JP3791563B2 - Data exchange method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a data exchange method and apparatus using cyclic communication (data link).
[0002]
[Prior art]
Conventionally, a configuration shown in FIG. 10 is known as a communication system for exchanging data using cyclic communication (data link). The communication system shown in FIG. 10 reads / writes communication data to / from the user program 11 of the programmable controller 10 via the communication medium 40, the communication controller 30, and the shared memory 20. A buffer 21, an exclusion flag 22, and a completion flag 23 are provided, and the communication controller 30 is provided with a plurality of reception data buffers 31 and transmission data buffers 32.
[0003]
In FIG. 10, the communication controller 30 periodically receives communication data of other stations from the communication medium 40 regardless of the command from the user program 11 of the programmable controller 10 as shown in the time chart of FIG. -A) The received communication data is stored in the reception data buffer 31, and the transmission data stored in the transmission data buffer 32 is transmitted to the communication medium 40 in accordance with the transmission timing of the own station (WB). ).
[0004]
Further, the communication controller 30 copies the reception data stored in the reception data buffer 31 to the communication data buffer 21 of the shared memory 20 (RB) unless there is an instruction from the programmable controller 10, and the shared memory 20 The transmission data stored in the communication data buffer 21 is copied to the transmission data buffer 32 (W-A).
[0005]
When a read command is issued from the user program 11 (R-1), the communication driver 12 of the programmable controller 10 reads the received data copied to the communication data buffer 21 of the shared memory 20 from the communication data buffer 21 in the above procedure. (R-2), this is handed over to the user program 11 (R-3).
[0006]
By the way, while the received data is read from the communication data buffer 21 of the shared memory 20 and delivered to the user program 11 of the programmable controller 10, the received data shared memory 20 stored in the received data buffer 31 of the communication controller 30 is transferred. When the copy to the communication data buffer 21 occurs, the received data handed over to the user program 11 of the programmable controller 10 changes to new received data from the middle. As a result, the consistency of the data is destroyed and the reliability of the data is increased. Is lost.
[0007]
Therefore, in the communication system shown in FIG. 10, an exclusive flag 22 and a completion flag 23 are provided in the shared memory 20 provided between the programmable controller 10 and the communication controller 30, and programmable from the communication data buffer 21 of the shared memory 20. The controller 10 is configured to perform exclusive control of the received data transfer process to the user program 11 and the received data copy process from the received data buffer 31 of the communication controller 30 to the communication data buffer 21 of the shared memory 20. .
[0008]
12 and 13 are flowcharts showing the exclusive control. FIG. 12 shows a communication process of the communication driver 12 of the programmable controller 10, and FIG. 13 shows a communication process of the communication controller 30.
[0009]
That is, in FIG. 12, the communication driver 12 of the programmable controller 10 first turns on the exclusive flag 22 of the shared memory 20 (step 101), and then determines whether the completion flag 23 of the shared memory 20 is on. Check (step 102).
[0010]
If the completion flag 23 of the shared memory 20 is not ON (NO in step 102), the process returns to step 102 and waits until the completion flag 23 is turned ON. If the completion flag 23 of the shared memory 20 is ON ( In step 102, the received data is transferred from the communication data buffer 21 of the shared memory 20 to the user program 11 of the programmable controller 10 (step 103).
[0011]
When the received data transfer process from the communication data buffer 21 of the shared memory 20 to the user program 11 of the programmable controller 10 is completed, the exclusive flag 22 of the shared memory 20 is turned off (step 104), and the completion flag 23 is turned off. (Step 105), the process is terminated.
[0012]
In FIG. 13, the communication controller 30 first checks whether or not the exclusive flag 22 of the shared memory 20 is ON (step 201). Here, if the exclusive flag 22 of the shared memory 20 is not ON (step 201). In step 201, the received data is copied from the received data buffer 31 of the communication controller 30 to the communication data buffer 21 of the shared memory 20 (step 202), and then the communication data buffer 21 of the shared memory 20 communicates. The transmission data is copied to the transmission data buffer 32 of the controller 30 (step 203), and the process returns to step 201.
