JP2850605B2 - Transmission method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a mechanism for improving the use efficiency of a slot, which is a transmission switching unit of a bus type local area network, for example.

[0002]

2. Description of the Related Art FIG. 12 shows The New Slot Reutilization Scheme published in the September issue of IEICE Transactions E
This is the network configuration of the bus-type local area network shown in e in DQDB MAN. In the figure, 1 is a transmission line, 2 is a slot generator, 3 is a slot terminator, and 4 is a node for performing communication.

FIG. 13 shows a transmission path 1a of the node 4 shown in FIG.
FIG. 2 is a diagram showing a configuration of a part for transmitting a slot to a. 5
Is a reception processing function for processing a slot received from the transmission path, 6 is a transmission processing function for transmitting a slot to the transmission path, 7 is a slot erasing function for reusing a used slot, and 8 is a slot erasing function. Shows a switch that selects whether to use the function.

FIG. 14 shows the internal configuration of the slot erase function 8 of FIG. In the figure, reference numeral 9 denotes a slot releasing unit for reproducing used slots, 10 a slot separating unit for separating slots according to their types, 11 a slot multiplexing unit for multiplexing the separated slots, and 12 a transmission line by the slot releasing unit 9. With the release of the slot on 1a, a state machine that controls to cancel the transmission reservation of the slot performed using the slot on the transmission path 1b, 13 is a buffer that stores slots and applies a fixed delay, and 14 is a transmission buffer. A slot reception detecting unit for detecting reception of a slot from the path 1b, a reservation canceling unit 15 for canceling a transmission reservation on the transmission path 1b, and a control signal line 16 between the above units.

FIG. 15 shows a format of a slot which is a transmission exchange unit. In the figure, reference numeral 17 denotes the entire slot. Payload indicates the information actually transmitted,
Other areas indicate the header of the slot.

Next, the operation will be described. The transmission and reception of the slots is as indicated in the draft standard in Working Group 802.6 of the Local Area Network Standards Organization of the Institute of Electrical and Electronics Engineers (IEEE).
As shown in FIG. 12, the network has a double transmission path, and the transmission directions 100 are opposite to each other. In the slot generator 2 and the slot terminator 3 located at both ends of the bus, fixed-length slots 17 as transmission units flowing on the transmission path are generated and terminated.

The slots shown in FIG. 15 are divided into those for data communication and those for isochronous communication. The proportion of these slots is the same for the two transmission paths. They are identified by the Slot Type bit. For the isochronous slot, a node that can be used in the slot generator 2 is determined in advance, and only the determined node can be used.

The data communication slot is transmitted by the transmission processing function 6 shown in FIG. 13 as follows. When a slot to be transmitted occurs, transmission is reserved by making one of the REQUEST bits of the data flowing on the transmission path opposite to the transmission direction significant. Each node (each station) 4 that transmits data decodes the REQUEST bit of the slot flowing through the transmission path on the opposite side and recognizes the reservation state in the upstream station upstream from the own station. Also, the BUSY bit of the slot flowing in the transmission path in the direction of transmission is decoded to recognize the empty state of the slot. The slot allocated to the own station is detected from the number of REQUEST bits and the number of BUSY bits of the received slot, data to be transmitted is placed on the Payload of the slot, and the BUSY bit of the slot is set to 1 and transmitted to the transmission path. .

Regarding the reception of a slot, the reception processing function 5
, Regardless of whether it is for data communication or isochronous,
Decode the VCI area of the slot flowing through the transmission path,
If the slot is addressed to the own node, the slot is copied inside the node. If the received slot is a slot for data communication addressed to the own node, 1 is written to the PSR bit of the next slot to be received from the same direction. If it is not addressed to the own node, copying to the inside of the node is not performed.

When the slot erase function 7 is used by the switch 8 in FIG. 13, the following operation is further added. The switch on / off is determined in advance for each node before operating the network.

