JPS62232226A - Load controller - Google Patents

Abstract

PURPOSE:To apply optimum load control even when a node station is subscribed to a system newly by allowing each node station to reserve a function inquiring about the waiting number for data processing to other node station when the titled controller is incorporated in a multiple address communication system. CONSTITUTION:A counter 17 is controlled directly by a microprocessor 8, incremented by 1 when a frame sent from other node station or its own node station is received, and decremented by 1 at each prescribed period by a timer built in the microprocessor 8. A node station subscribed newly detects a POL to recognize an idle line, outputs a PSV signal to occupy the line. Then a pattern representing a field inquiring about the waiting number for data processing waiting is set to a control frame C and a frame setting a pattern representing the multiple address communication to a destination address DA is sent to the line. Then the POL signal is sent to release the line thereby awaiting the reply from the other station.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plurality of node station devices on a common transmission path.

[Conventional technology]

A communication in which one of a plurality of node stations connected to each other by a transmission system transmits information that is received by all other stations is called a broadcast communication. In this communication system, f-data sent to each node station is once stored in a reception buffer frame by frame and processed sequentially, but there are limits to the number of reception buffers and processing speed, so these limits must be overcome. If seven frames are sent one after another at a speed exceeding this, the node station will become overloaded, so it is necessary to carry out control to prevent this from happening, and tb load control. As a conventional control method for this purpose, Japanese Patent Application Laid-Open No. 57-5445
As described in No. 3, etc., a load reporting area is set up at a fixed position on the transmission frame, and this area is used to notify the transmitting side of the load status (how many frames are waiting to be processed). I was using it.

[Problem that the invention seeks to solve]

In the above conventional technology, when a new node station joins the system, the load on other stations increases.

In other words, since the load on the line is not known, when this station transmits data, other stations are often overloaded.

SUMMARY OF THE INVENTION An object of the present invention is to provide a load control device in a broadcast communication system that can perform optimal load control even when a new node station joins the system.

[Means for solving problems]

The above purpose is to provide each node station with a counter for counting the number of data processing queues, that is, the number of frames of received data remaining in the reception buffer, and to increase the number of data processing queues by 1 each time data is received from the transmission path.
Then, every time a certain period set so that the time required to process one received frame at the node station does not fall below the maximum value, the number of data processing queues described above is reduced by 1.
This is achieved by providing each node station with the function of inquiring the number of data processing queues mentioned above from other node stations when incorporated into a broadcast communication system.

[Effect]

In a broadcast communication system, data reception is performed in the same way at each node station except the transmitting node station. Since each node station has the above-described function of adding and subtracting the number of data processing queues, it is possible to grasp the load status of its own node station. Also, at the sending node station, by adding the number of data transmissions instead of the number of data receptions to the number of data processing queues above, the sending node station can have the same number of data processing queues in its own counter as other node stations. .

%/-h" If you input the data processing queue from any existing node station by querying the data processing queue for the data processing queue.

This number is the same everywhere, so it is possible to match the number of data processing queues of all node stations.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

The second factor shows one form of a system to which the present invention is applied.91 In this example, each terminal device 1i19 is connected to a ring-shaped common transmission path 2 via a node station 1. However, it goes without saying that the transmission line 2 does not have to be ring-shaped.

Figure 3 shows an example of a frame S used for exchanging data between each node station on a transmission path; hb
, I) A is the destination node station address,
In a broadcast communication system, global address values are set. C is a control field and is used for the control sieve of each node station. SA is the source node station address, DA'f'A is the transmitted/received data, li
``O8'' is a frame error check pattern, and F is a delimiter to indicate the beginning and end of the frame.

FIG. 1 shows an embodiment of a node station 1 to which the present invention is applied. The received signal from the transmission path 2 is demodulated and reproduced through the receiver 3, and detected as a received frame by the frame control circuit 6.

At the same time, the pattern detector 11 detects a special control pattern (here, POL/RSV pattern.
is a data transmission permission signal and nsv is a line occupancy M indication signal) are detected, and these detection signals are input to the selection signal generation circuit 7 to cause the selection circuit 13 to select the data to be transmitted. It is input to the table input port 5 that the processor 8 can view as its status information.

If the data in the 7-nome format detected by the frame control circuit 6 is one-time communication data, the information in the data part is converted to 8-bit parallel data, and the data is randomly accessed via the bus 18. The data is stored in a reception buffer in the memory (AM) 10.

The frame control circuit 6 turns on the interrupt signal 14 to the microgross set t8 when it has received the pre-date at the end of the transmission frame, and sends the read-only memory (RO
M) Start the control program in 9. Also, an abort pattern (a pattern that is neither a synchronization pattern nor data) in the received data.

(occurs during unfinished data transmission 3), the frame control circuit 6 detects this and communicates it to the microprocessor 8 as an imprint signal 15. The demodulated reproduced data is sent directly from the modulator 4 to the transmission line 2 via the selection circuit 13 when the station is in the receive one-word mode.

When this node station sends data to another node station, the frame control circuit 6 takes in the transmission data in the random access memory lo,
Convert to serial data.

Delimiter F1 Destination Address DA-fff'lR Coat C.

A destination address SA etc. are added to the signal, and the signal is sent from the transmitter 4 via the multiplexer 13. When this data passes through the loop and enters the receiver 3, it is checked once in the frame control circuit 6.