[0013]
If it is determined in step 201 that the exclusive flag 22 of the shared memory 20 is ON (YES in step 201), it is next checked whether or not the completion flag 23 of the shared memory 20 is OFF (step 201). 204).
[0014]
If the completion flag 23 of the shared memory 20 is not OFF (NO in step 204), the process returns to step 201. If the completion flag 23 of the shared memory 20 is OFF (YES in step 204), then the previous time It is checked whether the interval from the exclusive processing is equal to or longer than one communication cycle time (step 205).
[0015]
If the interval from the previous exclusive process is not longer than one communication cycle time (NO in step 205), the process proceeds to step 202, and reception from the reception data buffer 31 of the communication controller 30 to the communication data buffer 21 of the shared memory 20 is performed. Data copy processing is executed, and subsequently, transmission data copy processing from the communication data buffer 21 of the shared memory 20 to the transmission data buffer 32 of the communication controller 30 is executed (step 203), and the processing returns to step 201.
[0016]
If it is determined in step 205 that the interval from the previous exclusive process is equal to or longer than one communication cycle time (YES in step 205), the completion flag 23 of the shared memory 20 is turned on (step 206). Return to.
[0017]
That is, on the communication controller 30 side, a restriction is provided on the exclusive process on the communication driver 12 side of the programmable controller 10 so that the time interval from the previous exclusive process is 1 communication cycle or more. This is to prevent the time when the communication controller 30 side operates the communication data buffer 21 of the shared memory 20 when the exclusive processing from the communication driver 12 side of the programmable controller 10 is frequently performed.
[0018]
[Problems to be solved by the invention]
However, in a communication system that exchanges data using the conventional cyclic communication (data link),
1) Since exclusive control affects the communication cycle time, the user program is stopped for one communication cycle time.
2) Therefore, the performance of a user program that continuously reads / writes reliable communication data cannot be made faster than the communication cycle time. 3) The communication cycle time is the amount of data transmitted to the communication medium. The performance of the user program varies greatly depending on the usage conditions of the communication medium.
There was a problem.
[0019]
Therefore, the present invention eliminates the influence of the communication cycle time on the performance of the user program that continuously reads / writes reliable communication data, and eliminates the fluctuation of the performance of the user program due to the use condition of the communication medium. It is an object to provide an exchange method and apparatus.
[0020]
[Means for Solving the Problems]
  In order to achieve the above object, according to the first aspect of the present invention, a shared memory for exchanging data is connected between a communication controller connected to a communication medium accommodating a plurality of nodes and a terminal. The received data cyclically received from the communication medium via the communication controller is copied to the shared memory, and the received data copied to the shared memory is read in response to a read command from the terminal to the terminal. A data exchange method using cyclic communication, wherein the communication controller transmits the received data;In the above node unitStoreforA reception data buffer is provided, and reception data cyclically received from the communication medium is stored in the reception data buffer.In the above node unitThe shared memory stores received data for each node.For storingCommunication data bufferAnd a reception flag provided for each node and indicating whether or not the reception data is stored in the communication data buffer in units of nodes.As well asThatThe received data stored in the received data buffer of the communication controller is copied to the communication data buffer for each of the plurality of nodes, and the new received data delivered to the terminalCommunication data bufferStored inThe reception flag indicates storage of received dataOnly if its shared memoryCommunication data bufferIt is possible to deliver received data from the terminal to the terminal.
[0022]
  Claims2The invention of claim 1 is the invention of claim 1,
  The operation of reading the received data copied to the shared memory and delivering it to the terminal is as follows:
  It is performed through a cache memory provided in the terminal.
[0023]
  Claims3The invention of claim 1 is the invention of claim 1,
  The terminal
  It consists of a programmable controller having a user program and a communication driver.