The operation of the slot erase function will be described with reference to FIG. The slots received from the transmission path 1a are accumulated in the slot release unit for the time required to transmit one slot (hereinafter referred to as slot time), and the PSR bits of the slots received from the same direction are decoded next. If the PSR bit is 1, the stored slot is released by setting the BUSY bit to 0. The released slot can be reused at a downstream node thereafter. The release point is notified to the state machine 12. Thereafter, the isochronous slot and the data communication slot are separated by the slot separating unit 10 and multiplexed by the slot multiplexing unit 11. During this time, the slot for data communication is buffered by the buffer 13 and a fixed delay of N slot times, which is a part of the time for canceling the reservation described later, is applied. The multiplexing in the slot multiplexing unit 11 inserts a data communication slot into a space between received isochronous slots. Thus, the isochronous slot does not cause a delay in the slot multiplexing section,
Since the data communication slot waits until a space between the isochronous slots is found, a delay may occur.

On the other hand, reception of the slot received from the transmission line 1b is detected by the slot reception detecting section 14 and is notified to the state machine 12. Thereafter, the slot separation unit 10
, And is separated into an isochronous slot and a data communication slot. During this time, a fixed delay of one slot time is applied in the buffer 13 for the isochronous slot. The data communication slot is subjected to a fixed delay of N + 1 slots in the buffer 13, and the reservation canceling unit 15 sets the REQUEST bit to 0 by the control signal from the state machine 12 indicating that the slot has been released. The transmission reservation made is canceled, and the state machine 12 is notified when the reservation is canceled. That is, the slot release unit 9 releases the slot and
When the released slot is transmitted to the downstream station of a, the reservation canceling unit 15 cancels the reservation of the bus 1b from the upstream station. By having such a function in the node, the slot can be reused, and the slot can be effectively used.

When the state machine 12 receives a signal indicating the slot release from the slot release unit 9, it measures time in slot time units based on the signal from the slot reception detection unit 14. Then, within a certain period of time (for example, M slot time as described later) from the time of slot release, the reservation cancellation unit 15 is given permission to cancel the reservation of the slot. Then, if the M slot time has elapsed or if a notice of reservation cancellation is received from the reservation cancellation unit 15, the issuance of the permission is canceled.

In the above operation, how to determine the M slot time becomes a problem. This is because one slot time is added to twice the time required to reach the adjacent downstream node from the time when the data communication slot is released. Time or less. Therefore, M
The slot time depends on the fixed delay N slot time. In other words, if the fixed delay increases, the M slot time also increases, the time required for permission for canceling the reservation increases, and the probability of canceling the reservation increases.

[0015]

The slot erasing function in the node of the conventional bus type local area network operates as described above. Therefore, when the ratio of data communication slot allocation is smaller than that of isochronous slots, and when the number of data communication slots transmitted is small, the delay time caused by passing the slot erasure function is There is a problem that the delay time becomes dominant. Further, there is a problem that a delay is required when passing through the slot erasing function even for an isochronous slot in which the slot is not reused.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and dynamically switches the use of the slot erasure function in a node and reduces the passage delay amount of the slot in the slot erasure function. It is intended to reduce.

[0017]

In the bus type local area network according to the first aspect of the present invention, the slot erasing function in each node is dynamically used or used depending on the use state such as the ratio of data communication slots. And has the following elements. (A) first and second buses for transmitting information in predetermined transmission units in opposite directions ; and (b) a monitor for monitoring a use state of the information of the transmission unit at a terminating end of the first bus. (C) information generating means for generating control information for controlling the use of the transmission unit based on the monitoring result of the monitoring means and transmitting the control information to a second bus; (d) the first and second information processing means is connected to the bus, receives the control information from the second bus, based on its contents, said first
And a node for changing the use state of the transmission unit of the second bus .

Further, in the second invention, in the state machine in the slot erasing function, the fixed time is not fixed at the time when the released slot is transmitted to the downstream node but at the time when the slot is released to the downstream node. The reservation cancellation permission is given from the transmission line on the opposite side, and has the following elements. (A) a bus for transmitting information in a predetermined transmission unit; (b) a use node that reserves use of the transmission unit and uses the transmission unit;
(C) determining the end of use of the transmission unit used by the use node, enabling the transmission unit to be reused and transmitting the transmission unit to the bus, and starting from the time of transmitting the reusable transmission unit to the bus. A reuse node that cancels a reservation of a transmission unit reserved by the use node for a predetermined time.

