JP4026817B2 - Communications system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a communication system using an AV / C command in a network through communication other than IEEE 1394 between networks connected by IEEE 1394.
[0002]
[Prior art]
In recent years, IEEE 1394 has attracted attention as a standard interface for digitally connecting home AV equipment. Attempts have also been made to construct a network in a wider range in the home using technologies such as Wireless 1394 and 1394 over 802.11 for wirelessly connecting networks configured with IEEE 1394.
[0003]
There are IEEE 1394 devices at both ends, and there are the following conventional examples of device control methods using AV / C commands in networks other than IEEE 1394 such as wireless communication.
[0004]
According to Patent Document 1 and Patent Document 2, a technique for controlling a device using an AV / C command wirelessly is described. In this conventional example, an AV / C command sent from an IEEE 1394 device to a wireless node is placed in an FCP frame, encapsulated in an IEEE 1394 packet, converted into a packet on IEEE 802.11, and transferred over the air (bus bridge). . The base station that has received this packet takes out an FCP frame from the IEEE 802.11 protocol, and uses a method of allocating devices to be controlled based on destination Subunit information included in the AV / C command frame therein. . Here, Subunit is a functional unit component in the world of AV / C commands.
[0005]
[Patent Document 1]
JP 2000-115173 A [Patent Document 2]
Japanese Patent Laid-Open No. 2000-196618 [0006]
[Problems to be solved by the invention]
However, when connecting IEEE 1394 and IEEE 802.11 as in the above-described apparatus, a bus bridge technique is required for conversion of communication means between IEEE 1394 and IEEE 802.11. Since IEEE 1394 equipment already on the market does not support the bus bridge technology, there is a problem that it is difficult to control the equipment with AV / C commands between networks across the bridge.
[0007]
In addition, a method for determining a device to be controlled based on controlled Subunit information is for a user who controls which Subunit corresponds to which device when a plurality of devices having the same Subunit exist on the network. There is a problem of not knowing. Furthermore, since IEEE 1394 equipment already on the market selects a control target on a node basis, it has a problem that it is difficult to control from existing equipment using AV / C commands.
[0008]
The present invention has been made in view of such a situation, and even when existing IEEE 1394 devices are connected by a heterogeneous network such as wireless communication, the FCP frame itself does not depend on a specific communication protocol. By transferring, the IEEE 1394 device on the network can be controlled by the AV / C command included in the FCP frame. It is another object of the present invention to reduce network traffic by transferring only a frame FCP including an AV / C command among various FCP frames to the network.
[0009]
[Means for Solving the Problems]
The present invention provides means for solving these problems, and the invention of each claim constitutes the following technical means.
[0011]
A communication system according to the present invention is a communication system in which a plurality of networks constructed by a first communication protocol and a plurality of networks are connected by a second communication protocol, and the first communication protocol is IEEE1394. Yes, the second communication protocol is a communication protocol other than IEEE 1394, and the plurality of networks confirm the AV / C command from a specific bit of the data field in the FCP frame, and only in the case of the AV / C command, the FCP The communication is performed by placing the frame on the second communication protocol.
[0017]
More specifically, there are a network 1 and a network 2 to which devices having an IEEE 1394 interface are connected. Furthermore, there is a network 3 that connects these two networks by a communication means other than IEEE1394. Each of the networks 1 and 2 is connected to one of communication terminals of the network 3 through an IEEE 1394 interface.
[0018]
Let us consider a case where a controller belonging to the network 1 controls a target belonging to the network 2 with an AV / C command. At this time, the controller sends an AV / C command in the form of an FCP frame to a virtual node existing on a communication terminal connected to the network 1 based on the IEEE 1394 specification. Here, the virtual node is obtained by virtually reproducing the target node belonging to the network 2 on the communication terminal of the network 1, but the reproduction method is not described in this specification. The AV / C command thrown to the virtual node is transferred to the communication terminal of the network 2 in the form of an FCP frame regardless of the protocol of the communication path between them, and is sent to the actual target in accordance with the IEEE 1394 specification. Is passed. The target transmits a response to the received AV / C command to the controller in the same manner.
[0019]
This allows AV / C commands to be exchanged in the same way as when the controller and target are both directly in the same network, regardless of the communication path other than IEEE 1394 between them. This makes it possible to use existing IEEE 1394 equipment.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
An example of an embodiment of a communication system according to the present invention will be described below with reference to FIGS.
[0021]
FIG. 1 shows an example of the configuration of an embodiment of a communication system according to the present invention, which is composed of an IEEE 1394 network 1 (101), an IEEE 1394 network 2 (102), and a network (103) other than IEEE 1394.