[0024]
  Claims4The invention of claim2In the invention of
  The terminal
It consists of a programmable controller having a user program and a communication driver,
  The cache memory is
  It is provided in the communication driver.
[0025]
  Claims5In the invention, a shared memory for exchanging data between a communication controller connected to a communication medium accommodating a plurality of nodes and a programmable controller is connected, and the communication medium is connected via the communication controller. Use cyclic communication to copy the received data cyclically received from the above to the shared memory, read the received data copied to the shared memory in response to a read command from the programmable controller and deliver it to the programmable controller The communication controller includes a reception data buffer that stores reception data cyclically received from the communication medium in units of nodes, and the shared memory stores the data to be exchanged in units of nodes. Communication data buffer stored in Management means for managing exclusive processing of the exchanged data stored in the communication data buffer in units of nodes, and the management means is provided for each node and the exchanged data is stored in the node A reception flag indicating whether or not the data is stored in the communication data buffer in units is provided.
[0027]
  Claims6The invention of claim5In the invention of
  The programmable controller is
  A user program section for storing a user program;
  A communication driver for communicating with the shared memory;
  It is characterized by comprising.
[0028]
  Claims7According to the invention of claim 6,
  The communication driver
  A cache memory that once reads and stores the received data copied to the shared memory;
  It is characterized by comprising.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0030]
FIG. 1 is a schematic block diagram showing an embodiment of a communication system constructed by applying a data exchange method and apparatus according to the present invention.
[0031]
The communication system shown in FIG. 1 can be configured by adding the following configuration to the shared memory 20 of the conventional communication system shown in FIG.
1) Communication data buffers 21-1 to 21-n in node units
2) Reception flags 22-1 to 22-n in node units
3) Exclusive flags 23-1 to 23-n in node units
4) Start flag 24 indicating the start of exclusive processing
5) Completion 1 flag 25 indicating completion 1
6) Completion 2 flag 26 indicating completion 2
[0032]
Here, the start flag 24 of 4) and the completion 1 flag 25 of 5) and the completion 2 flag 26 of 6) can also be configured from an interrupt notification to the communication driver 12 and the communication controller 30 of the programmable controller 10.
[0033]
As shown in the time chart of FIG. 2, the communication controller 30 periodically receives communication data of other stations (other nodes) from the communication medium 40 regardless of instructions from the user program 11 of the programmable controller 10 (Rx A) The received communication data is stored in the reception data buffer (x) 31, and the transmission data stored in the transmission data buffer 32 is transmitted to the communication medium 40 in accordance with the transmission timing of the own station ( W-B).
[0034]
Further, the communication controller 30 copies the reception data stored in the reception data buffer 31 to the communication data buffers 21-1 to 21-n of the shared memory 20 (Rx-B) unless there is an instruction from the programmable controller 10. Further, the transmission data stored in the communication data buffers 21-1 to 21-n of the shared memory 20 are copied to the transmission data buffer 32 (W-A).
[0035]
When a read command is issued from the user program 11 (R-1), the communication driver 12 of the programmable controller 10 corresponds to the communication data buffer 21 corresponding to the received data copied to the communication data buffer 21 of the shared memory 20 in the above procedure. Read from 1 to 21-n (Rx-2), and hand it over to the user program 11 (R-3).
[0036]
By the way, in the communication system shown in FIG. 1, the communication of the programmable controller 10 is performed only when there is new reception data to be read in the communication data buffers 21-1 to 21-n of the shared memory 20, as shown in FIG. The driver 12 is configured to allow the received data to be read from the communication data buffers 21-1 to 21-n of the shared memory 20.
[0037]
In addition, when there is no new received data to be read in the communication data buffers 21-1 to 21-n of the shared memory 20, the communication driver 12 of the programmable controller 10 sends a read result to the user program of the programmable controller 10. Notify as a failure.
[0038]
FIG. 3 is a flowchart showing reception processing for a specific node by the communication driver 12 of the programmable controller 10 shown in FIG.