If there is an error, it is communicated to the microprocessor 8 by an interrupt signal 16.

The counter 17 is directly controlled by the microprocessor 8, and is incremented by 1 each time it receives a frame sent from another node station or its own node station, and is decremented by 1 at regular intervals by a timer built into the microprocessor t8. It is something that

Figure 4 shows the microprocessor 8 in the node station.
This figure shows the processing when transmitting data. When a transmission request for broadcast communication occurs, the node station waits for POL indicating that the line has been released! When a4VC is entered and )'OL is detected, the station sends out 几sv, occupies one slot, and then sends out 7 frames including a DA field indicating that broadcast communication is not possible. After sending this frame, the value of the counter 17 is incremented by 1 and the value of the counter 17 is checked. This is.

If it is smaller than the number N of reception buffers provided in the memory 10 (this is the maximum number of frames waiting to be processed; all stations do not have more buffers than this), it will immediately send a POL to release the line and allow other stations to use it. Make it possible to send. However, if the value of the counter 17 is greater than or equal to N, if the next VC broadcast communication is performed immediately, some station will be overloaded, so the PO
L & Send. Here, the fixed time T is the value set in the case of T≧To, assuming that To is the time that takes a long time to process one frame at each node station, and one hour has elapsed. In this case, the first broadcast communication can be performed since the processing for l frames is surely completed at every station. Therefore, when the value of the counter 17 is greater than or equal to N, the transmission of the POL is delayed by T, the line is occupied during that time, and the load is controlled by prohibiting relay communication from other stations.

Since the station that performs this transmission and other stations always process one frame every time the above-mentioned time T elapses, one receive buffer is always free. Therefore, by a processing system not shown.

Each station is arranged to perform a process of decrementing the value of the counter 17 by 1 every time T. In addition, the node station that received the data when the broadcast communication was performed increases the value of the counter in its own station for each reception.
By keeping 1.

All node stations can have the same number of data processing queues in the internal counter 7, and the load can be controlled to prevent overload.

Next, the processing method when a new node station is added will be explained using chart 70 in FIG. First of all, at the new node station.

It detects POL, confirms that the line is free, and outputs a psv signal to occupy the line. Then, a pattern is set in the control frame C to inquire about the number of data waiting to be processed, indicating that the number of 7,000 digits will fail, and a pattern indicating that a one-time report communication will be sent is set to the destination address DA, and a frame is sent to the line. Then, send the POL-+ signal to release the line,
Waiting for response from other stations.

When an existing node station on the 1g1 line detects that the control field C of the received frame indicates an inquiry about the number of data processing queues, it checks to see if a signal POL indicating line availability is present on the line. The node station that first detects this POL immediately
It issues a signal and occupies the line, then sets a pattern in control field C to indicate that it is a response frame to one inquiry, and enters the number of data waiting to be processed (the value of kakunta 17 in its own station) in the data field. Create a response frame and send it to the line. When a node station that has newly joined the system receives this frame, it takes out the number of waiting data processing from the data section and sets it in the counter 17 within its own station. At this time, although not shown in the figure, other node stations also receive this response frame and confirm that the number of data processing queues therein matches the value of the counter 17 of their own node station. Know that there is a response to the inquiry.

〔Effect of the invention〕

As is clear from the above embodiments, according to the present invention, a node station that has joined the Shinkyu system can also accurately know the load status of the line at the time of joining, and can control its transmission and functions based on this information. Therefore, when the load on each node station in the system is high, data transmission from the new node station can prevent the processing load on each node station from exceeding its limit.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of a node station to which the present invention is applied, FIG. 2 is a diagram showing an example of the configuration of a broadcast communication system, FIG. 3 is an explanatory diagram of a transmission frame, and FIG. FIG. 5 is a flowchart showing the operation of the node station of the embodiment shown in FIG. 1 during transmission. FIG. 5 is a flowchart showing the operation of each station when the node station of the embodiment of FIG. 1 newly joins the system. 1... Node station, 2... Common transmission path, 6
. . . frame control circuit, 7 . . . selection signal generation circuit,
8...Microprocessor, 9...Read-only memory. 10... Random access memory, 13... Multiplexer, 17... Counter.

Claims (1)

[Claims] 1. A load control method for a broadcast communication system in which multiple stations are connected via a common line, and a station that has acquired transmission rights has the function of broadcasting to all other stations via the common line. Each station is equipped with a receive buffer that stores received data frame by frame and a counter that counts the number of frames waiting to be processed in the receive buffer. All transmitting stations and receiving stations increment the count value of the above counter in their own stations by 1, and wait for a period of time that is not less than the longest time required to process one frame of data across all stations. Each time the wait time is set in each station, the count value of the above counter in each station is decremented by 1, and when a new station is connected to the system, an inquiry frame is sent from the new station in broadcast communication format. When the station that has acquired exclusive rights to the line after receiving the inquiry frame returns the count value of the counter within its own station, the new station shall set the count value to the counter within its own station. In addition, when any station monopolizes the line and transmits, the count value of the counter in its own station will be updated to the above-mentioned reception value held by each station after the transmission is completed. A load control device characterized in that it checks whether the number of buffers is greater than or equal to a minimum value, and if it is greater than or equal to the minimum value, the line is released from the occupied state after the waiting time has elapsed.