JPH07131470A - Communication system and communication equipment used for the same - Google Patents

Abstract

PURPOSE:To prevent a logical address from changing when the communication system is reset without altering the constitution of the communication system by providing each node with a means which stores the logical addresses of this node and other nodes. CONSTITUTION:The address table 6 of a digital VTR uses part of the RAM of a microcomputer 5 and stores the physical addresses of other nodes connected to the digital VTR and a P1394 bus, and logical addresses, etc., including article categories. The contents of the address table 6 are read and written by an addressing program 7. Further, the addressing program 7 inquires about the addresses of other nodes connected to the P1394 bus, sends and receives response commands, and confirms the physical address and logical address of this node thorugh a digital I/F. Therefore, when the communication system is reset, original logical addresses, e.g. numbers by article categories can automatically be allocated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention connects AV equipment such as a digital VTR, a television receiver (hereinafter abbreviated as TV), and a tuner to a bus, and transmits digital video signals, digital audio signals, and the like between them. The present invention relates to a communication system for transmitting and receiving.

[0002]

2. Description of the Related Art A communication system in which AV equipment such as digital VTR, TV, tuner, personal computer, etc. are connected to an IEEE 1394 bus (hereinafter referred to as P1394 bus), and digital video signals, digital audio signals, etc. are transmitted and received between these equipments. Is being considered.

FIG. 16 is a diagram showing an example of such a communication system. This communication system includes a root node A, a leaf node B, a branch node C, a leaf node D, and a leaf node E. Then, nodes A-B, A-C, C-D, and C-E.
The input / output ports between are connected by two twisted pair cables. The nodes A to B are, as described above,
A digital VTR, TV, tuner, personal computer, etc., each having one or more input / output ports. Since each node has an amplifier and a repeater built therein, the communication system in FIG. 16 is equivalent to the communication system in which each node is connected to the bus as shown in FIG.

In FIG. 16, a hierarchical structure is formed in which nodes B and C are connected below node A, and nodes D and E are connected below node C.
In other words, node A is the parent node of nodes B and C, and node C is the parent node of nodes D and E. First, the procedure for determining this hierarchical structure will be described.

When the nodes A-B, A-C, C-D, and C-E are connected by a cable, the node having only one input / output port connected to another node The fact that the other party is the parent node is transmitted to the connected node. In the case of FIG. 14, the nodes D and E are the nodes C.
To node A, node B transmits to node A that node A is a parent node.

A node having a plurality of input / output ports connected to another node is a parent node to a node other than the node that has transmitted the fact that it is a parent node to itself. Communicate to the effect. In the case of FIG. 16, the node C notifies the node A that the node A is the parent node, and the node A notifies the node C that the node C is the parent node. At this time, node A and node C
Between the two nodes, the fact that the partner node is the parent node is transmitted to each other, and the node that has been previously transmitted that the parent node is the parent node becomes the parent node. 16 shows node A
Shows the case where becomes a parent node.

Next, a procedure for giving a physical address to each node will be described. The physical address of a node is basically obtained by allowing the parent node to give the child node an address. If there are multiple child nodes,
For example, the permission is given in order from the child node connected to the smaller port number.

In FIG. 16, when node B is connected to the port of node A and node C is connected to the port, node A permits node B to assign an address. The node B assigns itself the node ID # 0 and sends data indicating that it assigns the node ID # 0 to the bus. Next, the node A permits the node C to determine the address. The node C permits the node D connected to the port to assign an address. The node D gives itself a node ID # 1. Next, the node C permits the node E connected to the port to assign an address. The node E gives the node ID # 2 to itself. Node C is child node D and E
When the address assignment is completed, the node ID # 3 is assigned to itself. When the node A completes the address assignment of the child nodes B and C, it assigns the node ID # 4 to itself.