[0039]
In FIG. 3, the communication driver 12 of the programmable controller 10 first checks whether or not the reception flag 22-2 (reception flag 2) corresponding to a specific node of the shared memory 20, for example, the node (2) is ON. (Step 301).
[0040]
Here, when the reception flag 22-2 (reception flag 2) is not ON (NO in step 301), there is no new reception data to be read out, and therefore the result of reading out to the user program of the programmable controller 10 is regarded as failure. Notification is made (step 311).
[0041]
If it is determined in step 301 that the reception flag 22-2 (reception flag 2) is ON (YES in step 301), the exclusive corresponding to this reception flag 22-2 (reception flag 2) is then performed. The flag 23-2 (exclusive flag 2) is turned on (step 302), and then the start flag 24 of the shared memory 20 is turned on (step 303).
[0042]
Next, it is checked whether the completion 1 flag 25 of the shared memory 20 is ON (step 304). If the completion 1 flag 25 of the shared memory 20 is not ON (NO in step 304), the process returns to step 304, and the shared memory 20 20 until the completion 1 flag 25 of the shared memory 20 is turned on. When the completion 1 flag 25 of the shared memory 20 is turned on (YES in step 304), the user program 11 of the programmable controller 10 is transferred from the communication data buffer 21-2 of the shared memory 20. The received data is transferred to the server (step 305).
[0043]
When the reception data transfer process from the communication data buffer 21-2 of the shared memory 20 to the user program 11 of the programmable controller 10 is completed, the corresponding reception flag 22-2 of the shared memory 20 is turned OFF (step 306). Next, the corresponding exclusive flag 23-2 is turned off (step 307), then the start flag 24 is turned off (step 308), and then the completion 1 flag 25 is turned off (step 309). Is successful (step 310).
[0044]
FIG. 4 is a flowchart showing a reception process for a specific node by the communication controller 30 shown in FIG.
[0045]
In FIG. 4, the communication controller 30 first checks whether the start flag 24 of the shared memory 20 is ON (step 401).
[0046]
If the start flag 24 of the shared memory 20 is not ON (NO in step 401), the process proceeds to step 404. If the start flag 24 of the shared memory 20 is ON (YES in step 401), then the shared memory 20 It is checked whether the 20 completion 1 flag 25 is OFF (step 402).
[0047]
If the completion 1 flag 25 is not OFF (NO in step 402), the process proceeds to step 404. If the completion 1 flag 25 is OFF (YES in step 402), the completion 1 flag 25 of the shared memory 20 is turned ON. (Step 403), the process proceeds to step 404.
[0048]
In step 404, data for the node (x) corresponding to the node (x) is received from the communication medium 40. When reception of data for the node (x) is completed, it is next checked whether or not the corresponding exclusive flag 23-x (exclusive flag x) of the shared memory 20 is OFF (step 405).
[0049]
If the exclusive flag 23-x (exclusive flag x) is not OFF (NO in step 405), the process returns to step 401.
[0050]
If it is determined in step 405 that the exclusion flag 23-x (exclusion flag x) is OFF (YES in step 405), the communication of the shared memory 20 from the reception data buffer 31 (x) of the communication controller 30 is performed. The received data is copied to the data buffer 21-x (step 406), the corresponding reception flag 22-x of the shared memory 20 is turned on (step 407), and the process returns to step 401.
[0051]
FIG. 5 is a flowchart showing the transmission process of the communication driver 12 when the local node data is transmitted from the user program 11 of the programmable controller 10.
[0052]
In FIG. 5, the communication driver 12 of the programmable controller 10 first checks whether the completion 2 flag 26 of the shared memory 20 is OFF (step 501). If the completion 2 flag 26 of the shared memory 20 is not OFF (NO in step 501), the process returns to step 501, waits until the completion 2 flag 26 of the shared memory 20 is turned OFF, and the completion 2 flag of the shared memory 20 is When 26 is turned off (YES in step 501), the exclusive flag of the own node is turned on (step 502).
