, it is possible to set various conditions for giving a rejoin command via the user program. If this is used, for example, when a predetermined push button switch is operated, when it is determined that a certain condition is satisfied through various sensors, etc., the master station which is one of the units constituting the PLC Can be given a re-join command.

  When the present invention is applied to a building block type programmable controller (hereinafter referred to as “PLC”) as a controller of an apparatus for performing multi-axis control, the master station has a motion control unit having a function for multi-axis control. The slave station can be configured as a motor driver. The motion control unit and the motor driver are connected via a fieldbus. The motor driver drives a motor installed for each target axis of multi-axis control, and is installed for each motor. The motion control unit performs multi-axis control by issuing commands to a plurality of motor drivers via a field bus and controlling the operation of the motor. At this time, under a situation such as maintenance or repair of the device, it is usual that a plurality of motor drivers as slave stations are all turned off and in a communication disconnected state.

  In such a state, the maintenance and repair of the device are completed, and the power is turned on to each motor driver. In this state, the CPU unit, which is the host device, performs a predetermined restart on the motion control unit. When a join command is given, a series of motor drivers that have been in a disconnected state until now are re-joined at the same time, so that the motor driver that is used to control the device becomes ready to operate at the same time. It is.

  Further, in this device control communication system, communication re-subscription for a slave station that has been disconnected is performed after waiting for a re-subscription command to the parent station, and not automatically re-subscription. Therefore, there is no need to monitor the status of the slave station that is leaving. Therefore, in this communication system, unlike the above-described second conventional example, the processing load does not increase due to the monitoring of the slave station that is leaving.

  Furthermore, in this communication unit for device control, the designation of the slave station to be re-joined while resuming communication of a plurality of slave stations at the same time is performed by the communication target stored in the first storage means. Since it is automatically performed by collating the slave station list with the slave station communication state list stored in the second storage means, the communication restart command itself is the same regardless of the number of slave stations to be rejoined. One is sufficient, and unlike the third conventional example, the development cost does not increase according to the number of slave stations.

  According to the present invention, when one or two or more slave stations that have lost communication due to some reason are restored and become communicable, the slave stations are connected regardless of the number of restored slave stations. It is possible to provide a communication system for device control that can re-subscribe to communication by a simple command operation and can realize such a re-subscription function at low cost.

  Hereinafter, a preferred embodiment of a communication system for device control according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows a functional configuration diagram of a master station and a slave station constituting the system of the present invention. As shown in the figure, this communication system connects one master station 1 and a plurality of slave stations 2-1, 2-2,... 1 and the slave stations 2-1, 2-2,... Transmit and receive data.

  As an example of a specific communication procedure, as shown in FIG. 3, an example in which the master station sequentially performs a command / response with each slave station can be given.

  The master station 1 includes a communication processing arithmetic unit 11 mainly composed of a microprocessor, an interface unit 12 for exchanging information with a host device, and each slave station via the field bus 3. A communication interface 13 for exchanging information between them and a storage device 14 are included. The storage device 14 has a first storage area and a second storage area. The first storage area stores a communication target slave station list 14a indicating which slave station is currently set as a communication target slave station. The second storage area stores a slave station communication status list indicating whether each slave station is currently in a “communication”, “not-communication with communication”, or “communication stopped” state. The master station 1 shown in the figure is configured to receive a command from a higher-level device with a built-in device control function and mainly perform a communication function with the slave station 2. Here, the “communication not subscribed” state represents a state of a slave station that is not a communication target slave station. Note that the state of the slave station may be set to two states of “communication” and “communication stop” by including the “communication not subscribed” state in the “communication stop” state.

  On the other hand, on each slave station 2-1, 2-2,..., A slave station side processing / calculation unit 21 mainly composed of a microprocessor and a slave station such as an ID number unique to the slave station A slave station identification setting means 22 for setting identification information and a communication interface 23 for exchanging information with the master station 1 via the field bus 3 are included. The illustrated slave stations 2-1, 2-2,... Are configured to have a device control function in addition to a communication function with the master station 1.

  That is, each slave station 2-1, 2-2,... Fulfills the device control function assigned to its own station, and these slave stations are simultaneously supervised by a host device via the master station. It is controlled.

