JPS59140745A - Data transfer system - Google Patents

Abstract

PURPOSE:To uniform the opportunities for using a circuit by adding an ACK function and a priority control function and improving transmission efficiency, and varying the allotted time of each terminal. CONSTITUTION:None of terminals performs transmission a specific time (T1) after signal transmission. A station which receives a signal in a period of time T1 transmits an ACK signal. A terminal which is to make a request to send starts transmission in its allotted time after the time T1. In this case, a low-priority station (e.g. terminal N+1) has less opportunities for transmission. For this purpose, not T1, but T3 (>T1+T2XN) is allotted to the station as said constant time to evade its contention with terminals 1-N.

Description

[Detailed Description of the Invention] (a) Technical Field of the Invention The present invention relates to a data communication system in which a plurality of terminals are connected to the same line and data is exchanged between each terminal using a contention method. ζ Like the overtime management system of a building management system, a large number of overtime notification terminals have many opportunities to acquire lines, and processing terminals that receive and process these notifications have almost no opportunity to acquire lines, but multiple types of processing The present invention relates to a data transfer system that can be constructed using a simple circuit and simple program processing in a data communication system in which it is necessary to improve multi-processing efficiency by performing multiple processing operations, and which also provides high processing efficiency for a processing terminal.

(b) Prior Art and Problems - A data communication system in which multiple terminals are connected on a line and data is sent and received using each packet using a contention method is capable of transmitting data using simple circuits and simple program processing. There is a transfer method that the present applicant applied for in 1958, which allows the establishment of the Tohaku system. This data transfer method will be explained below.

FIG. 1 is a conceptual diagram of a data communication line, in which contention type data terminals 1 to N are disconnected from a line 10. Figure 2 is a block diagram showing the circuit configuration of a conventional end latch section.The signal from the line 6 is sent via a receiver 16 to a busy detection circuit 15 (the details of which will be explained later) to determine whether the line is in use. The serial signal is converted into a parallel signal by the serial/parallel conversion circuit 14, and the microprocessor (hereinafter referred to as 1'!vlP)
After the overload processing (referred to as 'U') 12, the parallel signal is converted into a serial signal by a parallel-to-serial converter 13 and transmitted to the line via a driver 17. At this time, various instruction programs are stored in the instruction storage ROM II, and the MPU 12 reads out and processes these instructions. )
In ~(6), 18i is the i counter, 19 is the AND circuit, and 2
0 indicates an inverter, 1, time signature) to ■) correspond to points b - e of the block diagram (5), and (B) is a time chart of the circuit signal, which is the reset signal for the counter 18, and ( C) is a time chart of a clock signal (DJ is a time chart of a busy signal, and ▪) is a time chart of a clock signal sent to the counter 18.

The busy detection circuit shown in FIG. 3(5) is a circuit for performing baseband transfer in an asynchronous manner, and determines whether or not the line is in use based on the presence of data input to the reset terminal of the counter 18. In the start-stop synchronization procedure, it is normally held at the level, and when sending out a character, 0 appears randomly once for each character, so the counter is set to 1 every time a character is sent out.
8-, the output of Q6 of the counter 18 is reset to O, indicating that the line is busy.
Notify 2. When the line is no longer in use and the line signal is
When the L/bevel hold is applied, the output of Q6 of the counter 18 is as shown in FIG.
12 will be notified. Also, due to this level signal, the clock to the clock terminal of the υ counter 18 is held at O level as shown in FIG. 3 (3). When each terminal receives a signal, it is determined that it always returns a response signal under the control of the MPU 12 shown in FIG. The terminal recognizes that the line is busy.In other methods, the busy detection circuit can be implemented using a front circuit similar to that shown in Fig. 3.

Fig. 4 is a time chart when securing a line in the conventional example, and Fig. 5 is a flow chart of the transmitter IflL'L in the conventional example.
1, and is transmitted under the control of the QMPU 12 according to the procedure described below.