[0053]
Next, the start flag 24 is turned on (step 503), and it is checked whether the completion 1 flag 25 of the shared memory 20 is on (step 504).
[0054]
If the completion 1 flag 25 of the shared memory 20 is not ON (NO in step 504), the process returns to step 504 and waits until the completion 1 flag 25 of the shared memory 20 is turned on.
[0055]
When the completion 1 flag 25 of the shared memory 20 is turned ON (YES in step 504), a process of writing the own node data transmitted from the user program 11 of the programmable controller 10 to the communication data buffer of the shared memory 20 is performed (step 505).
[0056]
When the processing in step 505 is completed, the reception flag of the own node of the shared memory 20 is turned on (step 506), the exclusion flag of the own node is then turned off (step 507), and then the completion 2 flag 26 is turned on (step 509), and finally the start flag 24 is turned off (step 510). This processing is successful (step 511).
[0057]
FIG. 6 is a flowchart showing the transmission process of the communication controller 30 when transmitting the own node data from the user program 11 of the programmable controller 10.
[0058]
In FIG. 6, the communication controller 30 first checks whether the start flag 24 of the shared memory 20 is ON (step 601).
[0059]
If the start flag 24 is not ON (NO in step 601), the process proceeds to step 604.
[0060]
If it is determined in step 601 that the start flag 24 is ON (YES in step 601), it is then checked whether the completion 1 flag 25 of the shared memory 20 is OFF (step 602).
[0061]
If the completion 1 flag 25 is not OFF (NO in step 602), the process proceeds to step 604.
[0062]
If the completion 1 flag 25 is OFF in step 602 (YES in step 602), the completion 1 flag 25 is set to ON and the process proceeds to step 604.
[0063]
In step 604, it is checked whether the exclusive flag of the own node is OFF. If the exclusive flag of the own node is not OFF (NO in step 604), the process returns to step 601.
[0064]
If the exclusive flag of the own node is OFF in step 604 (YES in step 604), it is next checked whether the reception flag of the own node is ON (step 605).
[0065]
If the reception flag of the own node is not ON (NO in step 605), the process returns to step 601.
[0066]
In step 605, if the reception flag of the own node is ON (YES in step 605), the transmission data written in the communication data buffer of the own node of the shared memory 20 is copied to the transmission buffer 32 of the communication controller 30. The processing to be executed is executed (step 606).
[0067]
When the processing in step 606 is completed, the reception flag of the own node is turned off (step 607), the completion 2 flag 26 is turned off (step 608), and the process returns to step 601.
[0068]
FIG. 7 is a schematic block diagram showing another embodiment of a communication system configured by applying the data exchange method and apparatus according to the present invention.
[0069]
The communication system shown in FIG. 7 includes a communication data buffer (hereinafter referred to as a cache memory) 13 for all node areas in the communication driver 12 of the programmable controller 10 of the communication system shown in FIG. Can be configured.
[0070]
In the communication system shown in FIG. 7, data on the communication data buffer 21 of the shared memory 20 is once read into the cache memory 13 in the communication driver 12 of the programmable controller 10, and the user program 11 of the programmable controller 10 is The contents stored in the cache memory 13 are notified.
[0071]
In this communication system, when there is no new data to be received on the communication data buffer 21 of the shared memory 20, the previous read content stored in the cache memory 13 is stored in the user program 11 of the programmable controller 10. Notify them.
[0072]
Further, in this communication system, as viewed from the user program 11 of the programmable controller 10, data for a plurality of nodes can be operated at a time. In addition, during this operation, for the data for nodes that are not exclusively controlled, new data from the communication controller 30 can be copied in parallel to the communication data buffer 21 of the shared memory 20.
