JP3129730B2 - Network communication method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention is connected to a main body of a programmable controller (hereinafter, referred to as a PC) and relays data between networks.
The present invention relates to a method for intercommunication between PC networks.

<Conventional technology> Conventionally, a method of intercommunication between networks in a PC includes:
Each communication unit connected to the PC performs relay between the PC and the network, and the MPU of the PC searches the routing table stored in the internal memory of the PC, and based on the routing table. Communication between networks.

The routing table is an address that indicates the communication path from the communication unit of the own PC to the communication unit of the final target PC that is the communication destination.For example, the network address of the network that passes between them and relays the networks The node address etc. of the communication unit (node) of the PC to be set are set.

<Problems to be Solved by the Invention> However, in the above-described inter-network communication method in the PC, the communication unit merely relays between the network and the PC main unit, and the MPU of the PC main unit is switched every time the routing is performed. The routing table stored in the internal memory of the PC was searched.

For this reason, the overhead of the PC system at the time of network relaying increases, and in particular, when network relaying simultaneously concentrates on PCs relaying many networks (hereinafter referred to as relay PCs), the load concentrates on the PC itself, There is a problem that the overhead of the system of the relay PC increases.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for inter-network communication between PCs in which the overhead of the PC system during network relay is not increased.

<Means for Solving the Problems> In order to solve the above problems, the present invention provides a programmable controller in which a plurality of communication units are mounted on a programmable controller main body, by connecting different networks to each of the plurality of communication units. An inter-network communication method for performing relay communication between the networks, wherein a routing table is provided in the programmable controller, and the routing table is connected to the unit identification information of each of the communication units and each of the communication units. A network address of a network is set, and at the time of relay communication between the networks, the first communication unit connected to the first network among the plurality of communication units determines a network address and a communication address of a communication unit of a transmission destination. Receiving the communication information including the communication information and the node address, searches the routing table and transfers the communication information to a second communication unit connected to a second network corresponding to the destination network address. The second communication unit having received the information searches the routing table,
The communication information is transmitted to a communication unit of the destination node address connected to the second network.

Also, the present invention provides a programmable controller (hereinafter, referred to as a PC) in which a communication unit is mounted on a main body of a programmable controller, wherein the communication unit is connected to an arbitrary network, and a communication unit of a similar separate PC is connected to another network. In addition, for relays with multiple communication units mounted on the programmable controller body
A method in which the plurality of communication units of a PC are connected to the arbitrary and different networks, respectively, and perform inter-network communication via the relay PC, wherein the PC and the relay PC are respectively routed. The routing table contains the final network address, relay network address, relay node address, and relay PC necessary for inter-network communication.
Network address and unit identification information of each communication unit necessary for the communication unit are appropriately set, and the communication unit searches the routing table of the PC by the communication unit on the PC performing the communication across the networks, thereby establishing the communication path. Judge and transmit the communication information from the communication unit of this PC to the relay PC in the same network connected to the communication unit, and the relay PC that has received the routing table of the relay PC. Search for the PC
The communication information is transmitted to a communication unit of a PC on a network different from the above-mentioned network by performing transfer between a plurality of communication units mounted on the PC.

<Operation> In the configuration of the present invention described above, using the routing table of a PC, communication information transfer processing between a plurality of relay communication units mounted on the PC, and communication between the separately connected PCs are performed.

<Embodiment> Hereinafter, an embodiment of an inter-network communication control system using a communication unit of a PC according to the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a state in which networks are connected by a communication unit of a PC according to the present invention. This relay PC 2 has two communication units A and B in addition to the PC main body 21. The networks X and Y are connected to the communication units A and B, respectively, and the number of relaying networks can be increased or decreased by increasing or decreasing the number of communication units. Although the PCs 1, 3, and 4 are not shown in the figure, each has a communication unit connected to the network X or Y.

Then, the PC main body 21 of the relay PC 2 of this embodiment and the communication unit A are configured and connected as shown in FIG. 2, and the communication unit B shown in FIG.
3, 4 PCs and their communication units are similarly configured,
It is connected.

That is, the PC body 21 has a CPU 25 having a DMA transfer function and an internal memory 22, as shown in FIG. The internal memory 22 has a backup memory 23 in which a routing table described later is set and stored, and the routing table is transferred from the backup memory 23 so that the routing table can be searched or referred to when the CPU 25 performs data communication. And an internal RAM 24. In addition, the PC main unit 21 includes a system program (not shown).
It also has a ROM, an input / output memory, and the like.

Further, the communication unit A has an interface function with the PC 2, and has a PC interface 31 having a shared RAM 32 provided with an event area for storing events transmitted and received with the PC 2, and an MPU 3 for controlling the inside of the unit.
3, a system program ROM (EP-ROM) 34 having a built-in communication system program, an internal RAM 35, a DPRAM 36 as a communication buffer, a communication controller 37, and a communication interface 38.

In the case of the communication unit A of the present embodiment, the internal RAM 3
5 is provided with an area for holding a routing table from the PC main body 21.