First, the terminal checks whether the line is busy using the busy detection circuit 15 shown in FIG. If not busy and fc, each terminal is allocated time T 2 X, N (Tt is 1
(where N is the number of terminals), wait for T2 x N time as shown in Figure 4 (C), check again that the line is not busy, and then transmit. Do the following. Each terminal is set to become busy by the busy detection circuit 15 during the time T shown in FIG. 4 after the line is used, so that tax evasion can be avoided first, and after the busy state is released, the time T shown in FIG. The time T2×N is the time allocated to each terminal so that the transmitter is provided to each terminal. For example, if the terminal with the Mth address is busy when attempting to send a message, it will wait until the busy state is released as shown in Figure 4 (B), and then confirm that the line is not busy again after T2xM time and try sending again. Let's do it. If it is busy, repeat the above operation.

When a message is sent to the Send I# operation, a response is always sent back from the receiving terminal using a shake hand, and the receiving terminal returns the response within the above-mentioned one-hour bus time. If a response is returned, this is the end. If the sending terminal does not receive a response until the line busy is released after sending, it determines that a collision has occurred, and retransmits according to the above procedure.

Also, even if there is a response, if it is an error signal, it will be retransmitted,
For example, if a response is not returned even if 31 retransmission is performed, or if the signal is an error, a final notification signal is issued and the process is terminated. In this way, a data communication line can be constructed using a simple busy detection circuit consisting of one counter and one AND circuit with an in-hanitor, and a relatively simple transmission procedure (program). Transmission times are assigned to prevent collisions between terminals, and efficient data transmission is performed.

However, for example, if terminal N in FIG. 1 has little chance of acquiring a line but is performing multiple types of processing, if this terminal N also transmits, the busy detection circuit 15 indicates that it is busy. After detection, you have to wait until your own station acquires a transmitter, and during this time the processing cannot be done, which is inefficient.Also, if you use an interrupt to clear the busy state, the inefficiency will not be as bad as in the above case, but the line This has the disadvantage that an interrupt is generated each time the busy state is released, and the processing is temporarily interrupted, making the processing complicated.

(C) Object of the Invention In view of the above-mentioned drawbacks, the object of the present invention is to configure a data communication system using a simple circuit and simple table 70-gram processing, and to perform multiple processing in most cases when a line is acquired. The purpose of the present invention is to provide a data transfer method that has good processing efficiency and simple processing for processing terminals.

(d) Structure of the Invention In order to achieve the above object, the present invention always returns a response signal to the receiving terminal in response to transmission from each terminal, and the first terminal that has the most opportunity to acquire the line is The terminal has a busy detection circuit for store-1 which determines that the line is in use during the time when the line-use hind limb response signal is returned, and after the line is released from use, a means for sending the message to address 1- of each terminal; When each terminal transmits from time to time while the line is in use, the terminal with the last address in the above order waits for a period of time to transmit, and then the line is in use again. If a response is not returned after transmitting data and canceling the use of the line, provide a means to retransmit data according to the above procedure, so that the second category of terminals, which have the most opportunities to acquire the line, are given the same method as the first category of terminals. A second busy detection circuit that keeps the line in use for a time longer than the busy detection time plus the time the terminal with the largest address waits to obtain a transmitter, and special treatment in which the second busy detection circuit is not busy. This data transfer method is characterized by having a means for transmitting data without any data transmission.

(e) Embodiment of the Invention An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 1 to N are terminals with many parties that acquire a line, and N+1 (not shown) is a terminal that acquires a line. I will explain it as a terminal that has almost no opportunities. Terminals 1 to N have the same configuration as described in the conventional example.

Therefore, terminal N+1 will be explained below.

' Fig. 6 is a time chart when acquiring a line according to the embodiment of the present invention, Fig. 7 is a flowchart of the transmitting means according to the embodiment of the present invention, and Fig. 8 is a block diagram of the busy detection circuit according to the embodiment of the present invention. It is a diagram.

