JP2001077839A - Serial bus network system and serial bus network method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a serial bus network system and a serial bus network method where loop connection is automatically release and a normal topology can be generated. SOLUTION: In a network consisting of a plurality of nodes, each node is provided with a 1394 input output port 11 connected to a 1394 cable and a 1394 circuit (physical layer) 12 that processes an electric signal sent from the 1394 output port 11 or to be sent to the 1394 output port 11, a port switch 13 that switches the 1394 input output port 11 is provided between the 1394 input output port 11 and the 1394 circuit 12, and a control section 14 controls the switching of the port switch 13. The control section 14 opens the port switch 13 on the basis of a loop event that is issued when a master/slave relation of nodes is not decided within a prescribed time from bus reset to automatically release the loop connection in existence in the network.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a serial bus network device, and more particularly, to a network using an IEEE 1394 serial bus, which automatically cancels a loop connection unnecessary for forming a topology when power is turned on, etc. The present invention relates to a serial bus network device and a serial bus network method that can automatically perform a topology connection.

[0002]

2. Description of the Related Art A parallel interface SCSI (Small) connecting a computer and peripheral devices, which has been the mainstream in the past, has been developed.
IEEE 1394 high-speed serial bus (IEEE is the Institute of Electrical and Electronics Engineers: The Institute of Electronics)
(Abbreviation of Electrical and Electronics Engineers, Inc., hereinafter referred to as IEEE 1394 or simply 1394)
Is attracting attention.

Prior to the formal standard, IEEE1394 was called P1394, and Nikkei Electronics 199
The details are described on pages 152 to 163 of the article (Reference 1) of 4.7.4 (No. 612), “Exploring post-SCSI design concept, comparing three new interfaces”. As described on page 161 and subsequent pages of the article, P1394 is based on computers,
"Isochronous for multimedia
It has a transfer function ", and is therefore more effective for image data than other interface methods. In other words, video and audio data must be
Every 5 μs), there is no jerkyness even if it is transferred and reproduced.

[0004] Further, P1394 has a function of automatically setting a topology (refer to page 155 of Reference 1).
(See “Automatic topology configuration” on page 159.) P1
Reference numeral 394 re-sets the connection relationship of each device, sets the parent-child relationship between devices, and sets the ID of each device when the devices are connected, disconnected, or powered on. That is, SCS
I's only Dizzy Chain topology, but P139
Numeral 4 also enables a tree structure and can connect a plurality of devices.

[0005] By the way, US Pat. 5,394,5
56 (Apple Computer, Inc.) “Method and Apparatu
s for unique address assignment, node self-identif
ication and topology mapping for a directed acycli
c graph (method and apparatus for performing unique address assignment, node identification, and topology formation for acyclic command charts) ”(reference 2) forms the network topology at the thirteenth stage. In this case, a solution in the case where a loop connection exists is described.

That is, when forming a network topology, if a predetermined time-out period has elapsed since the time of bus initialization (bus reset),
There is a loop connection in the network and the user is notified by an output device which nodes are included in the loop connection. The user attempts to solve the problem by manually releasing the link in the loop connection (that is, disconnecting the connection cable in the loop connection).

[0007] However, in the method according to the above-mentioned document 2, the user is notified of the node forming the loop and the user cancels the loop connection. However, the loop connection must be removed depending on the installation location of the device. Since the operation of disconnecting the cable is complicated and the user's knowledge level of the device is various, an accurate process is not always performed. For example, there is a possibility that a cable that does not form a loop is accidentally deleted.

[0008]

As described above, in the prior art, since the method is such that the user is notified of the release of the loop connection and the release is performed, an accurate process is not always performed.

In view of the above, the present invention has been made in view of the above problems, and has a serial bus network device and a serial bus network device capable of automatically canceling a loop connection without depending on a user and forming a normal topology. It is an object to provide a bus network method.

[0010]

According to the present invention, in a serial bus network device in a network formed by a plurality of nodes, the node determines a parent-child relationship of the nodes within a time limit from the start of a bus reset.
Means for issuing a loop event indicating the presence of a loop connection when the determination of the parent-child relationship of the node is not made within the time limit from the start of the bus reset, and means for releasing the loop connection based on the issuance of the loop event; It is provided with.