In the third invention, the delay amount of the buffer for generating the fixed delay of the slot at the preceding stage is considered in consideration of the delay time of the data communication slot generated in the slot multiplexing unit in the slot erasing function. Is variable, and the transmission unit in which the node is transmitted to the first bus
Received the information of the first bus, with a predetermined delay, and again on the first bus
A delay unit for transmitting the information, and the information generation unit.
The delay based on the control information transmitted to the second bus.
That there is a changing means for changing the magnitude of the delay of the means.
Features.

Further, in the fourth invention, the isochronous slot (an example of the first type of transmission unit) is separated at the entrance of the slot erasure function, and the processing in the slot erasure function is performed in the data communication slot (the second type of transmission unit). It is only an example of a transmission unit) and has the following elements.
(A) a bus for transmitting information in a first type and a second type of transmission unit; (b) a first type of transmission unit and a second type of transmission unit connected to the bus and separated from the bus; Separating means for transmitting the first type of transmission unit as it is to the bus, storing the second type of transmission unit separated by the separating means, and storing the stored first-order transmission unit based on the content of the second-type transmission unit which arrives later. And processing means for determining the processing of the second type of transmission unit.

[0021]

In the first aspect of the present invention, the slot erasing function is switched when the ratio of the data communication slots is small, for example, by switching the slot erasing function after monitoring the use state of the slot by the monitoring means. Since it is not used, there is no delay that occurs when passing the function.

In the second invention, in the state machine in the slot erasing function, the released slot is not set at the time when the slot is released, but at a certain time from the time when the slot is transmitted to the downstream node. Since the cancellation of the reservation is given from the transmission path on the side, the permitted time for the cancellation of the reservation is increased, and the slot can be used efficiently.

In the third invention, the delay of a buffer for generating a fixed delay of the preceding slot is considered in consideration of the delay time of the data communication slot generated in the slot multiplexing section in the slot erasing function. Since the amount is variable, the delay amount of the buffer can be adjusted in accordance with the delay time in the slot multiplexing unit, and the delay times of the two can be made equal.

In the fourth aspect, the isochronous slot is separated at the entrance of the slot erasing function, and the processing in the slot erasing function is performed only for the data communication slot. Therefore, the delay of the isochronous slot is eliminated.

[0025]

【Example】

Embodiment 1 FIG. An embodiment of the first invention will be described below. FIG. 1 is a configuration example of a bus-type network to which a monitor device for a slot on a transmission line is attached. 2 in the figure
0 is a monitor device, 21 is an information generation unit that generates information for controlling use of the slot erase device function, 22
Indicates a communication path of control information.

Next, the operation will be described. A description will be given of a case related to the transmission line 1a as in the conventional example. In the monitor device 20a, the Sl of the slot received from the transmission path 1b is
The ottype bit and the REQUEST bit are decoded to monitor a significant number in a certain time (for example, one second). The total number of data communication slots reserved for transmission by each node with respect to the transmission path 1a can be determined from the significant number of REQUEST bits. Further, since the ratio of the isochronous slot to the data communication slot is the same in the two transmission paths, the ratio of the isochronous slot in the transmission path 1a can be determined from the significant number of Slot type bits.

Based on the above information, the information generation unit 21 generates instruction information for using or canceling the use of the slot erasure function 7 for the transmission path 1a, and notifies the slot generator 2. The slot generator 2 broadcasts to each node a control slot in which the used node information on the node using the slot erasing function 7 or the node whose use is to be discontinued is written in the payload as a data communication slot with the BUSY bit set to 1. . In each node, it is determined whether to use the slot erasure function 7 or stop using it according to the used node information carried by the slot. This operation also operates simultaneously with the slot erasing function for another transmission line 1b.

