JPS617750A - Data transmission control system - Google Patents

Abstract

PURPOSE:To improve the utilizing efficiency of a transmission line with simple processing by providing an interruption output circuit and an interruption detection circuit to a transmission line so as to start reconstitution only when the reconstitution at the circuit network system is required. CONSTITUTION:A data is discriminated by a data judging level 13 of a reception circuit for the level of the transmission line 1 and when the frame is addressed to the own node, a data is fetched to a reception data memory 7. When it is judged that the frame is a token frame representing the right of transmission, a CPU9 stores it to a control memory 10 temporarily that the CPU has the token to output a transmission data in a transmission data memory 8 from a transmission circuit 5 to the transmission line 1 and it is finished, a token frame is generated and fed to the next node so as to erase temporarily the storage of the token in the memory 10 temporarily. Further, an interruption level detection circuit 3 informs always the state of the transmission line 1 to the CPU9 depending on the discriminating level 15 and goes to a tentative master when an interruption is detected while the own node has the right of transmission, the circuit 3 goes to a tentative master to attain reconstitution.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a data transmission control method for a data transmission network system in which a plurality of transmission devices are connected to a bus-like communication medium and communication rights are delegated using tokens, and in particular, the present invention relates to a data transmission control method for a data transmission network system in which a plurality of transmission devices are connected to a bus-like communication medium and communication rights are delegated using tokens. The present invention relates to a data transmission control system that performs the following.

[Prior Art] Generally, in a token bus type network system, in order to circulate the tokens in the order of addresses (node addresses) unique to each transmission device (hereinafter referred to as a node) that makes up the system, the next token destination address must be specified. It is necessary to recognize, memorize, and send a token to the storage address every time, and for this purpose, it is essential to recognize each transmission device that makes up the network system, and the logical ring configuration of the token rotation in the network system. must be aware of.

Therefore, it is necessary to rebuild this logical ring when a new device is added to this logical ring, or when the devices that made up the logical ring are disconnected from the logical ring, such as when the power is cut off. There is.

For this reason, conventional methods for reconstructing logical rings in networks include methods that always perform reconstruction at regular intervals, or methods in which a node joining or leaving a logical ring destroys the data frame flowing on the transmission path. Methods have been used in which the recognized transmission device enters a reconfiguration operation, but these methods involve a lot of loss time in terms of communication medium usage efficiency, which is a serious drawback of the token bus method.

[Purpose] The present invention aims to eliminate the above-mentioned drawbacks of the prior art.It is an object of the present invention to eliminate the drawbacks of the above-mentioned prior art.It is a simple configuration that can be used only when it is necessary to reconstruct a network system without adversely affecting ongoing data transmission. The purpose of this study is to propose a data transmission control method that allows system reconstruction.

[Example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a main block diagram of a transmission device (hereinafter referred to as a node) constituting a data transmission network system according to an embodiment of the present invention, and FIG. 2 is a voltage waveform diagram on a transmission path of the network system of this embodiment. It is.

In the figure, 1 is a transmission line, 2 is a connector that connects the transmission line l and a node, 3 is an interrupt level detection circuit for checking the interrupt request output from another node, and 4 is a transmission line l
5 is a transmitting circuit for modulating and sending data to transmission line 1, and 6 is an interrupt request output for requesting network system reconstruction to transmission line L. 7 is a reception data memory for storing data addressed to the own node received by the reception circuit 4; 8 is a transmission data memory for storing data to be transmitted; 9 is for overall control of the embodiment node. Controlled microcomputer (hereinafter referred to as CPU)
10 is a control memory for the CPU 9, and is a readable and writable memory. 11 is a power-off detection output circuit that monitors the power state of the node and detects a power-off;
The interrupt output circuit 6 is activated by the power-off output from the power-off detection output circuit 11.

Hereinafter, the network system entry control in the node having the above configuration will be explained with reference to the flowchart of FIG. 2.

When the node is powered on, the CPU section 9 first monitors for a certain period of time whether or not a data transmission frame is flowing on the transmission path 1 via the receiving circuit 4 in step S1. and,
If the data transmission frame cannot be detected, step S
Proceeding to step 2, the node recognizes that it is the first entry node in the network system, waits for other nodes to enter the network, and constructs a logical ring around the token of the network.

When a transmission frame is detected in step S1, the logical ring configuration of token circulation of the network system has already been constructed, so the step interrupt output circuit 6 monitors the frame detection signal 20 of the receiving circuit 4 in step S4, A 1iJ]ljl inclusion request is output at certain times between frames that are not in frames. The output timing and output voltage waveform of the interrupt request to the transmission line 1 by the interrupt output circuit 6 are shown in FIG.

In FIG. 3, al and a2 indicate the output timing of the data frame, and the output level of data "1" from the transmitting circuit 5 is 12a, and the output level of data "0" is 12b.

In the receiving circuit 4, the judgment of data "1" and O11 is made based on level 13.