Specifically, the canceling means determines that the node which has issued the loop event has (N is an integer of 2 or more) ports of its own node involved in the loop connection. -1) The ports are forcibly opened by the switch means and the loop connection is automatically released.

According to the present invention, in a network formed by a plurality of nodes, the parent-child relationship of the nodes is determined within the time limit from the start of the bus reset, and the parent-child relationship of the nodes is not determined within the time limit. In this case, a loop event can be issued, and the loop connection can be automatically released based on the issuance. Therefore, it is not necessary for the user to release the loop connection by himself, and even when a new device (node) is connected to the network and a loop exists, the loop is automatically released and the normal topology is promptly restored. Connection can be realized.

[0013]

Embodiments of the present invention will be described with reference to the drawings. 1 to 10 illustrate a serial bus network device according to an embodiment of the present invention. Before describing the embodiments of the present invention, first, FIGS.
Referring to FIG. 14, a method of determining a tree configuration, which is a general network topology connection, will be described.
This is based on Reference 2 shown above). In addition, IEEE
In 1394, the topology (connection form) can be a daisy chain or a tree structure by branch connection, and management is performed by node ID.

As shown in FIG. 12, first, nodes C (3), D (4), and E (5) called "leaves" having only one port are connected to each other. A (1) and B (2) are notified of their parent (Parent Notify). Nodes A (1) and B (2) receiving the notification become parents, and notify nodes C (3), D (4) and E (5) that sent the notification that they are children (Child). Notify). Now node A
(1) and node C (3), node B (2) and node D
(4) The parent-child relationship between the node B (2) and the node E (5) is determined.

Next, as shown in FIG. 13, Parent Notify is performed on node A (1) from node B (2) for which the parent-child relationship has not yet been determined, and node A (1) receiving this performs The child Notify is returned to the node B (2), and the relationship that the node A (1) is a parent and the node B (2) is a child is determined (the reverse is also possible).

When the parent-child relationship of all the nodes is determined in this way, as shown in FIG.
(1) Node IDs are assigned in order from the leaf (that is, node C (3)) of a port (that is, port 1) having a smaller port number (that is, a root node) (that is, port 1). Here, a node connected to two or more devices is referred to as a branch. A node D (4) which is a leaf of port 1 of the node B (2) which is a branch has a node ID = 1.
Is assigned to the node E (5) which is a leaf of the port 2 of the node B (2), and the node ID = 2 is assigned to the node E (5) which is a branch of the port 2 of the root node A (1). Is assigned node ID = 3, and finally the root node A
Node ID = 4 is assigned to (1). In this way,
The tree structure of the network is determined.

Here, if two devices A and B having two or more ports are connected by two cables as shown in FIG. 4A, a loop connection will result. Both devices A and B are no longer leaves. In the prior art document 2 described above, a loop event (a signal indicating the presence of a loop connection) is issued after a preset time limit (called a timeout time) to notify the user of the loop connection. You.

In accordance with the notification, the user checks the network and manually opens the loop connection to solve the problem.

On the other hand, in the serial bus network device according to the embodiment of the present invention shown in FIG. 1, the LSI (12), which is the 1394 physical layer, and the 1394 input / output port (11)
And a port switch (13) is introduced between them to automatically release the loop according to the flowchart shown in FIG. That is, when the 1394 cable connected to the 1394 input / output port (11) is involved in the loop connection of the network, the loop connection can be disconnected by the input / output port opening / closing port switch (13).

The embodiment will be described in more detail.

In FIG. 1, a device (10), which is a node, is connected to an external cable (hereinafter referred to as a 1394 cable) defined by the IEEE 1394 standard.
394 input / output port (11) and 1394 input / output port (11), or 1394 input / output port (11)
1394L that constitutes a physical layer that processes electrical signals sent to
SI (12), 1394 input / output port (11) and 1394
A port switch (13) that opens and closes a port and a control unit (14) that controls opening and closing of the port switch (13) are provided between the LSIs (12) (a 1394 LSI).
(12) is configured to further connect a circuit such as a data link layer, but other functional blocks other than the above are omitted.)