[0073]
FIG. 8 is a time chart showing exclusive control for a plurality of nodes in the communication system shown in FIG. In addition, in FIG. 8, the operation example in the case of operating node (1), (2) from the user program 11 of the programmable controller 10 is shown. Note that the communication controller 30 and its own node data transmission process are the same as those in the communication system described with reference to FIGS.
[0074]
FIG. 9 is a flowchart showing reception processing for a plurality of nodes by the communication driver 12 of the programmable controller 10 shown in FIG. In addition, in FIG. 9, the operation example in the case of operating node (1), (2) from the user program 11 of the programmable controller 10 is shown like FIG.
[0075]
9, the communication driver 12 of the programmable controller 10 first checks whether or not the reception flag 22-1 (reception flag 1) corresponding to the node (1) of the shared memory 20 is ON (step 901).
[0076]
If the reception flag 22-1 (reception flag 1) is not ON (NO in step 901), the process proceeds to step 903.
[0077]
If the reception flag 22-1 (reception flag 1) is ON in step 901 (YES in step 901), the corresponding exclusive flag 23-1 (exclusive flag 1) is turned ON (step 902), and step 903 is performed. Proceed to
[0078]
In step 903, it is checked whether or not the reception flag 22-2 (reception flag 2) corresponding to the node (2) of the shared memory 20 is ON.
[0079]
If the reception flag 22-2 (reception flag 2) is not ON (NO in step 903), the process proceeds to step 905.
[0080]
If the reception flag 22-2 (reception flag 2) is ON in step 903 (YES in step 903), the corresponding exclusive flag 23-2 (exclusive flag 2) is turned ON (step 904), and step 905 is performed. Proceed to
[0081]
In step 905, the start flag 24 of the shared memory 20 is set to ON, and then it is checked whether the completion 1 flag 25 is ON (step 906). If the completion 1 flag 25 of the shared memory 20 is not ON (step 906). If the completion 1 flag 25 is turned on (YES in step 906), then the exclusive flag 22-1 (exclusive flag 1) is set. Whether it is ON is checked (step 907).
[0082]
If the exclusive flag 22-1 (exclusive flag 1) is not ON (NO in step 907), the process proceeds to step 911.
[0083]
If the exclusive flag 22-1 (exclusive flag 1) is ON in step 907 (YES in step 907), the cache memory 13 of the communication driver 12 of the programmable controller 10 is transferred from the communication data buffer 21-1 of the shared memory 20. Data reading processing is executed (step 908).
[0084]
When the processing in step 908 is completed, the corresponding reception flag 22-1 of the shared memory 20 is turned off (step 910), and the process proceeds to step 911.
[0085]
In step 911, it is checked whether or not the exclusive flag 22-1 (exclusive flag 1) is ON. If the exclusive flag 22-1 (exclusive flag 1) is not ON (NO in step 911), the process proceeds to step 913.
[0086]
If the exclusive flag 22-2 (exclusive flag 2) is ON in step 911 (YES in step 911), the cache memory 13 of the communication driver 12 of the programmable controller 10 is transferred from the communication data buffer 21-2 of the shared memory 20. The data reading process is executed (step 912), and the process proceeds to step 913.
[0087]
In step 913, the corresponding reception flag 22-2 of the shared memory 20 is turned off, and then the corresponding exclusion flag 23-2 is turned off (step 914).
[0088]
And the process which notifies the data read to the cache memory 13 to the user program 11 of the programmable controller 10 is performed (step 915).
[0089]
Thereafter, the start flag 24 of the shared memory 20 is turned off (step 916). Finally, the completion 1 flag 25 is turned off (step 917), and this process ends.
[0090]
【The invention's effect】
As described above, according to the first aspect of the present invention, received data periodically received from a plurality of nodes is copied to a shared memory, and the received data copied to the shared memory is corresponded to a read command from a terminal. In the data exchange method of reading and transferring to the terminal, the shared memory manages the received data in node units, and only when new received data to be transferred to the terminal is stored in the shared memory, Since it is configured to enable delivery, it is possible to eliminate the influence of the communication cycle time when continuously reading / writing reliable communication data, and to eliminate performance fluctuations due to the use conditions of the communication medium. There is an effect.
