JPH07129496A - Bus control system - Google Patents

Abstract

PURPOSE:To improve the transmission efficiency of a data transmission system where a control station and plural nodes are connected. CONSTITUTION:A control station successively transmits instructions I, II and III by a continuous time slot and these instructions I, II and III are inputted in a remote terminal. The remote terminal designated as the address of the instructions transfers the inputted instructions to a node by the time slot which is the next to the time slot where the instructions are inputted. The remote terminal collects the responses from the node for further transmitting the responses to a response bus by the next time slot.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data bus control system, and more particularly to a data bus control system for a data transmission system in which a plurality of nodes are connected to one control station via a remote terminal.

[0002]

2. Description of the Related Art A conventional data transmission system of this type is
As shown in FIG. 3, a data bus 33 and a plurality of remote terminals 34 are provided between the control station 31 and the plurality of nodes 32.
It is configured by connecting with. The remote terminal 34 is provided to connect a plurality of nodes having different specifications and performances to one data bus 33.

When the control station 31 continuously sends commands to a specific node among the plurality of nodes 32, the next command is transmitted while the specific node is processing the previous command. The data bus is controlled so that it will not be input.
Further, the control station 31 performs data bus control so that responses to commands sent to the plurality of nodes 32 do not collide on the data bus 33. More specifically, the control station 31
Sends an instruction I to the data bus 33, recognizes a response I to the instruction I, and then sends the next instruction as shown in FIG.
Send II. As described above, in the conventional data bus control method, one command is sent from the control station, and after the response is confirmed, the next command is sent so that duplicate processing in the node and data bus Avoiding collisions.

In the conventional data bus control system, the control station 31 sends a next command after performing a time-out process when no response is obtained within a predetermined time.

[0005]

In the conventional data bus control method, in order to avoid duplicate processing at a node and response collision on a data bus, the control station recognizes the response to the previous command and then I'm trying to send out orders. Therefore, there is a problem that the transmission efficiency is low.

Further, if the response from the node cannot be recognized even after a lapse of a predetermined time, the next command cannot be sent until the time-out process ends, which further deteriorates the transmission efficiency. There is a point.

An object of the present invention is to improve the transmission efficiency of a data transmission system in which a control station and a plurality of nodes are bus-connected via a remote terminal.

[0008]

According to the present invention, there is provided a control station, a plurality of remote terminals, and nodes respectively connected to the plurality of remote terminals, the control station and the plurality of remote terminals. In a bus control method applied to a data transmission system in which and are connected by a command bus and a response bus, command transmission from the control station to the command bus is performed at a predetermined cycle timing, and based on the predetermined cycle timing, A bus control method is obtained, wherein the remote terminal determines the timing of transferring the command to the node and the timing of transmitting the response from the node to the response bus by the remote terminal. .

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a data transmission system to which an embodiment of the present invention is applied. In this data transmission system, the control station 11 and a plurality of nodes 12 are connected via a command bus 13a, a response bus 13b, and a plurality of remote terminals 14. The remote terminal 14 is the node 1
The protocol of the transmission data is decoded according to the specification and performance of No. 2, and the communication is controlled between the control station 11 and the node 12 to realize the interface. Also, the instruction bus 13a
Is a bus for transmitting a command from the control station 11 to the node 12, and the response bus 13b is a bus from the node 12 to the control station 11.
Is a bus for transmitting a response to. That is, instruction bus 1
3a and the response bus 13b constitute a unidirectional full-duplex transmission line.

Next, the data bus control system adopted in this data transmission system will be described. Control station 11
2 can send the instruction I, the instruction II, and the instruction III to the instruction bus 13a in consecutive time slots, as shown in FIG. These instructions are specific to one node 12
They may be addressed to different nodes 12 or may be addressed to different nodes 12.

The command I sent from the control station 11 to the command bus 13a in the first time slot is input to all the remote terminals 14. Remote terminal 14
Confirms the destination of the input instruction I, and the remote terminal 14 connected to the node 12 designated as the destination.
Depending on the protocol control information contained in instruction I
The information of the instruction I is transferred to the node 12 in the time slot of and the response from the node 12 is collected (transfer I). Then, the remote terminal 14 converts the response information from the node 12 into a predetermined transmission form and sends the response I to the response bus 13b in the third time slot.

Similarly, for the instruction II and the instruction III, the transfer processing II or III is performed in the time slot next to the time slot in which the instruction II or III is sent to the instruction bus 13a, and the response is made in the next time slot. II or III is sent to the response bus 13b.

Thus, in this embodiment, the instruction bus 13a is used.
Since the control bus 11b and the response bus 13b are provided and the transmission line is a unidirectional duplex transmission line, the control station 11 can continuously send commands regardless of the presence or absence of a response. Also, remote terminal 1
By defining the transfer timing by the No. 4, it is possible to prevent the processing from being duplicated with respect to the continuously sent instructions. Furthermore, by setting the timing at which the remote terminal 14 sends a response, the response bus 13b
You can avoid the collision of responses above.

[0014]

According to the present invention, the data bus connecting the control station and the remote terminal can be unidirectionally duplicated to continuously send the command. Further, by defining the timing of the transfer by the remote terminal and the timing of sending the response, it is possible to avoid duplication of processing at the node and collision of the response on the data bus. As a result, the data bus control method of the present invention improves the transmission efficiency.

[Brief description of drawings]

FIG. 1 is a block diagram of a data transmission system to which an embodiment of the present invention is applied.

FIG. 2 is a diagram illustrating a control sequence according to an embodiment of the present invention.

FIG. 3 is a block diagram of a conventional data transmission system.

FIG. 4 is a diagram for explaining a control sequence of a conventional data bus control method.

[Explanation of symbols]

 11 Control Station 12 Node 13a Command Bus 13b Response Bus 14 Remote Terminal 31 Control Station 32 Node 33 Data Bus 34 Remote Terminal

Claims (2)

[Claims] 1. A control station, a plurality of remote terminals, and a node respectively connected to the plurality of remote terminals, wherein the control station and the plurality of remote terminals are connected by a command bus and a response bus. In a bus control method applied to a data transmission system, an instruction is sent from the control station to the instruction bus at a predetermined cycle timing, and the remote terminal sends the instruction to the node based on the predetermined cycle timing. A bus control method characterized in that a transfer timing and a timing at which the remote terminal sends a response from the node to the response bus are determined. 2. When the command is transmitted from the control station to the command bus at a first timing of the timings of the predetermined cycle, the remote terminal has a second timing that is continuous with the first timing. 2. The bus control according to claim 1, wherein the command is transferred to the node at the same time, and the response from the node is sent to the response bus at a third timing that is continuous with the second timing. method.