In the system program ROM 34, the MPU 33 is
Read the routing table from the internal memory 22 of 21,
A system program programmed to store it in the internal RAM 35, search the routing table stored in the internal RAM 35 as communication control means, and perform communication control between networks based on the routing table is built-in. ing.

In the figure, 39 is a peripheral interface (PPI), 40 is a PC
A switch 41 for setting unit identification information such as a machine number indicating an address of the communication unit A in the main body 21, and a display unit 41 for displaying the machine number, the operation state of the communication unit A, and the like.

Further, in this embodiment, the routing table corresponds to each PC.
Refers to a table for determining the relay route (communication route) when using the network relay function,
Programming tool (not shown) in advance by the user
Alternatively, it is set by the host computer (not shown), and is first stored in the backup memory of each PC main body as described above, and thereafter read out from the backup memory, and stored in the internal RAM of the PC main body and the internal RAM of the communication unit. Is forwarded to

That is, in this embodiment, the setting and the change of the routing table from the programming tool or the like to the backup memory are performed by the setting command. At that time, the parameter writing (routing designation) and the routing table writing are performed in one action. However, before writing to the parameter area, the presence / absence of the time network table and the set number are checked, that is, the set number is checked to be 0 or the MAX number. If an error occurs, an error response is returned and the backup memory is returned. Do not write to.

Next, for example, in the PC body 21 as shown in FIG.
5 transfers the routing table in the backup memory 23 to the internal RAM 24 by a transfer command so that the routing table has a double structure. At this time, a sum value check, a check of the presence / absence of the setting, and a check of the set number are performed.

Then, transfer of the routing table on the PC main body 21 side
After writing is completed, communication units A and B restart (RESTA
RT), and reads the routing table from the internal RAM 24 on the PC main body 21 side.

In other words, the MPUs 33 on the communication units A and B read the value of the routing table from the internal RAM 24 on the PC main body 21 by the parameter READ, and reflect errors such as an abnormal sum value and an invalid table (no registration table). Write to the internal RAM 35 in the communication units A and B, and connect the PC unit 21 and the communication units A and B
Simultaneity of both routing tables is to be achieved between the two.

As described above, in the present embodiment, the routing table is not immediately enabled at the time of setting, but is checked at the time of setting and transfer, and is set and transferred after being enabled. Simultaneity between the routing table and the routing table operating on the communication unit side is ensured.

Further, in the present embodiment, the routing table comprises a relay table 51 as shown in FIG. 3 and a local network table 61 as shown in FIG.

The relay table 51 is a table for determining the transmission route of the communication unit of the own PC, and is set when the final network to be the destination is other than the own network. As shown in FIG. The final network address, the network address of the relay network, and the node address of the relay network are set for each set network. For example, a network as shown in FIG. 4 has a configuration as shown in FIG.

In the own network table 61, a network address of a network connected to the relay PC (hereinafter referred to as own network address) and a machine number NO (unit identification information) of a communication unit directly connected to the network are set. The table is set together with the set network number and the number of times of passing through the gateway as shown in FIG. 6, and the relay PC between the connected networks as shown in FIG. 7 has a configuration as shown in FIG. .

Next, the operation of the thus configured PC communication unit will be described mainly with reference to FIG. 1 and FIG.

However, as shown in FIG. 1, two networks X, Y
Are connected via the communication units A and B of the relay PC 2, perform network relay using the event transfer function of the communication units A and B, and communicate from the PC 1 of the network X to the PC 3 of the network Y And

First, as shown in FIG. 1, the user first communicates with the PC1 by using the communication unit of the own PC1 (not shown) and the communication unit of the final target PC3 (not shown) by the PC1.
The network address and the node address are designated by a command, and the command is transmitted via the communication unit of the PC1.

Then, the MPU of the communication unit of the PC1 searches the routing table stored in the internal RAM of the communication unit from the command, determines that the command is transferred to the communication unit A,
The command is transferred to the communication unit A.

At that time, the command causes the communication unit A shown in FIG. 2 to enter a communication service (FINS) command area as shown in FIG. 9 in the event area of the shared RAM 32.
Number of gateway passes (GCNT), network address (DNA) and node address (DA1) of the final target, ie, the destination communication unit of PC3 which is the destination node
And its machine NO (DA2) are set, and the network address (SNA) and node address (SA1) of the communication unit of PC1, which is the sender node, its sender machine NO (SA2), and the requester Communication information such as a service ID (SID), a data part (DATA), etc., which are identifiers for identifying the process.

Then, as shown in FIG. 2, the MPU 33 of the communication unit A searches the routing table stored in the internal RAM 35 of the own communication unit A, determines that the transfer is to the communication unit B, and sets the destination unit to the communication unit B, The source unit is the communication unit A, and each unit NO is connected to the PC interface.
Among the event areas as shown in FIG. 9 provided in the shared RAM 32 of FIG.
Set in an event area like.

Next, the CPU 25 of the PC body 21 is connected to the shared RAM of the communication unit A.
It was determined that the transfer was made from the destination machine No. written in the event area of No. 32 to the communication unit B, and the event of the communication unit A was provided in the shared RAM in the PC interface of the communication unit B as shown in FIG. DMA in event area
Forward.