[0091]
According to a second aspect of the present invention, in the first aspect of the present invention, the shared memory receives a communication data buffer for copying the received data for each node, and receives data for each node with respect to the communication data buffer. A reception flag to be managed, a first operation for copying the reception data to the communication data buffer, and a second operation for reading the reception data from the communication data buffer and delivering it to the terminal in response to a read command from the terminal In addition to the effect of the invention of claim 1, since the exclusive flag for managing the exclusive process with the operation in units of nodes and the start and complete flag for managing the start and completion of the exclusive process are stored. Therefore, the exclusive function can be operated only at necessary portions, and the completion of the exclusive process can be performed in any part of the communication cycle.
[0092]
According to a third aspect of the invention, in the first aspect of the invention, the operation of reading the received data copied to the shared memory and delivering it to the terminal is performed via a cache memory provided in the terminal. Thus, it is possible to manipulate data of a plurality of nodes at a time as viewed from the terminal side. Further, during this operation, data for nodes not exclusively controlled can be copied in parallel.
[0093]
According to a fourth aspect of the invention, in the first aspect of the invention, the terminal comprises a programmable controller having a user program and a communication driver. In the fifth aspect of the invention, the terminal of the fourth aspect is provided. In the above configuration, the cache memory is provided in the communication driver, so that data of a plurality of nodes can be manipulated at a time as viewed from the programmable controller side. Further, during this operation, data for nodes not exclusively controlled can be copied in parallel.
[0094]
In the invention of claim 6, a communication controller connected to a communication medium accommodating a plurality of nodes, a programmable controller, connected between the communication controller and the programmable controller, the communication controller and the programmable controller. And a shared memory for exchanging data with the controller. The shared memory is stored in the data storage means for storing the data to be exchanged in units of nodes and the data storage means. In addition, since the management means for managing the exclusive processing of the exchanged data in units of the nodes is provided, the influence of the communication cycle time when the reliable reading / writing of the communication data is continuously performed. Performance fluctuations due to the use conditions of the communication medium. Camphor it is advantageously possible to provide a data switching apparatus can.
[0095]
According to a seventh aspect of the present invention, in the sixth aspect of the present invention, the data storage means includes a plurality of communication data buffers for copying received data received by the communication controller for each node, and the management The means includes: a reception flag for managing data reception for each node to the communication data buffer; a first operation for copying received data received by the communication controller to the communication data buffer; and a read command from the programmable controller The exclusive flag for managing the exclusive process with the second operation for reading the received data copied to the communication data buffer corresponding to the second operation to the programmable controller for each node, and the start indicating the start and completion of the exclusive process And a completion flag, so that the effect of the invention of claim 6 is achieved. In addition, only required locations can be so exclusive function operates, it is possible to perform any part of the communication cycle the exclusive process is completed.
[0096]
According to an eighth aspect of the present invention, in the sixth aspect of the present invention, the programmable controller includes a user program unit that stores a user program and a communication driver that performs communication between the shared memory. Further, in the invention of claim 9, in the invention of claim 8, the communication driver comprises a cache memory that once reads and stores the received data copied to the shared memory. And According to this configuration, data of a plurality of nodes can be manipulated at a time as viewed from the programmable controller side. Further, during this operation, data for nodes not exclusively controlled can be copied in parallel.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram showing an embodiment of a communication system configured by applying a data exchange method and apparatus according to the present invention.