When there are a plurality of 1394 input / output ports (11), the port switches (13) and the control units (14) are provided by the corresponding numbers.

FIG. 2 shows an example of the configuration when there are a plurality of 1394 input / output ports. For 1394 LSIs, one LSI often has about three input / output ports. Therefore, as the number of LSIs, the quotient obtained by dividing the number of 1394 input / output ports of the device by the number of 1394 LSI input / output ports is rounded up to an integer. You just need to get the number. For example, FIG.
As shown in (1), when the number of 1394 input / output ports of the device (101) is 5 and the number of input / output ports of one 1394 LSI is 3, two 1394 LSIs (121, 122) are required.

In the device (101) of FIG.
It has input / output ports (111, 112, 113, 114, 115) and two 1394 LSIs (121, 122).
Each of the LSIs (121, 122) has three input / output ports (P11, P12, P13) and (P21, P22, P23).

The 1394 input / output ports (111, 11
2, 113, 114, 115) and the 1394 LSI input / output ports (P11, P12, P13, P21, P22) are provided on the respective lines, and the 1394 input / output ports (111, 112, 113, 114, 11)
5) Port switches for opening and closing (131, 132, 133,
134, 135) are arranged, and the opening and closing of each port switch is controlled by the control unit (141, 142, 143, 144, 145). In FIG. 2, the input / output port P2 of the LSI (122) is used.
3 is an empty terminal.

Although the port switch is installed outside the 1394 LSI in FIGS. 1 and 2, it may be configured inside the LSI.

FIG. 3 shows a flow of determining the tree structure of the network. This decision flow is 1394
This is executed by a controller circuit of an LSI (physical layer).

When a device is newly connected to the network or a connected device in a power-off state is turned on, a bus reset (S301), which is a bus initialization, is started. The timer starts (S302) immediately after the bus reset (S301), and in the case of a normal network without a loop connection, the elapsed time T after the bus reset is less than or equal to a preset time limit T1 (T ≦ T1). When the parent-child relationship determination process (S306) is performed and the parent-child relationship of all nodes is determined (S307), a node ID is assigned to each node by the root node (S308), and a series of initialization processes ends.

Next, a case where the network has a loop connection will be described. First, FIGS. 4 (a), 5 (a) and 6 (a)
When the whole is in a loop connection as in (1), the timer exceeds the time limit T1 in the first step (T>
T1) (S303), the network issues a loop event indicating the presence of a loop connection (S304). The timing at which this loop event is issued is a time after the time limit T1 and is arbitrarily set at each node. FIG.
FIGS. 5A, 5A and 6A show a case where the node A first issues this loop event. Thereafter, as shown in FIGS. 4 (a), 5 (a) and 6 (a), the node A which first issued the loop event (indicated by hatching in each figure) is connected to its own node. Out of the N number of ports, any (N-1) ports are opened by the port switch (13) to release the loop (S305).
That is, in FIGS. 4 and 6, one of the two ports is released (ports indicated by broken lines are opened in FIGS. 4B and 6B), and in FIG. 5, N ports (N -1) ports are released. After all, (N-1) ports out of N (N is an integer of 2 or more) ports need only be released.

When K nodes are connected in a loop, any one of the nodes only needs to release one of the two ports. 7A and 7B, the node A releases one port. Processing after loop connection is released (decision of parent-child relationship of nodes, assignment of node ID)
Are the same as those described above (S306 to S308), and will not be described.

Next, a case where a loop connection is partially provided is as follows.
This will be described with reference to the example of FIG. The timer starts (S302) immediately after the bus reset (S301), but before the time limit T1 (T ≦
T1) shows the parent-child relationship between node A and node C (indicated by circled number 1), and the parent-child relationship between node B and node A (circled numeral 2).
) Is determined. Since the relationship between the remaining nodes B, D, and E is a lube connection, the parent-child relationship is not determined.