  When the communication system is activated, the master station 1 executes a predetermined activation process. That is, in this start-up process, the master station 1 follows each of the registered slave stations 2-1, 2-2,... According to the communication target slave station list 14a stored therein in advance. On the other hand, communication is started through a predetermined procedure, and at the same time, the content of the corresponding slave station in the slave station communication state list 14b stored in the master station 1 is rewritten to “in communication”.

  After the communication system is activated, the master station 1 executes a normal process determined in advance. In this normal processing, the master station 1 sends a communication frame (command) including information (slave station ID number, etc.) specifying the slave stations 2-1, 2-2,. Issue. At this time, when there are a plurality of communication target slave stations, communication frames are sequentially issued to all of the slave stations. On the other hand, on the side of the slave stations 2-1 to 2-5, the communication frames (commands) sent from the master station 1 are selected and acquired for the own station. Each slave station returns a response including information identifying its own station to the master station 1, and the master station 1 acquires a response from each slave station to be communicated based on the information identifying the station.

  After the communication system is activated, the master station monitors the status (normal or abnormal) of each slave station in communication. That is, the master station 1 has returned a response from each slave station in response to transmission to each slave station (received data including information specifying each slave station has been acquired). To monitor. As long as a response is returned from the slave station to be communicated, the slave station is recognized as normal. At this time, the content of the corresponding slave station in the slave station communication state list 14b is maintained as “in communication”.

  On the other hand, if the response from this slave station is interrupted (for example, for a certain period) due to power interruption or failure of the slave station, the master station 1 is in a state where the slave station is disconnected from communication. Recognizing that there is a transition to the specified processing (for example, processing at the time of abnormality, etc.), and thereafter, the transmission processing for the slave station is interrupted, and the slave station communication status list stored in the master station 1 The content of the corresponding slave station of 14b is rewritten from “during communication” to “communication stop”.

  As described above, in the normal processing, the master station 1 transmits a command to each of the slave stations set as communication targets by referring to the communication target slave station list 14a stored in the internal memory. If the response is interrupted during this time, the content of the corresponding slave station in the slave station communication status list 14b stored in the internal memory is changed from “communication” to “communication stop”. And rewrite.

  When newly joining a slave station, for example, by using a predetermined tool, adding the target slave station as a target slave station list to the communication target slave station list, and restarting the activation process of the entire communication system It becomes.

  Next, processing when returning to the slave station, which is the main part of the present invention, will be described. FIG. 2 is an explanatory diagram showing a slave station return operation (slave station re-join operation) in the present invention.

  As shown in the figure, the master station 1 is stored in the first storage area (first storage means) of the storage device 14 in response to a predetermined re-join command from the host device. Although the communication target slave station list 14a is collated with the slave station communication state list 14b stored in the second storage area (second storage means), the communication target list is set to the “communication stopped” state. The specified slave station (# 5) is identified, and communication is resumed for each of the identified slave stations (# 5) through a predetermined procedure, and is also stored in the second storage area. Re-submission processing means for rewriting the content (# 5) of the corresponding slave station in the slave station communication status list 14b from “communication stop” to “communication in progress” is included.

  FIG. 4 shows a flowchart showing processing on the master station side including processing for realizing such a re-joining processing means. First, the entire process will be schematically described. The master station 1 waits for a command issue request from a higher-level device (step 408), and when no command issue request arrives (NO in step 408), it does not operate. While generating a command (No Operation command) (step 410), when a command issue request arrives (step 408 YES), command analysis / command generation processing (step 409) is executed.

  The command generated in this manner waits for the command issue timing to arrive (step 403 YES), and is transmitted to the corresponding slave station (step 404). When a response from the slave station has arrived (step 401 YES), the response is acquired (step 402), and thereafter, a process related to the acquired response (step 405) is executed.

  In the above processing flow, when it is determined that there is a communication abnormality due to the absence of a response for a predetermined time or longer (YES in step 406), the specified abnormality processing related to the corresponding slave station is executed and the communication is performed. The leaving process is executed (step 407), and the contents of the slave station communication state list relating to the slave station are rewritten from “during communication” to “communication stop”, and thereafter the transmission process for the slave station is interrupted.

