JPS60250742A - Access control method of transmission line system - Google Patents

Abstract

PURPOSE:To execute efficiently access processing concentrating nodes by providing a means for setting up the maximum number of frames to be sent at the individual catching of a token frame by each node and sending plural frames out of the maximum number of frames to be sent at the catching of the frame. CONSTITUTION:A receiver 2 and a transmitter 3 are connected to a system transmission line 1 and the receiver 2 is connected to the transmitter 3 through a bypass and also connected to a processor bus 11 through a receiving buffer 4. A main control part 8 connected to the bus 11 is connected to the receiver 2 through a frame sort decoder 7. A processor 9, memory 10 and a transmission buffer 5 are connected to the bus 11 and the receiving and transmitting buffers 4, 5 and a frame formation circuit 6 are controlled by the control part 8. A maximum frame number setting circuit and a RAM for storing the number of frames in the buffer 5 and a counter for storing the number of transmission frames at the reception of a token frame are formed in the circuit 6. At capturing the token frame, plural frames out of the maximum sending number of frames can be sent.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an access right acquisition control method in a transmission line system.

[Prior art]

Communication between multiple meters via bus or loop7
Various methods have been proposed regarding access control methods in transmission line systems. Among them, the token control access method, in which a special frame called a token is circulated on a path or loop, and a node that wants to access acquires access rights by capturing the frame, has an excellent method of achieving high transmission path usage efficiency. It has characteristics.

By the way, the token control method that has been put into practical use is based on the premise that the communication load is distributed to each node, and normally the node that captures the token frame will send out the only data or control frame and then release the token. The frame is released and the access acquisition tank is passed to another node.

However, in a system where access frequency is biased toward a specific node, for example, in a system where various input/output devices are connected to a processor, all input/output devices communicate with the processor node, so access to the processor node F is difficult. will be concentrated.

Normally, a processor that controls input/output devices has a finite reception and transmission queue for communication with the input/output devices, and processes are leveled out.6. numbers tend to average out. moreover,
There are many types of processing in which reception processing and transmission processing are sequentially linked.

When performing the above processing, in a method in which the node that captures the token frame transmits the only data or control frame, the acquisition of the right to transmit is lower than the possibility of reception at the node where processing is concentrated, and the possibility of receiving and The send queue becomes unbalanced.

The result 1. The reception processing queue in the browser increases, causing reception rejections. When considering the efficiency of the entire transmission system, a vicious cycle occurs in which a large number of frames become invalid due to rejection of reception, and as a result, the possibility of the access-intensive node acquiring the transmission right decreases, which reduces the effective efficiency of the transmission system. The disadvantage was that it decreased. Furthermore, the limited number of output frames means that the transmission and reception capabilities of the processor are limited by transmission processing, which also reduces the efficiency of the entire system.

[Purpose of the invention]

An object of the present invention is to eliminate the above-mentioned drawbacks, and to make it possible to transmit a plurality of data or control frames within a preset range when acquiring an access right, thereby providing a transmission path where there are mates with concentrated access. The objective is to provide an effective and highly efficient system.

[Structure of the invention]

In order to achieve the above object, the access control method according to the present invention provides a transmission line system in which acquisition of access rights between nodes is controlled by capturing circulating token frames, in which each node connected to the transmission line is individually controlled. The apparatus is provided with means for setting a maximum number of frames to be transmitted when capturing a token frame, and by this means, it is possible to transmit a plurality of frames within the maximum number of frames to be transmitted when capturing a token frame.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of a transmission line system in which access is concentrated at one node, in which a single processor and a plurality of input/output (10) devices are connected to a loop-shaped transmission line. Most of the communication is between the processor and the IO devices, and there is relatively little (or no) communication between the IO devices.

The processor in the transmission line system executes processing using a queue as shown in FIG. 2 in its transmission/reception processing. In order to process the entire system efficiently, it is necessary to balance the processing of the reception queue and the transmission queue.

FIG. 3 shows a block diagram of a node (in the example of FIG. 1, a processor) where accesses are concentrated, as one embodiment of the present invention. The transmission path l is coupled by a receiver 2 and a transmitter 3,
The receiver 2 is connected by a bypass path to the transmitter 3 and to the receive buffer 4 and frame type decoder 7. The transmitter 3 is connected to a transmission buffer f5 and a frame generation circuit 6. The processor 9 and the main memory IO are connected via the processor bus 11 to the reception buffer 4, the transmission buffer 5, and the main control section 8 of the transmission path node.