As for the use of the slot erasure function 7, the transmission path 1a and the transmission path 1b must be the same.
For this purpose, the monitoring device 20a also monitors the control slot that controls the use of the slot erasure function 7 for the transmission line 1b, and the information generation unit 21a takes into account the information to control the use of the slot erasure function 7. Generate

Next, a flow for controlling the use of the slot erasing function in the information generating unit 21a in the first embodiment will be described with reference to FIG. First, step 30b
To obtain the node information of the slot erasure function using the control slot received from the opposite transmission line,
In step c, which node on the network uses the slot erase function is determined. Further, in step 31d, the number of slots for data communication at fixed time intervals of slots received from the transmission path on the opposite side and the number of reservations among them are calculated, that is, the number of slots in which the REQUEST bit is 1. An operation is performed in step 30e based on the result. Then, in steps 30f and 30h, it is determined whether the slot erasure function is increased or decreased. as a result,
The increase processing and the decrease processing in steps 30g and 30i are performed, and in step 30j, the current use state information of the slot erase function is updated.

Next, the contents of steps 30e, 30f and 30h will be described with reference to FIG. The number x of data communication slots is compared with a1 and a2 which are set in advance. Further, the reservation number y is compared with b1 and b2 set in advance. Based on the result shown in the table shown in FIG. 3, it is determined whether the number of nodes using the slot erase function should be increased or decreased. For example, when a slot x for data communication is received within a certain time period a2 or more, and the number of reservations y in that slot is between b1 and b2, the number of nodes using the slot erasure function is increased.

Next, referring to FIG. 4, the process of increasing and decreasing the number of nodes using the slot erase function in steps 30g and 30i is performed. Regarding the increase processing, the interval between nodes using the slot erase function is checked in step 31b, and the maximum interval is detected in step 31c. Then, in step 31d, it is decided to use the slot erasing function of the middle node at the maximum point. On the other hand, in the reduction process, the interval between the used nodes is checked in step 32b. In step 32c, the sum of two consecutive intervals is calculated. In step 32d, a location where the sum is minimum is checked. In step 32e, the node using the slot erasure function corresponding to the center of the location where the sum becomes minimum cancels the use of the function.

Next, the slot erasing function 7 using the switch 8 shown in FIG. 13 when each node is instructed to use and cancel the use of the slot erasing function with reference to FIG.
A method for switching the mode will be described. FIG. 5 is a diagram showing the vicinity of the switch 8 of one node 4 shown in FIG. 1 in detail. In FIG. 5, reference numeral 23 denotes a FIFO memory for timing correction when the slot erase function 7 is not used.
It is assumed that the capacity is equal to or larger than the delay amount generated by the slot erase function 7. 24 is a control circuit for controlling writing and reading of the FIFO 23, 25 is an insertion circuit for forcibly inserting an empty slot, that is, a slot in which the BUSY bit and the REQUEST bit are 0, and 26 is a circuit for using the slot erasing function. 5 shows a comparison circuit for comparing a slot coming from a path 51 with a slot coming from a path 52 when not used.

The switching operation will be described below.
First, an operation for switching from a state in which the slot erase function is used to a state in which the slot erase function is not used will be described.
In this case, as shown in FIG. 13, the same slot is output to the switch 8 earlier in time when the same slot is not used than when the same slot is not used. For this reason, the comparison circuit 26 of FIG. 5 operates until the contents other than the first byte of the slot output from the slot erase function 7 and the slot output from the FIFO 23 match.
FIFO control circuit 2 so as not to read the slot from
Notify 4. At the same time, the FIFO 23 is informed that the empty slot among the received data communication slots is only ignored, and is not written. Then, at the time of coincidence, reading from the FIFO 23 is started, and at the same time, the switch 8 is switched to the side where the slot erase function 7 is not used. If there are no more slots stored in the FIFO 23, the writing to the FIFO 23 is not restricted.

With the above operation, the capacity of the FIFO 23 becomes 0 after a sufficient time has elapsed, and the operation is performed when the slot erase function 7 is not used without losing the slot.