  On the other hand, a flowchart showing processing on the slave station side is shown in FIG. The slave station 2 waits for a command to arrive from the master station 1 (step 601 NO), and acquires the command (step 602). Next, it is determined whether or not the command acquired in step 602 can be processed, that is, whether or not there is a command currently being processed (step 603). If there is no command being processed (NO in step 603), that is, if the command acquired in step 602 can be processed, the process proceeds to step 607 and the acquired command is analyzed. If the command can be executed (YES in step 608), the command is processed (step 604), waits for the process to complete (YES in step 605), generates a completion response (step 606), and generates the generated response. Is transmitted to the master station (step 610). On the other hand, if the analyzed command cannot be executed (NO in step 608) or the command execution has not been completed (NO in step 605), a response in process is generated (step 609), and the generated response is transmitted to the master station. (Step 610).

  Next, returning to FIG. 4, the processing for realizing the re-joining processing means that is the main part of the present invention will be described. In the command analysis / command generation process (step 409), when it is determined that a rejoin request has arrived from the host apparatus (YES in step 4091), a communication rejoin command generation process (step 4092) relating to the leaving slave station is subsequently executed. The

  FIG. 5 shows a detailed flowchart of the process for generating the communication re-subscription command for the communication of the leaving slave station. As shown in the figure, in this communication re-submission command generation process, first, the identification number (ID) of the slave station that is the communication target is acquired from the head of the communication target slave station list (14a in FIG. 2). (Step 501), the communication status of the slave station corresponding to the acquired ID is acquired from the slave station communication status list (14b in FIG. 2) (Step 502). When the acquired communication state is “communication stop” (step 503 YES), a communication re-join command for the corresponding slave station is generated and stored in a predetermined memory (step 504). Next, it is confirmed whether or not there are other slave stations to be communicated in the communication subject slave station list (step 505). If there is another slave station that is the communication target (YES in step 505), the ID of the slave station that is the next communication target in the communication target slave station list is acquired (step 506), and the process returns to step 502. In step 503, if the acquired communication state is not “communication stop”, the process proceeds to step 505. As a result, a communication re-join command is generated for all the slave stations that are communication targets but are “communication stopped”. Then, the communication re-subscription command generated in this way returns to FIG. 4 and waits for the command issuance timing to arrive (step 403 YES), and is transmitted to the corresponding slave station (step 404).

  FIG. 7 shows a flowchart showing the processing on the master station side in the second conventional example. As is clear from the comparison between FIG. 4 and FIG. 7, in the case of the second conventional example, the processing of the portion surrounded by the wavy line in order to automatically rejoin the detached slave station (steps 701 to 704) Thus, each time a predetermined re-subscription confirmation timing arrives (YES in step 701), a response check process (step 702) of the leaving child station is executed and a response is detected. In this case (YES in step 703), the re-submission processing (step 704) of the leaving slave station must be executed, and the processing load of the microprocessor is larger than that of the present invention, and the development cost is correspondingly increased. It will be understood that it is big.

  Finally, FIG. 8 shows a configuration diagram of a PLC system to which the present invention is applied. This PLC system includes a building block type PLC 5 and a plurality of slave station units 6-1 to 6-N.

  As is well known, the PLC 5 has a CPU unit 51, a communication master station unit 52, and other units 53 (input / output units, etc.) via I / O buses laid on the backplane via connectors. It is comprised by attaching and integrating.

  The communication master station unit 52 and the plurality of slave station units 6-1 to 6-N are daisy chain connected via the field bus 7, and the communication procedure is as shown in FIG. An example is adopted in which the master station sequentially performs command / response with each slave station.

  In the CPU unit 51, a user program expressed as a serial connection of an input contact corresponding to a rejoin trigger and a coil output corresponding to a rejoin bit is incorporated as shown in a ladder diagram in the figure.

  When this user program is executed, if the input contact corresponding to the re-join trigger changes from OFF to ON, the coil output corresponding to the re-join bit also changes from OFF to ON (see [1] in the figure). The coil output corresponding to the rejoin bit is read from the input / output memory by the input / output refresh process of the CPU unit 51 and written in a predetermined area of the shared memory 8. The coil output thus written in the predetermined area of the shared memory 8 is read from the communication master station unit 52 at an appropriate timing. As a result, a re-join request is transmitted from the CPU unit 51 to the communication master station unit 52 (see [2] in the figure).