In this communication system, as shown in FIG. 18, communication is performed in a communication cycle having a predetermined cycle (for example, 125 μs). There is a cycle start packet csp at the beginning of the communication cycle, and a period for transmitting a packet for synchronous communication is set subsequently to the cycle start packet csp. It is possible to perform a plurality of synchronous communications by assigning channel numbers 1, 2, 3, ... N to each packet for performing the synchronous communication. For example, if channel 1 is assigned to the communication from the node B to the node C, the node B sends the cycle start packet cs
Immediately after p, the synchronous communication packet with the channel number 1 is transmitted, and the node C monitors the bus, and the channel number 1
Communication is performed by capturing a synchronous communication packet with. Similarly, channel 2 can be allocated for communication from node D to node A, for example. Also,
It is also possible for multiple nodes to receive the packet of one channel.

When a plurality of synchronous communications are carried out, transmission of the synchronous communications packets of a plurality of channels is tried immediately after the cycle start packet csp. In that case, arbitration means (eg CSMA / C
According to D), the synchronous communication packet of one channel is transmitted first, and then the synchronous communication packets of the other channels are sequentially transmitted.

After the transmission of the synchronous communication packets of all channels is completed, the period until the next cycle start packet csp is used for asynchronous communication. Asynchronous communication packets (packets A and B in FIG. 18) have addresses of the transmitting node and the receiving node, and each node takes in the packet having its own address.

As described above, in this communication system, synchronous communication for continuously communicating at a constant data rate like a digital video signal, and asynchronous communication for transmitting control commands and the like irregularly as needed. You can do both. For details on the above communication and the method of automatically assigning addresses to each node, see "IEEEP".
Since it has been published as a "1394 serial bus specification," it will not be described further here.

[0013]

However, in the communication system configured as described above, the first digital VTR is used instead of the physical addresses such as # 0 to # 4.
(Hereinafter referred to as VTR1), second digital VTR
(Hereinafter referred to as VTR2), the first TV (hereinafter referred to as TV1)
It is not possible to assign a logical address that includes a product category such as).

As a system capable of performing addressing including a product category for a node in a communication system, a D2B (Domestic D)
digital bus).

In D2B, each node is, for example, T
It is configured so that it declares from itself that it will assign an address in the 10's range for V and an address in the 20's range for a digital VTR. Then, when the communication system is reset, the logical address allocation is performed on a first-come-first-served basis. For example, the VTR 1 sends a command asking whether there is a node with the logical address 20 on the bus, assigns the logical address 20 to itself if there is no response, and if there is a response, asks if there is a node with the logical address 21 next. Send the inquiring command and process it in the same way. If multiple nodes try to declare at the same time, wait a random time and then declare again. Therefore, there is no guarantee that the same logical address as before reset will be given to each node even if the physical connection state between nodes does not change as in the case where the communication system is reset by unplugging the power outlet. .

Further, in D2B, each node does not know how many nodes of which product category are connected to the bus. Therefore, for example, the digital VTR of the logical address 20 is replaced with another digital VTR.
When sending a command to the device, it was necessary to sequentially send a command in which the logical address was incremented by 1 from 21 until a reply was received from the other party.

The present invention has been made in order to solve such a problem, and provides a communication system configured such that a physical address is automatically assigned to each node according to a connection state between the nodes. The purpose is to prevent the logical address from changing when the communication system is reset without changing the configuration of the communication system such as when the power outlet is unplugged.

Further, according to the present invention, in a communication system configured such that a physical address is automatically assigned to each node in accordance with a connection state between the nodes, how many nodes having any logical address are connected to a bus. The purpose is to make it possible for each node to know whether it is being done.

[0019]

In order to solve the above-mentioned problems, the present invention provides a communication system configured so that a physical address is automatically assigned to each node according to a connection state between nodes. The node is provided with means for storing the logical addresses of itself and other nodes.

When the communication system is reset, each node retains its own logical address, so that the same logical address as before the reset is assigned to each node.

[0021]

According to the present invention, since each node has means for storing the physical address and logical address of another node, it is necessary to grasp what logical address node is connected to the bus. There is. Also, each node retains its own logical address when the communication system is reset.