Next, the operation for switching from the state where the slot erase function 7 is not used to the state where it is used will be described. As described above, since the slot output from the FIFO 23 is temporally the same as or earlier than the slot output from the slot erase function, the switch 8 is not synchronized with the beginning of the slot and the switch 8 is not used. Switch from to use state. Immediately after the switching, the comparison circuit 26 compares the contents of the slot output from the FIFO 23 with the contents of the slot output from the slot erasure function 7, and inserts an empty slot from the insertion circuit 25 so as not to create a time gap until the contents match. insert.

By the above operation, the slot erasure function 7 is completely used at the time of coincidence, and can be switched without loss of the slot.

As described above, in this embodiment, two opposite directions are used.
There are two bus-type transmission paths, and communication is performed using an isochronous slot and a data communication slot, and a node to be used is determined in advance for the isochronous slot, and the data communication slot is the slot flowing through one of the transmission paths. Using the reserved slot, and transmitting the allocated slot to the other transmission path. The destination node copies all the slots therein, and marks the slot immediately after receiving the slot addressed to the own node among them. In a system in which the slot erasing function provided in each node is in use in advance, in a system in which one slot is accumulated by the function and the slot immediately before the marked slot is made reusable, Install a monitor device at the end,
Monitors slots received from one transmission line within a certain time, and dynamically determines whether or not to use the slot erasure function of each node based on the ratio of data communication slots and the ratio of the number of reservations. The slot reuse method characterized in that the notification is performed using the slot has been described.

Further, four parameters a1, a2, b1, and b2 are externally set, the number x of data communication slots within a fixed time is compared with a1 and a2, and the number y of reserved data communication slots is set as b1. , B2, and whether to increase or decrease the number of nodes using the slot erasure function is determined based on the matrix of 3 rows and 3 columns formed from the magnitude relation. To allow or reduce the use of the middle node at the location where the interval between the nodes is the largest, select the location with the minimum number of nodes included in two consecutive intervals and select the slot in the middle The slot reuse method characterized by canceling the use of the function of the erasure function using node has been described.

Using the FIFO memory, the slot content comparison circuit and the changeover switch, the comparison circuit compares the slot output from the slot erasure function with the slot output from the FIFO memory. Do not read the slot from the memory, and if they match, select the output from the FIFO memory with the switch to release the read restriction of the FIFO memory, and at the same time, do not write the empty slot of the data communication slot to the FIFO memory. The slot reuse method has been described in which the slot erase function is switched from the used state to the unused state by releasing the write restriction of the FIFO memory when the FIFO memory becomes empty.

Further, by using the FIFO memory, the empty slot insertion circuit, the content comparison circuit of the slot, and the changeover switch, the same slot as the slot read from the FIFO memory is read until the slot erase function reads it.
Reading from the IFO memory is prohibited, and during this time, an empty slot for data communication is inserted from the empty slot insertion circuit, and if the same slot is recognized by the comparison circuit, the output from the slot erasing function is selected by the switch. The slot reuse method characterized by switching from a state where the erasing function is not used to a state where the erasing function is used has been described.

Embodiment 2 FIG. Next, as a second invention, an operation for enhancing the effect of the slot erase function 7 in a node using the slot erase function 7 in each node will be described.

FIG. 6 shows the configuration of the slot erase function 7. FIG. 6 shows the state of the state machine 1 from the slot multiplexing unit 11.
2 except that the control line 16e is output for FIG.
Is the same as

The operation will be described below. When the slot release unit 9 releases the slot, it notifies the state machine 12 at that time. At the same time, the state machine 12 gives the reservation canceling unit 15 permission to cancel the reservation. Next, when the released slot is multiplexed with the isochronous slot by the slot multiplexing unit 11 and output, the slot multiplexing unit 11 notifies the state machine 12 that the released slot has been output. The state machine 12 stops giving the reservation canceling permission to the reservation canceling unit 15 after a lapse of a predetermined time from this point if the reservation has not been canceled yet.

In the above operation, how to determine the fixed time is problematic. This is added to twice the simple signal propagation delay with the adjacent node and the fixed delay N + 1 slot time in the buffer of the transmission line 1b on the opposite side. It is suppressed below the thing.