Then, the MPU of the communication unit B also searches the routing table stored in the internal RAM of the communication unit B, and
It is determined that the transfer is to the communication unit of C3, and the above event is transferred from the event area provided in the shared RAM in the communication unit B to the communication unit of PC3 via the communication interface.

Finally, the communication unit of the PC 3 can receive the event in which the communication service command as shown in FIG. 9 is written, together with the source machine NO and the destination machine NO.

Therefore, in this embodiment, the communication unit searches the routing table during communication between networks,
The main unit does not search the routing table but only performs DMA transfer of commands between communication units.

For this reason, only the routing table is searched.
Since the load on the PC itself is distributed to the communication unit side, even when the relay PCs perform a large number of network relays and network relays are concentrated, the overhead of the PC itself is reduced and the overall throughput of the communication system is improved. .

Further, in this embodiment, since the MPU of the communication unit performs the search processing of the routing table, if the command received by the communication unit is a routing error, an error response can be made within the communication unit, and the communication between the communication unit and the PC main body can be performed. This eliminates the need for command transfer, and further reduces the load on the PC itself.

In addition, the PC main unit and the communication unit will each have a routing table.In the PC main unit, the above-mentioned check is performed when setting to the backup memory and when transferring from the backup memory to the internal RAM.
Also, the same check is performed when transferring data from the PC to the communication unit, so that the synchronization of the routing tables can be guaranteed.

In this embodiment, two communication units have been described.
In the present invention, three or more communication units are connected to the PC body,
Of course, the present invention is also applied to a case where three or more networks are relayed. In this case, the communication unit of the PC searches the routing table and controls communication with the network based on the routing table. Between commands
Since only the DMA transfer is performed, the overhead in the PC itself is reduced, and the throughput of the entire system is improved.

<Effects of the Invention> As described above, according to the present invention, when performing relay communication between networks,
Communication information is transferred between the communication units of the PC, and the communication unit on the transfer side and the communication unit on the transfer side search the routing table for each and select the communication route. Without interfering with the execution of various functions, it is possible to efficiently perform inter-network communication between PCs connected to different networks,
In addition, the overhead of the PC body is reduced, and the throughput of the entire communication system is improved.

If the command received by the communication unit is an error, the communication control means of the communication unit responds with an error, eliminating the need for command transfer between the communication unit and the PC, further reducing the load on the PC can do.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a state in which networks are connected by a communication unit of a PC according to the present invention, and FIG.
FIG. 3 is a block diagram showing the configuration and connection state between the PC main unit and the communication unit of the PC, FIG. 3 is a table memory showing the configuration of the relay table, FIG. 4 is a block diagram showing an example of connection between networks, and FIG. FIG. 4 is a table memory showing a relay table of each PC in FIG. 4, FIG. 6 is a table memory showing a configuration of its own network table, FIG. 7 is a block diagram showing an example of a configuration of a relay PC connecting a network,
FIG. 8 is a table memory showing the configuration of the own network table of the relay PC in FIG. 7, and FIG. 9 is a table memory showing the configuration of the event area. 1,2,3,4 ... PC (programmable controller) 33 ... MPU (communication control means) 35 ... Internal RAM (storage means) A, B ... communication unit X, Y, Z ... network

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04L 12/28 H04L 12/46 H04L 12/56 H04L 12/66 G05B 19/05

Claims (2)

(57) [Claims] In a programmable controller in which a plurality of communication units are mounted on a main body of a programmable controller, a different network is connected to each of the plurality of communication units, and an inter-network mutual communication method for performing relay communication between the networks. A routing table is provided in the programmable controller, and unit identification information of each of the communication units and a network address of a network connected to each of the communication units are set in the routing table. Receiving a communication information including a network address and a node address of a communication unit of a transmission destination when a first communication unit connected to a first network among the plurality of communication units receives the communication information. The communication table is searched, and the communication information is transferred to a second communication unit connected to a second network corresponding to the destination network address. A method for inter-network communication, comprising: searching a table; and transmitting the communication information to a communication unit of the destination node address connected to the second network. 2. The communication unit of a programmable controller (hereinafter, referred to as a PC) having a communication unit mounted on a main body of the programmable controller is connected to an arbitrary network, and the communication unit of a similar separate PC is connected to another network. Further, the plurality of communication units of the relay PC in which a plurality of communication units are mounted on the main body of the programmable controller are respectively connected to the arbitrary and different networks, and the inter-network mutual communication is performed via the relay PC. A routing table is provided for each of the PCs and the relay PCs, and the routing tables include a final network address, a relay network address, a relay node address, and a relay PC required for inter-network communication. Each communication unit required The network address and own unit identification information are appropriately set, and the communication unit determines the communication path by searching the routing table of the PC by the communication unit, which performs communication over the network. For relaying from the unit to the communication unit within the same network connected to the communication unit
By transmitting the communication information to the PC, the received relay PC searches the routing table of the relay PC, and performs the transfer between the plurality of communication units mounted on the PC. An inter-network communication method, comprising transmitting communication information to a communication unit of a PC on a network different from the network.