[0022]

Embodiments of the present invention will now be described in detail in the order of [1] to [4] below with reference to the drawings. [1] Basic configuration of communication system [2] When node is added to communication system [3] When plural communication systems are combined [4] Control of device based on logical address

[1] Basic Configuration of Communication System FIG. 1 is a block diagram showing a basic configuration of a digital VTR which is an example of a communication device serving as a node in the present invention. FIG. 1A shows a hardware configuration. FIG. 1B shows a configuration related to addressing.

The digital VT shown in FIG. 1 (a)
R is a deck block 1 which is a basic block as a VTR
In addition to the tuner section 2, a digital interface (hereinafter referred to as a digital I / F) 3 for the P1394 bus, a deck section 1, a tuner section 2, a digital I
A switching box 4 for switching signals between F3 and F3 and a microcomputer 5 for system control are provided.

As shown in FIG. 1B, this digital VTR has an address table 4. This address table 6 uses a part of the RAM (not shown) of the microcomputer 5, and the digital VTR and P
It stores physical addresses of other nodes connected to the 1394 bus, logical addresses including product categories, and the like. The contents of the address table 6 are read and written by the addressing program 7. In addition, the addressing program 7 inquires an address to another node connected to the P1394 bus, transmits / receives a reply command, and confirms the physical address and logical address of the self node via the digital I / F.

When the communication device is a TV, a monitor section and an amplifier section are provided instead of the deck section 1. Also,
A microcomputer dedicated to communication control may be provided in the communication device, and an address table may be provided in this.

FIG. 2 is a diagram showing an example of the structure of a packet in the digital I / F. This packet is composed of a destination ID, a source ID, a digital I / F main address, a digital I / F sub address, a command, and the like. The destination ID is the physical address on the destination P1394 bus, and the source ID is the source P
It is a physical address on the 1394 bus. The digital I / F main address is the digital I / F of the sender.
The digital I / F sub address is a logical address on the digital I / F of the transmission destination. Then, the transmission command or the like is a command for inquiring the destination of a logical address or a reply to an inquiry of the logical address.

[2] When a Node is Added to the Communication System FIG. 3 is a diagram showing an example of a communication system to which the present invention is applied, and FIG. 3 (a) is the original system.
FIG. 3B shows a system in which one digital VTR is added to FIG.

First, in the communication system of FIG. 3A, a node is a first personal computer (hereinafter referred to as PC1), a TV.
1, VTR1 and VTR2, which are P1
It is connected to the 394 bus. It is assumed that the node IDs # 0 to # 3 as shown in the figure are assigned to each node. Each node other than the PC 1, that is, the AV device, has a product category number TV1, VTR as a logical address including the product category as shown in the figure.
1 and VTR2 are allocated (allocation procedure will be described later).

At this time, the contents shown in FIG. 4A are stored in the address tables of the TV1, VTR1 and VTR2. Here, the node ID is the physical address of each node described above. The digital I / F support is data indicating whether or not each node is an AV device that transmits and receives video data and audio data in this communication system. AV compatible with P1394 bus
Vendo in the ID area of the ROM is pre-installed on the device.
Since the sales source and the product name of the AV device are written in r Id, it is identified by the read packet of the P1394 bus whether or not the digital I / F is supported. Further, the category No. Is a product category number.

Next, consider the state (FIG. 3B) in which another digital VTR is connected to the VTR 2 from this state. At this time, the bus is reset, and the node IDs # 0 to # 4 shown in FIG. 3B are automatically assigned to each node. Further, the data indicating whether or not each node is compatible with the digital I / F and the product category number are held only for the own data, and the data for the other nodes are cleared. Therefore, the bus is reset,
At the time when the physical address is automatically assigned, the node ID = # 1, that is, the contents of the address table of the VTR1 before reset are as shown in FIG. 4 (b). Although not directly related to this embodiment, when it is removed from the communication system, its own node ID is # 0 and the category number is # 0, as shown in FIG. Holds only product categories.