FIG. 2 is a time chart for explaining the operation of the communication system shown in FIG. 1;
FIG. 3 is a flowchart showing reception processing for a specific node by a communication driver of the programmable controller shown in FIG. 1;
4 is a flowchart showing reception processing for a specific node by the communication controller shown in FIG. 1;
FIG. 5 is a flowchart showing transmission processing of a communication driver in the case of transmitting own node data from the user program of the programmable controller shown in FIG. 1;
6 is a flowchart showing a transmission process of the communication controller when transmitting its own node data from the user program of the programmable controller shown in FIG. 1;
FIG. 7 is a schematic block diagram showing another embodiment of a communication system configured by applying the data exchange method and apparatus according to the present invention.
FIG. 8 is a time chart showing exclusive control for a plurality of nodes in the communication system shown in FIG. 7;
9 is a flowchart showing reception processing for a plurality of nodes by a communication driver of the programmable controller shown in FIG. 7;
FIG. 10 is a block diagram showing an example of a communication system that exchanges data using conventional cyclic communication (data link).
11 is a time chart showing the operation of the conventional communication system shown in FIG.
12 is a flowchart showing communication processing by a communication driver of a programmable controller in the conventional communication system shown in FIG.
13 is a flowchart showing communication processing by a communication controller in the conventional communication system shown in FIG.
[Explanation of symbols]
10 Programmable controller
11 User program
12 Communication driver
13 Cache memory
20 Shared memory
21, 211-1 to 21-n Communication data buffer
22-1 to 22-n reception flag
23-1 to 23-n Exclusive flag
24 Start flag
25 Completion 1 flag
26 Completion 2 flag
30 Communication controller
31 Receive buffer
32 Transmission buffer
40 Communication media

Claims (7)

A shared memory for exchanging data is connected between the communication controller connected to the communication medium containing a plurality of nodes and the terminal, and cyclically received from the communication medium via the communication controller. A data exchange method using cyclic communication, in which the received data is copied to the shared memory, and the received data copied to the shared memory is read in response to a read command from the terminal and delivered to the terminal. ,
The communication controller includes a reception data buffer for storing the reception data in units of nodes, and stores the reception data cyclically received from the communication medium in the reception data buffer in units of nodes.
The shared memory is a communication data buffer for storing received data in units of nodes, and a reception flag provided for each node and indicating whether the received data is stored in the communication data buffer in units of nodes. And the received data stored in the received data buffer of the communication controller is copied to the communication data buffer for each of the plurality of nodes,
Only when new reception data to be transferred to the terminal is stored in the communication data buffer of the shared memory and the reception flag indicates storage of reception data, the reception data is transferred from the communication data buffer of the shared memory to the terminal. A data exchange method characterized by enabling. The operation of reading the received data copied to the shared memory and delivering it to the terminal is as follows:
The data exchange method according to claim 1, wherein the data exchange method is performed via a cache memory provided in the terminal. The terminal
The data exchange method according to claim 1, comprising a programmable controller having a user program and a communication driver. The terminal
It consists of a programmable controller having a user program and a communication driver,
The cache memory is
3. The data exchange method according to claim 2 , wherein the data exchange method is provided in the communication driver. A shared memory for exchanging data between the communication controller and the programmable controller connected to a communication medium that accommodates a plurality of nodes is connected, and cyclically from the communication medium via the communication controller. A data exchange apparatus using cyclic communication that copies received data to the shared memory, reads the received data copied to the shared memory in response to a read command from the programmable controller, and delivers the read data to the programmable controller Because
The communication controller
A reception data buffer for storing reception data cyclically received from the communication medium in units of the nodes;
The shared memory is
A communication data buffer for storing the data to be exchanged in units of nodes;
Management means for managing exclusive processing of the exchanged data stored in the communication data buffer in units of nodes,
The management means is
A data exchange apparatus, comprising: a reception flag provided for each node and indicating whether or not the data to be exchanged is stored in the communication data buffer in units of nodes. The programmable controller is
A user program section for storing a user program;
A communication driver for communicating with the shared memory;
6. The data exchange device according to claim 5 , further comprising: The communication driver
A cache memory that once reads and stores the received data copied to the shared memory;
The data exchange apparatus according to claim 6 , further comprising:

Images