During the time period from when the Cono frame is sent until when the next frame is sent, the interrupt output circuit 6 outputs a time interrupt request shown at 16 at a voltage level shown at 14.

The interrupt level detection circuit 3 uses level 15 as a reference to determine the presence or absence of an interrupt request.

After the interrupt output circuit 6 outputs the interrupt request at the output voltage level 14 for the time indicated by 16 in step S5, the interrupt output circuit 6 outputs the interrupt request again during the next frame in step S4.
Return to

On the other hand, other nodes constructing the network system circulate tokens, which are transmission right delegation commands, to each other, and the node that acquires the token acquires the transmission right and performs data transmission processing.

When the node has acquired this transmission right, the interrupt level detection circuit 3 detects whether an interrupt request is output on the transmission line l.
When it detects this interrupt request, it acts as a temporary master node and rebuilds the logical ring configuration of the network system's token rotation.

For example, this reconfiguration involves confirming responses to all the swords currently composing the logical ring, sending a frame destined for the address between the node address composing the logical ring and the next node address, and It may be determined that the node holding the address has newly entered the logical ring, and the node having the unresponsive address has left the logical ring.

The node that outputs the new entry request to the network system in step S5 monitors whether or not a data frame addressed to the own node has been sent in step S6, and if a frame addressed to the own node is sent, step S7 The interrupt output circuit 7 is reset at step S8, and network entry processing is performed at step S8, followed by normal transmission processing.

When a node participating in the logic ring of the token rotation of the network system is in a power-off state, the power-off detection output circuit 11 promptly detects the power-off and activates the interrupt output circuit 6.

The activated interrupt output circuit outputs the interrupt request shown in FIG. 3 onto the transmission line 1 by processing similar to steps S4 and S5 described above to notify that the own mate is leaving the network system.

In this embodiment, the transmission line 1 is unbalanced transmission, and as shown in FIG. 3, the output level of the data transmission is negative polarity 12a,
The interrupt request is sent between 12b and 14 with a positive polarity opposite to that of data, and is 0゛v when no data transmission or interrupt request is being made.In normal operation, the level on transmission line 1 is Data judgment level 13 of receiving circuit 4
If the frame is addressed to the own node, it is taken into the received data memory 7. When the CPU unit 9 determines that this frame is a token frame representing the transmission right, it temporarily stores in the control memory 10 that it owns the token, and transmits the transmission data in the transmission data memory 8 to the transmission circuit 9. When this is completed, a token frame is created and sent to the next node, erasing the temporary memory of the token held in the control memory IO. The above operations are executed based on microprogramming stored in the CPU section 9. The interrupt level detection circuit 3 always informs the CPU unit 9 of the state of the transmission line 1 at the judgment level 15, and only when an interrupt is detected when the own node has the transmission right, it becomes a temporary mask and starts the rebuilding operation. . Other than that, there is no need to rebuild at all; all you have to do is send the token frame to the next node and process the data transmission and reception, and there is no need to take extra time for the rebuild.

Although this embodiment shows a reverse polarity interrupt on an unbalanced transmission line, it is also possible to make an interrupt request on a balanced transmission line by increasing the output level compared to the output level during data transmission.

[Effects] As explained above, according to the present invention, by providing means for interrupting the transmission path and means for detecting the interruption, it is only necessary to start the reconfiguration operation when it becomes necessary to reconfigure the network system. It is a simple process, there is no wasted time before starting reconstruction, the data being transmitted is not destroyed, and the efficiency of using the transmission path is greatly increased.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram of a transmission device according to an embodiment of the present invention, FIG. 2 is a network entry control flowchart of this embodiment, and FIG. 3 is a voltage waveform diagram for sending out voltage to a transmission line of this embodiment. . In the figure, 1...Transmission path, 3...Interrupt level detection circuit, 6...Interrupt output circuit, 9...CPU section, lO.
. . . Control memory, 11 . . . Power-off detection output circuit. Patent applicant Canon Co., Ltd. Figure 1 Figure 3 Figure 2

Claims (4)

[Claims] (1) In a data transmission control method of a network system in which a plurality of transmission devices are connected to a bus-like communication medium and a transmission right is delegated by circulating a token that is a transmission right delegation command having a destination address, the transmission right is transferred to the transmission device. A data transmission control comprising an output means for outputting an interrupt to a communication medium and a detection means for detecting an interrupt from another transmission device, and a network system is reconstructed by detecting the interrupt by the detection means. method. (2) The data transmission control system according to claim 1, wherein the interrupt output by the output means is an output with a voltage having a polarity opposite to that of the data transmission output. (3) The data transmission control system according to claim 1, wherein the interrupt output by the output means is an output with a voltage having a larger amplitude than the data transmission output. (4) The data transmission control method according to claim 1, wherein the transmission device that has acquired the transmission right when the detection means detects the interruption takes the initiative and rebuilds the network system.