In the communication master station unit that functions as a master station, a communication target child having a number field corresponding to the ID of each slave station and a registration field for registering whether or not the slave station is a slave station to be communicated for each ID A station list, a slave station communication status list having a number column corresponding to the ID of each slave station and a communication status column storing the communication status of the slave station for each ID are stored. In this example, the case where the communication target slave station list and the slave station communication state list are configured as different lists (tables) is shown. However, the present invention is not limited to this, and the communication target slave station list and the slave station communication state list may be combined as a table.
For example, you may comprise as a table provided with the number column corresponding to ID of each sub_station | mobile_unit, a registration column, and a communication status column.

  In response to the request for re-subscription, the communication master station unit 52 collates the communication target slave station list with the slave station communication status list, but is “communication stopped”. The slave stations that are in the state are identified (see [3] in the figure), and communication is resumed for each of the identified slave stations through a predetermined procedure (see [4] in the figure). Then, the content of the corresponding slave station in the slave station communication status list is rewritten from “NG” indicating “communication stop” to “OK” indicating “during communication”. As a result, all of the slave stations that have been subject to communication at that time but are in a communication stopped state are re-joined together. FIG. 9 shows a time chart showing a sequence example in which the above series of flows is viewed from the ladder program. As shown in the figure, the rejoin trigger is changed from OFF to ON, the rejoin bit is changed from OFF to ON, the master station unit busy flag is changed from OFF to ON, and finally the slave station Communication of unit # 2 will be resumed.

  In this PLC system, for example, in the case of maintenance or the like, all of the series of slave station units are in a state where the power is cut off. In order to start the operation of the apparatus from this state, when a power resumption request is issued from the CPU unit 51 to the communication master station unit 52 after the power of each slave station unit is turned on, a series of slave station units are batched. At the same time, the communication is rejoined. That is, if a re-join request is given, communication of these slave station units is resumed collectively without specifying a plurality of target slave station units. Moreover, since only one bit area is required on the shared memory for starting the plurality of slave station units, a large capacity is secured on the shared memory 8 even when 64 slave station units exist. There is no need to do.

  As is clear from the above description of the embodiment, according to the present invention, which slave station is currently set as the communication target slave station in the “communication target slave station list” stored in the first storage means. In addition, the “each slave station communication state” stored in the second storage means is automatically “communication” to “communication stop” corresponding to the slave station when any slave station is disconnected. Is rewritten.

  Accordingly, when a predetermined re-join command is given to the master station when one or more slave stations that have disconnected from communication for some reason are restored and ready to communicate, the first storage means A child that is in a “communication stop” state although it is a communication target by collating the communication target slave station list stored in FIG. 2 with each slave station communication state stored in the second storage means Stations are automatically identified, and communication is resumed for each of the identified slave stations through a predetermined procedure.

  As a result, regardless of the number of restored slave stations, all of the restored slave stations can be re-joined to communication in one command operation, thereby improving the user-friendliness. Further, when the present invention is applied to a building block type programmable controller (hereinafter referred to as PLC) as a controller of a device for performing multi-axis control, the master station has a motion control having a function for multi-axis control. As a unit, the slave station can be configured as a motor driver. At this time, under a situation such as maintenance or repair of the device, it is usual that a plurality of motor drivers as slave stations are all turned off and in a communication disconnected state.

  In such a state, the maintenance and repair of the device are completed, and the power is turned on to each motor driver. In this state, the CPU unit, which is the host device, performs a predetermined restart on the motion control unit. When a join command is given, a series of motor drivers that have been in a disconnected state up to now will be re-joined at the same time, so all of the motor drivers that are used to control the device will be able to operate simultaneously. Convenient.

  Further, in this device control communication system, communication re-subscription for a slave station that has been disconnected is performed after waiting for a re-subscription command to the parent station, and not automatically re-subscription. Therefore, there is no need to monitor the status of the slave station that is leaving. Therefore, in this communication system, unlike the above-described second conventional example, the processing load does not increase due to the monitoring of the slave station that is leaving.