FIG. 7 shows an example of the above operation.
Is 4 slot times, the signal propagation delay time between adjacent downstream nodes is 1 slot time, and the time required for multiplexing with the isochronous slot in the slot multiplexing unit 11 is 5 slot times. In the figure, the arrow 101 on the horizontal axis represents the passage of time. In this case, the reservable cancellation time for the slot received from the transmission line 1b on the opposite side is 16 slots from the time when the slot is released. This means that the possible time is extended for 5 slot times since the conventional system has 11 slot times, and the probability of slot cancellation is increased.

As described above, in this embodiment, the slot for data communication is released from one transmission line, and the reservation of the slot for data communication received from the transmission line on the opposite side is canceled from the point of reusability. The slot reuse method has been described in which a slot can be canceled for a certain time after a slot released after a processing delay in the slot erase function is transmitted to a downstream node.

Embodiment 3 FIG. In the first embodiment, the transmission path on the opposite side is monitored, and information on the use of the slot erasure function 7 is notified using the data communication slot based on the number of data communication slots and the number of reservations within a fixed time. The notification may be periodically performed using an isochronous slot whose use is predetermined in the device 2.

Embodiment 4 FIG. In the first embodiment, processing is performed based on the flowchart of FIG. 2 based on the number of slots for data communication and the number of reservations within a certain period of time. The operation of recognizing the current use state of the slot erasure function based on the information is performed in steps 30b and 30c. This operation is performed in any part of a series of operations unless the order is changed. Is also good.

Embodiment 5 FIG. In the first embodiment, whether the number of nodes using the slot erasure function is increased or decreased is determined from the number of data communication slots and the number of reservations. However, this may be determined only by the former. That is, the operation may be performed by replacing FIG. 3 with FIG.

Embodiment 6 FIG. Next, an embodiment of the third invention will be described. In the first embodiment, the use of the slot erasure function is controlled based on the number of data communication slots and the number of reservations within a certain time, but a fixed delay is applied to the data communication slots provided in each slot erasure function. The capacity of the buffers 13a and 13b to be generated may be changed. In other words, when the buffer capacity of the data communication slot is increased, the reservation cancellation period becomes longer, so that the possibility of canceling the reservation received from the transmission line 1b on the opposite side increases, and the effect of the slot erasure function increases. Conversely, when the buffer capacity decreases, the delay amount in the slot erase function decreases, but the possibility of canceling the reservation decreases, and the effect of the slot erase function decreases.

The operation in the fifth embodiment will be described with reference to FIG. FIG. 9 shows the configuration of the data communication slot buffer 13 in the slot erasing function 7. In the figure, reference numeral 27 denotes a RAM constituting the buffer 13. 2
Numerals 8 and 29 indicate the positions of the write pointer and the read pointer accessing the RAM, respectively. The instruction bit is a bit indicating whether or not the data communication slot is an empty slot. For example, the capacity of the RAM is K + 1 slots (addresses are from 0 to K), and an empty slot for data communication is preset in the address K.
If the fixed delay is i (≦ K) slot time, the positions of the write pointer 28 and the read pointer 29 are separated by i.

When increasing the buffer capacity and increasing the fixed delay, the write pointer 28 and the read pointer 29 are used.
Therefore, the read pointer 29 is moved to the address K while the capacity is being increased. For example, now
In the case where the fixed delay is increased by three slot times assuming that the read pointer 29 is at j, the read pointer 29 is moved to the address K for three slot times, and then returned to the address j + 1. This allows the capacity of the buffer to be changed without loss of slots.

When the buffer capacity is reduced and the fixed delay is reduced, the read pointer 29 is advanced in increments of one slot time, and the indication bit is checked to skip an empty slot for data communication. For example, assuming that the read pointer 29 is at j and the fixed delay is reduced by 3 slot times, an area in which empty slots of data communication slots are stored by 3 slots after j is skipped. This allows the buffer capacity to be changed without loss of slots.