Next, the product category-numbers shown in FIG. 3B are eventually assigned to each node. The assignment procedure will be described below. Although each node independently executes the following logical address allocation procedure after the bus reset, the operation of the VTR 1 before reset will be described here as an example.

First, the VTR1 is the above-mentioned Vendor.
Each node reads digital I / F by reading Id
A packet having a command for identifying the logical address and inquiring the logical address is transmitted to all the nodes corresponding to the digital I / F. The packet transmitted to the node having the node ID # 4 in FIG. 3B is as shown in FIG.
Here, since the logical address of the transmission destination is not yet known, it is assumed to be broadcast communication (broadcast). In response to this inquiry packet, the node whose node ID is # 4 transmits the reply packet shown in FIG. 5 (b). Similarly, the VTR 1 has a node ID # 2 and a node ID # 2.
A packet for inquiring the logical address is transmitted also to the node of 3. If the logical address returned from each node is equal to the expected logical address, the VTR 1 determines this logical address as the partner's logical address.

According to the above procedure, the VTR 1 can know the logical address of each node corresponding to the digital I / F, but the category undetermined address is returned from the node to which the logical address is not yet assigned.
FIG. 6 shows the contents of the address table in which the addresses of the respective nodes thus examined are written. Here, a case is shown in which a category-specific address undetermined code is returned from the node whose node ID is # 2.

Next, a procedure in which the node having the node ID # 2 allocates its own logical address will be described. The node having the node ID # 2 also identifies whether or not the other nodes support digital I / F by the same procedure as the VTR 1, and inquires the logical addresses of all the nodes corresponding to digital I / F. Then, if the user's own address is undecided, the addresses are assigned in the ascending order of free numbers in the same product category. However, if there is a node whose node ID is smaller than that of its own and an address of which is undecided in the same product category, it is assumed that logical addresses are assigned in ascending order of the node ID, and its own address is determined.
Therefore, as a result of inquiring about the logical addresses of other nodes, if the result is as shown in FIG. 7, the VTR 3 is assigned to itself.

[3] When a plurality of communication systems are combined Next, two communication systems in which a node address and a logical address are allocated as shown in FIG. 8A are shown in FIG.
A procedure for assigning logical addresses in the case of combining as shown in (b) will be described.

When the bus is reset, the node address shown in FIG. 8B is automatically assigned. At this time, as described above, each node basically holds its own logical address. However, when there is a node that has returned the same logical address as itself in the system, it judges whether or not its own node ID is the smallest. Then, the logical address is allocated to the node having the smallest node ID, and the other nodes are reallocated as the numbers are undecided.

For example, in FIG. 8B, the node ID
Since the node with # 3 and the node with node ID # 1 both retain VTR1 as a product category number after reset, the node with a node ID # 1 uses the product category number as its logical address. Confirmed,
The node with the node ID # 3 clears the product category number and allocates the same product category in ascending order of the available numbers.

Therefore, as the content of the address table of the node with the node ID # 3, the product category number returned from the node with the node ID # 1 is valid as shown in FIG. Assign if,
When inquiring about the logical address of each node, FIG.
As shown in FIG. 9C, if the category-undetermined address undecided code is returned from the node having the node ID # 1 as in (b) and the VTR2 is held as the product category-specific number, as shown in FIG. 9C. Assuming that VTR2, which is the product category-number of the node # 2 having a smaller node address than itself, is valid, and that VTR1 is assigned to the node # 1 having a smaller node address than itself, VTR3 is assigned to itself. Allocate. As a result, the product category-specific numbers shown in FIG. 8B are assigned in any case.

FIG. 1 is a flowchart of the procedure described above.
0 to 13 are shown. 10 and 11 show the procedure for determining the logical address of the own node.
Is a procedure for determining the logical address of another node.