The main control unit 8 operates the receive buffer 4, the transmit buffer 5 . and controls transmission and reception of the frame generation circuit 6.

In the above system, the node monitors the signal received from the receiver 2 for token frames in order to gain access to the transmission path. When the token frame is received, a plurality of pieces of data stored in the transmission buffer 5 in advance are transmitted from the transmitter 3 to the transmission path l. Here, the signal on the transmission path l needs to be formatted into a frame in a desired format, and the frame generation circuit 6 adds control signals before and after the transmission data. After transmitting the data, the token frame is transmitted to the transmission path 1 again.

The function of transmitting a plurality of frames within a preset number of data frames when receiving a token frame, which is a feature of the present invention, is executed by the circuit of the main control unit 8. In order to realize the above functions, the control unit 8 includes a maximum frame number setting circuit (switch, ROM data), a register (or RAM) that stores the number of frames in the transmission buffer, and a transmission frame number setting circuit when receiving a token frame. It is equipped with a number counter and performs control to send a predetermined number of data frames to the transmission path 1. In addition, in order to enable simultaneous transmission of a plurality of data or control frames, it is provided with a circuit (or firmware) that can simultaneously process a plurality of response frames to a transmission frame.

Next, the movement of frames during transmission is shown in FIGS. 4 and 5. Node A is the processor, node B is the processor.

C and D are IO device nodes.

FIG. 4 shows the frame movement of a conventional system in which only one frame is transmitted when a token frame is captured, for comparison with the present invention. In the figure, "T II" indicates a token frame, and "A + B" indicates a data or control frame from node A to node B.

The node that has received the token frame transmits the transmission data frame onto the transmission path, and then releases the token frame. When the reception queue exceeds a specified value, reception is rejected. At time to in Figure 4, a reception rejection occurs at node A, and the reception frame is appended with a rejection flag °R' and sent back to the sending mate.This increase in the number of rejection frames means that a large number of invalid data are being sent. This means that the data goes around the transmission path and requires retransmission of the data, which reduces the efficiency of the transmission path.

FIG. 5 is a diagram showing the movement of frames when the present invention is implemented, and the maximum number of frames to be transmitted is set so that only a specific node (node A in this case) is allowed to simultaneously transmit a plurality of frames. Even if a large number of access requests are set in the transmission queue of node A, it is possible to transmit multiple frames, so it is possible to equalize the transmission and reception ratio of the node where accesses are concentrated (here, node A). It is possible to improve the transmission efficiency of the system.

〔Effect of the invention〕

As explained above, the present invention is a transmission line system in which access rights are acquired by capturing token frames, and a node that has gained access rights is able to transmit multiple frames with a predetermined maximum transmission frame number of several yen. By doing this, even in systems where access is concentrated on a specific node, it is possible to eliminate bias in the number of transmitted and received frames, and system efficiency such as an increase in invalid frames and processing capacity limited by the number of transmitted frames can be improved. This has the effect of eliminating the causes of deterioration and realizing a highly efficient transmission line system.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the connection form of the transmission line of the present invention, and FIG.
The figure is an explanatory diagram conceptually showing the processing of the processor, Fig. 3 is a block diagram showing an embodiment of a device implementing the present invention, Fig. 4 is a time chart explaining the conventional system, and Fig. 5 is the invention of the present invention. 2 is a time chart explaining in detail. 1: Transmission path, 2: Receiver, 3: Transmitter 4: Reception M buffer, 5: Transmission buffer 6: Frame generation circuit, 7: Frame type decoder, 8: Main control unit 9: Processor, lO: Main memory 11 : Processor bus patent applicant NEC Corporation Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] In a transmission line system in which acquisition of access rights between nodes is controlled by capturing circulating token frames, each node is provided with means for individually setting the maximum number of frames to be transmitted when capturing token frames, and the means allows the above-mentioned number of frames to be transmitted when capturing token frames. An access control method for a transmission line system, characterized by making it possible to transmit multiple frames within the maximum number of frames to be transmitted.