[0022]
Consider a case where an AV / C controller (hereinafter referred to as node A) (111) belonging to the IEEE 1394 network 1 (101) controls an AV / C target (hereinafter referred to as node B) (112) belonging to the IEEE 1394 network 2 (102). And
[0023]
On the communication terminal 1 (131) connected to the node A and the IEEE 1394, the virtual target of the node B (hereinafter referred to as the node B ′) (141) is placed on the communication terminal 2 (132) connected to the node B and the IEEE 1394. The virtual controller of node A (hereinafter referred to as node A ′) (142) is configured by communication between the respective communication terminals. At this time, node A (111) sees node B ′ (141) on the same network, and node A (111) recognizes node B ′ (141) as a control target. As a result, the node A (111) controls the devices on the same network as if the AV / C command shown in FIG. 3 in the data field of the FCP frame shown in FIG. 2 for the node B ′ (141). Send a frame.
[0024]
The node B ′ (141) that has received the command identifies the destination_ID that is the destination of the received FCP frame, and if it recognizes that the destination_ID is addressed to itself, the node B ′ (141) sends an Ack response indicating that the packet has been received to the node A ( 111). If the node A (111) does not receive the Ack response, it retransmits the FCP frame.
[0025]
Asynchronous communication on the IEEE 1394 bus is based on a pair of transaction of request and response for one communication. Therefore, by returning an Ack response at the node B ′ (141), traffic in networks other than IEEE 1394 is reduced thereafter. I can do it.
[0026]
Further, it is confirmed that the first 4 bits of the data field in the received FCP frame (cts field of the AV / C command frame) are all 0, whether it is an AV / C command. The frame is passed to the communication unit 1 (151). Since the FCP frame may include data other than the AV / C command, traffic in a network other than IEEE 1394 can be reduced by limiting the transmission target to only the FCP frame including the AV / C command. I can do it.
[0027]
The communication unit 1 (151) transmits the received FCP frame as it is on the communication protocol of the network (103) other than IEEE1394 to the communication unit 2 (152) of the communication terminal 2 (132) of the IEEE1394 network 2 (102). . Since the FCP frame is simply a data chunk, when only the FCP frame is transferred, the FCP frame can be transmitted without requiring a complicated mechanism such as a bus bridge.
[0028]
Here, Node B '(141) that is managed in advance by any IEEE1394 communication or information networks belonging terminal 1 (131) in the AV / C command even if a plurality of IEEE1394 network is connected transmitted The command can be accurately sent to the node B (112).
[0029]
When the communication unit 2 (152) of the communication terminal 2 (132) takes out the received FCP frame, identifies the source_ID field in the FCP frame, and if it is found that the AV / C command is from the node A (111), The FCP frame is passed to the node A ′ (142).
[0030]
When the node A ′ (142) identifies the destination_ID of the received FCP frame and recognizes that the destination_ID is the node B (112), the node A (142) is as if it were the node A (111). The FCP frame containing the AV / C command is transferred.
[0031]
Upon receiving the AV / C command, the Node B (112) identifies the destination_ID that is the destination of the received FCP frame, and if it recognizes that the destination_ID is addressed to itself, it sends an Ack response indicating that the packet has been received. Return to A '(142). If the node A ′ (142) does not receive the Ack response, the node A ′ (142) retransmits the FCP frame.
[0032]
Asynchronous communication on the IEEE 1394 bus is based on a pair of transaction of request and response for one communication, so that the node B ′ (141) receives an Ack response to reduce traffic in networks other than IEEE 1394 thereafter. I can do it.
[0033]
The node B (112) receiving the FCP frame including the AV / C command can see the node A ′ (142) on the same network, and the AV / C command is transmitted from the node A ′ (142). As a response to the AV / C command received to the node A ′ (142), the AV / C response frame shown in FIG. 4 is added to the data field of the FCP frame shown in FIG. 2 within 100 ms. Put it on and send it.
[0034]
The node A ′ (142) that has received the response identifies the destination_ID that is the destination of the received FCP frame, and if it recognizes that the destination_ID is addressed to itself, it sends an Ack response indicating that the packet has been received to the node B ( 112). When the node B (112) does not receive the Ack response, it retransmits the FCP frame.
[0035]
Asynchronous communication on the IEEE 1394 bus is based on a pair of transaction of request and response for one communication. Therefore, by returning an Ack response at the node A ′ (142), traffic in a network other than IEEE 1394 is reduced thereafter. I can do it.
[0036]
Further, the first 4 bits of the data field in the received FCP frame (the cts field of the AV / C response frame) is confirmed to be an AV / C response based on whether it is all 0, and only in the case of an AV / C response, the FCP The frame is passed to the communication unit 2 (152). Since the FCP frame may contain data other than the AV / C response, traffic in a network other than IEEE 1394 can be reduced by limiting the transmission target to only the FCP frame including the AV / C response. I can do it.