  Furthermore, in this communication unit for device control, the designation of the slave station to be re-joined while resuming communication of a plurality of slave stations at the same time is performed by the communication target stored in the first storage means. Since it is automatically performed by collating the slave station list with each slave station communication state stored in the second storage means, the communication restart command itself is the same regardless of the number of slave stations to be rejoined in communication. One is sufficient, and unlike the third conventional example, the development cost does not increase according to the number of slave stations.

  According to the present invention, when one or two or more slave stations that have lost communication due to some reason are restored and become communicable, the slave stations are connected regardless of the number of restored slave stations. It is possible to provide a communication system for device control that can re-subscribe to communication by a simple command operation and can realize such a re-subscription function at low cost.

It is a functional block diagram of the master station and the slave station that constitute the system of the present invention. It is explanatory drawing which shows the subunit | mobile_unit return operation | movement in this invention. It is a schematic explanatory drawing which shows the example which performs a command and a response with each slave station in order. It is a flowchart which shows the process by the side of the master station in this invention. It is a detailed flowchart of the generation process of the communication re-join command of the leaving slave station. It is a flowchart which shows the process by the side of the subunit | mobile_unit in this invention. It is a flowchart which shows the process by the main | base station in the 2nd prior art example. 1 is a configuration diagram of a PLC system to which the present invention is applied. It is a time chart which shows the example of a sequence seen from the ladder program. 1 is a basic configuration diagram of a communication system including a single master station and a plurality of slave stations as a premise of the present invention. It is a flowchart which shows the subunit | mobile_unit return operation | movement in a 1st prior art example. It is a flowchart which shows the subunit | mobile_unit return operation | movement in a 2nd prior art example. It is a flowchart which shows the slave station return operation | movement in a 3rd prior art example.

Explanation of symbols

1 Master station 2-1 to 2-n Slave station 3 Fieldbus 5 Programmable controller (PLC)
6-1 to 6 -N Slave station unit 7 Field bus 8 Shared memory 11 Communication processing operation unit 12 Interface (I / F) with host device
13 Communication interface (I / F)
DESCRIPTION OF SYMBOLS 14 Memory | storage device 14a Communication object slave station list 14b Slave station communication status list 21 Slave station side processing and calculating part 22 Slave station identification setting means 23 Communication interface 51 CPU unit 52 Communication master station unit 53 Other units

Claims (3)

In a communication system for device control in which one master station and a plurality of slave stations are connected via a field bus, and data is transmitted and received between the master station and each slave station.
The master station
First storage means for storing a communication target slave station list indicating which slave station is currently set as a communication target slave station;
A second storage means for storing a slave station communication status list indicating whether each slave station is currently in a “communication” or “communication stop” state;
By referring to the communication target slave station list stored in the first storage means, while repeatedly executing command transmission and response reception for each of the slave stations set as communication targets, When the response is interrupted, thereafter, the command transmission to the slave station is stopped, and the contents of the corresponding slave station in the slave station communication status list stored in the second storage means are changed from “in communication” to “communication”. Normal processing means to rewrite to `` stop '',
Each slave station has
Includes command processing means that receives and decodes commands addressed to its own station from the commands sent from the master station, executes the instructed process, and sends the corresponding response to the master station And the master station
In response to the given re-subscription command being given, by comparing the communication target slave station list stored in the first storage means with the slave station communication status list stored in the second storage means, Identify the slave stations that are subject to communication but are in a “communication stop” state, and resume communication for each of the identified slave stations through a predetermined procedure. Re-subscription processing means for rewriting the content of the corresponding slave station in the slave station communication status list stored in the storage means of 2 from “communication stop” to “communication in progress”;
A communication system for device control.   The master station is a communication master station unit of a building block type PLC, and each of the slave stations is a slave unit such as a remote I / O unit or a remote special function unit. A communication system for device control according to 1.   The master station is one of the units constituting the building block type PLC, and the re-join command executes a user program in which the CPU unit constituting the building block type PLC is stored in the CPU unit in advance. The communication system for device control according to claim 1, wherein the communication is provided to the master station.

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