[4] Control of Device Based on Logical Address Next, an example of controlling the device in the system based on the logical address thus determined will be described. In the communication system shown in FIG. 14A, consider a case where VTR2 is removed from the system while editing control is being performed using CONT1 as an AV controller, VTR1 as a player and VTR3 as a recorder.

First, when editing is started in the state of FIG. 14A, the packets transmitted by the AV controller to VTR1 and VTR3 are those shown in FIGS. 15A and 15B, respectively. When the VTR 2 is removed from the bus during editing, the bus is reset and node IDs are assigned as shown in FIG. 14 (b). As a result, V
Although the node ID of TR3 changes, the logical address does not change, as is clear from the above description.
The editing operation is not affected as long as the correspondence with the node ID is checked. Packets for ending the editing and stopping the player and the recorder are as shown in FIGS. 15 (c) and 15 (d). The same operation can be performed when the editing is started in the state of FIG. 14B and the VTR 2 is connected to the bus during the editing to bring the state of FIG. 14A.

In this way, the logical address does not change even if the terminal device of the system is removed and inserted. Further, the same logical address is assigned no matter how many times the device is removed and inserted.

[0044]

As described in detail above, the present invention has the following effects. (1) When the communication system is reset, the original logical address, for example, the product category number can be automatically assigned.

(2) Each node can grasp how many nodes with what logical address are connected to the communication system. (3) Even if a physical address is changed by removing and inserting a certain node in the system and resetting it, the logical addresses of other nodes do not change.

(4) In the removal / insertion of one node, the same logical address is assigned to that node each time it is inserted. (5) By controlling the nodes in the system based on the logical address, even if the node at the end of the network that is not the control target is removed or inserted, the control operation is not affected.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a basic configuration of a communication device serving as a node in the present invention.

FIG. 2 is a diagram showing an example of a packet configuration in a digital I / F of the present invention.

FIG. 3 is a diagram showing an example of a communication system to which the present invention is applied.

4 is a diagram showing an example of contents of an address table in the communication system of FIG.

5 is a diagram showing an example of a packet used in the communication system of FIG.

6 is a node ID of # 1 in the communication system of FIG. 3;
It is a figure which shows an example of the content of the address table in this node.

7 is a node ID # 2 in the communication system of FIG. 3;
It is a figure which shows an example of the content of the address table in this node.

FIG. 8 is a diagram showing another example of a communication system to which the present invention has been applied.

9 is a diagram showing an example of contents of an address table in the communication system of FIG.

FIG. 10 is a flowchart showing a part of the procedure for determining the logical address of the own node in the present invention.

FIG. 11 is a flowchart showing the remaining part of the procedure for determining the logical address of the own node in the present invention.

FIG. 12 is a flowchart showing a part of a procedure for deciding a logical address of another node in the present invention.

FIG. 13 is a flowchart showing the remaining part of the procedure for determining the logical address of another node in the present invention.

FIG. 14 is a diagram showing an example of a communication system for controlling devices in the system based on a logical address of the present invention.

15 is a diagram showing an example of commands used in the communication system of FIG.

FIG. 16 is a diagram showing an example of a communication system for transmitting and receiving digital video signals and the like between AV devices and the like connected to a bus.

17 is a diagram equivalently describing the communication system of FIG.

18 is a diagram showing an example of a communication cycle in the communication system of FIG.

[Explanation of symbols]

3 ... Digital I / F, 5 ... Microcomputer, 6 ... Address table, 7 ... Addressing program,

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[Procedure amendment]

[Submission date] May 13, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Title of invention

[Correction method] Change

[Correction content]

Title: Communication system and communication device used therefor

Claims (2)

[Claims] 1. A communication system configured such that a physical address is automatically assigned to each node according to a connection state between the nodes, and each node is provided with means for storing a logical address of itself and other nodes. A communication system characterized by the above. 2. A communication device used in a communication system configured so that a physical address is automatically assigned to each node according to a connection state between the nodes, and means for storing logical addresses of itself and other nodes is provided. A communication device characterized by being provided.