[0037]
The communication unit 2 (152) carries the received FCP frame as it is on the communication protocol of the network (103) other than IEEE1394 and transmits it to the communication unit 1 (151) of the communication terminal 1 (131) of the IEEE1394 network 1 (101). . Here, the node A '(142) that is managed in advance by any IEEE1394 network belonging or information communication terminal 2 (132) in the AV / C command even if a plurality of IEEE1394 network is connected transmitted It is possible to accurately return a response to the node A (111).
[0038]
When the communication unit 1 (151) of the communication terminal 1 (131) takes out the received FCP frame, identifies the source_ID field in the FCP frame, and when it is found that the AV / C response is from the node B (112), The FCP frame is passed to the node B ′ (141). When the node B ′ (141) identifies the destination_ID of the received FCP frame and recognizes that the destination_ID is the node A (111), the node B (111) is as if it were the node B (112). The FCP frame including the AV / C response is transferred.
[0039]
The node A (111) that has received the AV / C response identifies the destination_ID that is the destination of the received FCP frame, and if it recognizes that the destination_ID is addressed to itself, the node A (111) sends an Ack response indicating that the packet has been received. Return to B '(141). If the node B ′ (141) does not receive the Ack response, it retransmits the FCP frame.
[0040]
Asynchronous communication on the IEEE 1394 bus is based on a pair of transaction of request and response for one communication, so that the node B ′ (141) receives an Ack response to reduce traffic in networks other than IEEE 1394 thereafter. I can do it.
[0041]
The node A (111) can know the result of the AV / C command transmitted to the node B (112) according to the content of the received AV / C response.
The sequence of the above operation is shown in the sequence diagram of FIG. An AV / C response corresponding to the AV / C command issued from the node A (111) to the node B ′ (141) is returned from the node B ′ (141) to the node A (111).
[0042]
An AV / C response corresponding to the AV / C command issued from the node A ′ (142) to the node B (112) is returned from the node B (112) to the node A ′ (142). Yes. As a result, the node A (111) and the node B (112) seem to have completed transmission / reception of AV / C commands and AV / C responses in the IEEE 1394 network which is a closed system.
[0043]
For this reason, control is performed for nodes such as existing IEEE 1394 devices, and devices that are not compatible with other network controls can also be used. In addition, since communication is unidirectional in systems other than the IEEE 1394 network, communication traffic can be reduced.
[0044]
【The invention's effect】
The following effects are brought about by the present invention described above.
[0045]
Since the communication system according to the present invention is configured as described above, it is possible to control devices using AV / C commands between a plurality of IEEE 1394 networks via different communication means.
[0046]
In addition, AV / C commands can be transmitted and received between a plurality of networks.
[0047]
In addition, since the configuration is as described above, it is possible to transmit / receive AV / C responses between a plurality of networks.
[0048]
Further, since the configuration is as described above, it is possible to use AV / C commands without using a bridge to a specific communication protocol.
[0049]
Further, since the configuration is as described above, the AV / C command can be carried in the FCP frame.
[0050]
Further, since the configuration is as described above, it is possible to reduce network traffic by carrying only FCP frames including AV / C commands.
[0051]
Further, since the configuration is as described above, it can be controlled and controlled by existing IEEE 1394 equipment.
[Brief description of the drawings]
FIG. 1 is a functional block diagram showing an embodiment of a device control method according to the present invention.
FIG. 2 is a diagram illustrating a configuration of an FCP frame.
FIG. 3 is a diagram illustrating a configuration of an AV / C command frame.
FIG. 4 is a diagram illustrating a configuration of an AV / C response frame.
FIG. 5 is a sequence diagram showing an embodiment of a device control method according to the present invention.
[Explanation of symbols]
101 IEEE 1394 network 1
102 IEEE 1394 network 2
103 Network 111 other than IEEE 1394 AV / C controller (node A)
112 AV / C target (Node B)
121 IEEE 1394 bus 1
122 IEEE 1394 bus 2
131 Communication terminal 1
132 Communication terminal 2
141 Virtual target (Node B ′)
142 Virtual Controller (Node A ′)
151 Communication unit 1
152 Communication unit 2

Claims (1)

A plurality of networks constructed by a first communication protocol, and a communication system for connecting the plurality of networks by a second communication protocol,
The first communication protocol is IEEE 1394,
The second communication protocol is a communication protocol other than IEEE 1394,
The plurality of networks confirms an AV / C command from a specific bit of a data field in an FCP frame, and communicates the FCP frame on the second communication protocol only in the case of the AV / C command. Communication system.

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