Therefore, the timer starts from the time when the parent-child relationship (indicated by the circled number 2) is determined, and when the time exceeds the time limit T1 (T> T1), any one of the three nodes B, D, and E (FIG. In FIG. 8 (a), the node D) first issues a loop event and releases one of the two ports connected to itself. As a result, the loop is released as shown in FIG. 8B, and the parent-child relationship between the node B and the node D (indicated by a circle 3) and the parent-child relationship between the node B and the node E (indicated by a circle 4) are determined. Thereafter, each node ID is assigned by the root node B, and the tree structure is determined.

Next, the case of a multiplexed loop-connected network will be described with reference to two examples shown in FIGS. Also in this case, the loop connection can be released by performing the processing according to the algorithm of FIG. 9 and 10,
There are two loops in each network.

In FIG. 9, the timer starts (S302) immediately after the bus reset (S301), but before the time limit T1 (T ≦ T1), the parent-child relationship between the nodes C and G (indicated by a circle 1) is determined. I do. The relationship between the remaining nodes A, B, E, F, and C is a loop connection, and the relationship between the nodes B, D, and E is also a loop connection (further, the nodes A, B, and N). D, node E, node F, and node C are also in a loop connection), so that the parent-child relationship is not determined.

Accordingly, the timer starts when the parent-child relationship (indicated by the circled number 1) is determined, and when the time exceeds the time limit T1 (T> T1), the six nodes A, B, C, D,
Any one of E and F (node D in FIG. 9A) issues a loop event first, and releases one of the two ports connected to itself. As a result, the loop is released, and the parent-child relationship between the nodes E and D (indicated by a circle 2) is determined. The remaining nodes A, B, E,
Since the relationship between the nodes F and C is a loop connection, the parent-child relationship is not determined.

Accordingly, when the parent-child relationship (indicated by the circled number 2) is determined, the timer starts, and when the time limit T1 is exceeded (T> T1), the five nodes A, B, C, E,
Any of F (node F in FIG. 9B) first issues a loop event and releases one of the two ports connected to itself. As a result, the loop is released as shown in FIG. 9C, and the parent-child relationship between the nodes E and F (shown by a circle 3), the parent-child relationship between the nodes A and C (shown by a circle 4), and the node B The parent-child relationship of node A (indicated by a circled number 5) and the parent-child relationship of node E and node B (indicated by a circled number 6) are determined. Thereafter, each node ID is assigned by the root node E, and the tree structure is determined.

In FIG. 10, the bus reset (S301)
Immediately after the start (S302), the node A,
Since the relationship between the nodes B, C, D, and E is a loop connection, and the relationship between the nodes D, F, and G is also a loop connection, the parent-child relationship is not determined.

Exceeding the time limit T1 of the timer (T> T
1) and any one of these seven nodes A, B, C, D, E, F, and G (node E in FIG. 10A) first issues a loop event and is connected to itself. One of the two ports is opened. This breaks the loop,
The parent-child relationship between node D and node E (indicated by a circle numeral 1) is determined, the parent-child relationship between node B and node A (indicated by circle numeral 2) is determined, and the parent-child relationship between node C and node B (indicated by circle numeral 3). ) Is determined, and the parent-child relationship between the nodes D and C (indicated by a circle 4) is determined. Since the relationship between the remaining nodes D, F, and G is a loop connection, the parent-child relationship is not determined.

Accordingly, when the parent-child relationship (indicated by the circled number 4) is determined, the timer starts, and when the time exceeds the time limit T1 (T> T1), one of the three nodes D, F, and G (FIG. In 10 (b), the node G) first issues a loop event and releases one of the two ports connected to itself. As a result, the loop is released as shown in FIG. 10C, and the parent-child relationship between the node F and the node G (indicated by a circle numeral 5) and the parent-child relationship between the node D and the node F (indicated by a circle numeral 6) are determined. Thereafter, each node ID is assigned by the root node D, and the tree structure is determined.

FIG. 11 shows a serial bus network device according to another embodiment of the present invention. The difference between this embodiment and the embodiment of FIG. 1 is that the input / output port (11) of the device (10) constituting the node and the 1394 LSI
(12) A display unit (15) for indicating whether the port switch (13) provided therebetween is closed (on) or open (off). The display section (15) is controlled by a control section (14) to turn on and off the display section (15), and is arranged so that display light can be confirmed by a user from outside the device (10).