As described above, in this embodiment, the data communication slot is released for one transmission line, the isochronous slot and the data communication slot are separated, and the former is output to the downstream node as it is. For the latter, after a fixed delay is given, it is inserted into the gap of the isochronous slot and then transmitted to the downstream node, and the magnitude of the fixed delay is made variable depending on the state of the slot flowing through the transmission line. As a result of monitoring using claim 1, when the ratio of data communication slots is large or the number of reserved data communication slots is large, the fixed delay is increased and the transmission of data communication slots is delayed. A featured slot reuse scheme has been described.

Embodiment 7 FIG. Next, an embodiment of the fourth invention will be described. In the first embodiment, the operation for enhancing the effect of the slot erasure function in the node using the slot erasure function in each node has been described. However, in this function, the delay time of the data communication slot in the function increases. Although there is a possibility, the following operation can be used from the viewpoint that the delay amount of the isochronous slot that is not related to the slot reuse is set to 0. In other words, if the positions of the slot release unit 9 and the slot separation unit 10 are switched with respect to the transmission line 1a of FIG. 6, and the isochronous buffer 13c of the transmission line 1b is deleted,
Although the delay time of the data communication slot may increase, the delay of the isochronous slot can be set to zero.

FIG. 10 is a diagram showing the configuration of the slot erase function according to the sixth embodiment. The symbols in the figure are the same as those in FIG. FIG. 11 describes a method of setting the PSR bit of the slot following the slot addressed to the own node in the reception processing function of FIG. In the figure, reference numeral 40 denotes a row of slots flowing through the transmission path 1a,
1, DS2, etc. DS indicates a slot for data communication, and IS
1, IS2 and other IS indicate isochronous slots.
An arrow 101 indicates the passage of time.

Next, the operation will be described. If the data communication slot received by each node is addressed to its own node, the PSR bit of the next data communication slot to be received is set to 1. For example, in FIG. 11, if DS2 is addressed to the own node, the PS of IS5 received immediately after
Instead of setting the R bit, 1 is set in the PSR bit of the next data communication slot DS3 to be received.

On the other hand, the operation of releasing the data communication slot marked by the above operation in the slot erase function will be described. As shown in FIG. 10, the slot separating unit 10 at the entrance of the slot erasing function separates the isochronous slot and the data communication slot, and the data communication slot is temporarily stored in the slot releasing unit 9 and the subsequent data communication slot is stored. Wait until it is received, examine the PSR bit when the subsequent slot is received, and if the PSR bit is 1, release the slot stored in the slot release unit 9 and simultaneously To notify that the slot has been released.

In the transmission line 1b on the opposite side, the buffer 13b for applying a fixed delay has a capacity of N slots and the isochronous slot does not require a buffer in order to make the delay time equal to 1a. Also, similarly to the slot releasing unit 9, the reservation canceling unit 15 waits for the received data communication slot once, and transmits the data communication slot when the subsequent data communication slot is received.

In the above operation, when all the slots suddenly become the isochronous slots during the operation of the network, the slot release unit 9 in each slot erasing function is used.
And one data communication slot in the reservation canceling unit 15 respectively. In order to avoid this, after a certain period of time, the slot being stored is changed to the transmission path 1
The a-side and the 1b-side are simultaneously output.

As described above, in this embodiment, only the data communication slot to be reused is passed through the slot erasure function, and each node receives the received data slot only to its own node. For example, the slot for data communication to be received next is marked, and the slot erase function separates the slot for data communication and the slot for isochronous at the entrance of the function, and outputs the isochronous slot to the downstream node as it is. Only the data slot is accumulated until the next data communication slot is received, and at the time of receiving the slot, it is determined whether or not the accumulated slot can be released by the mark written in the slot, and the slot can be released. If it cannot be released, output it as is, and insert it in the gap of the isochronous slot. It described a slot reuse method and transmits to the downstream node.

[0062]

As described above, according to the first aspect of the present invention, the use state of the slots flowing through the transmission path is monitored, and whether or not to use the slot erase function in each node is determined based on the result. Accordingly, when the number of data communication slots is smaller than that of the isochronous slots or when the usage rate of the data communication slots is low, the use of the slot erasure function is stopped, thereby passing the slot erasure function in such a case. Therefore, it is possible to eliminate the occurrence of a delay time.