Components in FIG. 8 that have the same functions as those in FIG. 3 are indicated by the same symbols. 1
8' indicates a counter. The main part of the configuration of terminal N+1 is the second one.
As shown in the figure, the busy detection circuit 15 is connected to terminals 1 to N.
The program of the transmitting means stored in the ROMII is also different from that of terminals 1 to N, as will be explained below.

Although not shown, this terminal also uses a RAM and the like to generally perform multi-@f processing A, B, C, . . . song M in parallel. A8 the busy detection circuit of terminal N+1
To explain using a diagram, the point in Figure 8 that is different from Figure 3 is the line! The signal line that notifies the MPU 12 of FIG. 2 that it is busy is replaced by the output of counter 18 Q in FIG. The point is that By doing this, as shown in FIG. 6, the time that the line is busy from the end of line usage is T.

Then, the terminal N with the largest address sends a message (time to obtain a signal) In Figure 816, the line is busy for a time greater than T+ + T2 It is possible to transmit the signal without competing with signals 1 to N. Therefore, as shown in FIG. 7, the signal is transmitted immediately if the store is vacant, as shown in FIG.

In this way, terminal N+1 can transmit immediately when the line is free, so other processing is not interrupted, processing efficiency is high, and system processing does not become complicated. If the timing for detecting the line busy is determined to be detected, for example, at the time when processing M is completed, the processing will not be interrupted any further.

Therefore, the terminal N+1 can also perform the s operation using a simple circuit and a simple transmission processing procedure, and other processing can be performed efficiently using a simple table processing procedure.

(f) Effects of the Invention As explained in detail above, according to the present invention, a data communication system of the tensile type can be constructed using a simple circuit and a simple transmission processing procedure, and there is almost no chance of acquiring a line. This has the effect of allowing multiple processes to be performed.

[Brief explanation of the drawing]

Figure 1 is a conceptual diagram of a data communication line, Figure 2 is a block diagram showing the circuit structure of the main parts of a conventional terminal, and Figure 3 is a block diagram of a conventional busy detection circuit and the signal times of each part. Figure 4 is a time chart when acquiring a line in the conventional example, Figure 5 is a flowchart of the transmission procedure in the conventional example 1-1fit+6, Figure 7, and Figure aE8 are the lines in the embodiment of the present invention. FIG. 2 is a time chart, a flowchart of a transmitting means, and a block diagram of a busy detection circuit when acquiring a line for a terminal that has almost no chance of acquiring a line. FIG. In the figure, 1 to N are terminals, 10 is a line, and 11 is a ROM. 12 is a microprocessor, 13-digit parallel-to-serial converter, 14
15 is a serial/parallel converter, 15 is a busy detection circuit, 16 is a receiver, 17 is a driver, 18.18' is a qualifier, 19 is an AND circuit, and a 20U inverter. Fist 1 〉 2 Year 3 Kuchi (B $4 B Day 2 665th 52 7A RT Leaf 6 Kuchi 7 Kuchimine 8 Kuchi

Claims (1)

[Claims] In a data communication system where multiple terminals are connected to the same line and data is exchanged between each terminal using a contention method, the receiving terminal always returns a response signal in response to a transmission from each terminal. In this year, the first type of terminals that have many chances to acquire the line are equipped with a first busy detection circuit that determines that the line is in use even during the time when the line use hind limb response code is returned, and after the line is released, Means to have a transmitter in the order of the address of each terminal, and when each terminal is transmitting when the line is not in use, wait for the terminal with the last address in the above order to have a transmitter, and then turn the line again when the line is not in use. Means for acquiring the lineFor example, if each terminal sends data and no response is returned after the line is released, the second type of terminals, which have little chance of acquiring the line, should have a means to retransmit data according to the above procedure. , a second busy detection circuit configured to be in use for a time longer than the busy detection time of the first class terminal plus the time for which the terminal with the largest address waits to obtain a transmitter; A data transfer method in which the I$j feature is that the second busy detection circuit has a means for transmitting data without waiting for special requests when the second busy detection circuit is not busy.