With such a configuration, when the port switch (11) is closed, the display unit (15) composed of an LED or the like is turned on by the control unit (14), and the user operates the 1394 LSI in the device (10). It can be seen that (12) is electrically connected to the 1394 cable. Also,
When the port switch (13) is open, the display (15) turns off, and the user operates the 1394L in the device (10).
It can be known that the SI (12) is electrically disconnected from the 1394 cable.

As described above, the display unit (15) is turned on and off in response to turning on and off of the input / output port opening / closing port switch (13).
Whether the 394 cable is involved in the tree structure of the network can be easily determined, and unnecessary cables not involved in the tree structure can be removed.

When there are a plurality of 1394 input / output ports (11), the port switches (13) and the control units (14) are provided by the corresponding numbers as shown in FIG. ) Are provided in the same number as the control units (14) corresponding to the control units (14).

In the embodiment described above, the tree structure is mainly described as the network form (topology). However, the present invention can be applied to a daisy chain as shown in FIG. 7B.

[0045]

As described above, according to the present invention, a loop connection in a network can be automatically released without bothering the user. Since the normal topology connection is automatically performed, there is an advantage that the network can be quickly formed without error.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a serial bus network device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a serial bus network device having a plurality of 1394 input / output ports.

FIG. 3 is a flowchart showing a network topology formation (tree configuration) flow by the apparatus of FIG. 1;

FIG. 4 is a diagram illustrating loop release in a two-unit network.

FIG. 5 is a diagram illustrating loop release in a two-unit network.

FIG. 6 is a diagram for explaining loop release in a three-unit network.

FIG. 7 is a view for explaining loop release when K nodes are connected in a loop.

FIG. 8 is a diagram for explaining local loop release in a multi-unit network.

FIG. 9 is a diagram for explaining multiplex loop release in a multi-unit network.

FIG. 10 is a view for explaining another example of canceling a multiple loop in a multi-unit network.

FIG. 11 is a block diagram showing a serial bus network device according to another embodiment of the present invention.

FIG. 12 is a view for explaining a method of determining a tree structure of a general network (node identification method).

FIG. 13 is a view for explaining a method of determining a tree structure of a general network (node identification method).

FIG. 14 is a view for explaining a general network tree structure determination method (node identification method).

[Explanation of symbols]

10: device (node), 11: 1394 input / output port,
12 ... 1394 LSI (physical layer), 13 ... Port switch, 14 ... Control unit.

Claims (6)

[Claims] A 1394 input / output port connected to a 1394 cable;
A physical layer that processes an electric signal to be sent to the 94 input / output port; a port switch that is connected to the 1394 input / output port to open and close the input / output port; and a control unit that controls opening and closing of the port switch. A serial bus network device comprising: 2. The serial bus network device according to claim 1, further comprising a display unit for displaying whether the 1394 input / output port is open or closed. 3. A serial bus network device in a network formed by a plurality of nodes, wherein the node determines a parent-child relationship of the nodes within a time limit from the start of the bus reset; Means for issuing a loop event indicating the existence of a loop connection when the determination of the parent-child relationship of the node is not performed; and means for releasing the loop connection based on the issuance of the loop event. Serial bus network device. 4. The means for releasing a loop connection comprises: a node which has issued a loop event, wherein (N is an integer of 2 or more) ports of its own node involved in the loop connection; 4. The serial bus network device according to claim 3, wherein: (1) ports are opened by switch means to release the loop connection. 5. A serial bus network method in a network formed by a plurality of nodes, the node determining a parent-child relationship of the nodes within a time limit from the start of the bus reset, and a time limit from the start of the bus reset. Issuing a loop event indicating the presence of a loop connection when the parent-child relationship of the node is not determined within the node, and releasing the loop connection based on the issuance of the loop event. And the serial bus network method. 6. When a plurality of nodes are multiplexly connected in a loop, the node determines the parent-child relationship, issues the loop event, and releases the loop connection. 6. The serial bus network method according to claim 5, wherein the network is formed by performing the steps a plurality of times.