Further, according to the second aspect of the present invention, the setting of the possible time for canceling the reservation due to the release of the slot can be accurately set, and the effect can be reduced without increasing the amount of delay associated with passing through the slot erasure function. Can be enhanced.

According to the third aspect of the present invention, the number of nodes using the slot erasure function is increased and decreased, and the capacity of the buffer for generating a fixed delay in the erasure function is increased or decreased without loss of slots during communication. be able to.

Further, in the fourth aspect, the delay in the slot erase function for an isochronous slot which is not targeted for slot erase can be set to zero.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration example of a bus-type local area network in a case where a device that monitors a slot on a transmission path is arranged.

FIG. 2 is a diagram showing a flow of an operation in the monitor device.

FIG. 3 is a diagram showing a calculation and determination part of the flowchart shown in FIG. 2;

FIG. 4 is a diagram showing detailed operations of an increase process and a decrease process of the flowchart shown in FIG. 2;

FIG. 5 is a diagram showing a configuration near a switch for controlling use of a slot erasure function in a node;

FIG. 6 is a diagram showing a configuration of a slot erasing function in a node according to the present invention.

FIG. 7 is a diagram illustrating a method of setting a reservation cancellation period after a slot is released.

FIG. 8 is a diagram showing another embodiment of FIG. 3;

FIG. 9 is a diagram illustrating a configuration of a buffer that generates a fixed delay for a data communication slot in the slot erasing function.

FIG. 10 is a diagram showing a configuration of a slot erasing function in a case where a method of causing no delay in an isochronous slot is employed in the present invention.

FIG. 11 is a diagram showing an outline of a reception process of a data communication slot when a method of causing no delay in an isochronous slot is employed in the present invention.

FIG. 12 is a diagram showing a configuration example of a conventional bus-type local area network.

FIG. 13 is a diagram showing a configuration in a node.

FIG. 14 is a diagram showing a configuration of a conventional slot erase function.

FIG. 15 is a diagram showing a format of a slot.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 transmission path 4 node 5 reception processing function 6 transmission processing function 7 slot erasing function 8 switch 9 slot releasing section 10 slot separating section 11 slot multiplexing section 12 state machine 13 buffer 14 slot reception detecting section 15 reservation canceling section 23 FIFO memory 24 FIFO Control circuit 25 Empty slot insertion circuit 26 Comparison circuit

Claims (4)

(57) [Claims] 1. A transmission system having the following elements: (a) first and second buses for transmitting information in a predetermined transmission unit in opposite directions ; (b) at a terminal of the first bus, Monitor means for monitoring the use state of the information of the transmission unit; (c) information generation for generating control information for controlling the use of the transmission unit based on the monitoring result of the monitor means and transmitting the control information to the second bus (D) connected to the first and second buses, receiving the control information from the second bus, and , based on the content, receiving the control information from the first bus .
And a node for changing the use state of the transmission unit of the second bus . 2. A transmission system having the following elements: (a) a bus for transmitting information in a predetermined transmission unit; (b) a use node that reserves use of the transmission unit and uses the transmission unit; A) determining the end of the use of the transmission unit used by the use node, enabling the transmission unit to be reused and transmitting the transmission unit to the bus, and determining the reusable transmission unit from the time of transmission to the bus; A re-use node that cancels the reservation of the transmission unit reserved by the use node during the time of. 3. The system according to claim 1 , wherein the node is transmitted to a first bus.
Receiving the information of the transmission unit, delaying it by a predetermined time, and again
Delay means for transmitting the information to the bus, and generating the information
On the basis of the control information transmitted to the second bus by the means,
A delay unit for changing a delay amount of the delay unit;
2. The transmission system according to claim 1, wherein: 4. A transmission system having the following elements: (a) a bus for transmitting information in a first type and a second type of transmission unit; and (b) a first type transmission unit connected to the bus and transmitted from the bus. And a second type of transmission unit, which separates the first type of transmission unit onto the bus as it is, and stores the second type of transmission unit separated by the separation unit, and stores the second type of transmission unit. And processing means for determining the processing of the stored second type of transmission unit based on the contents of the transmission unit.