JP5396864B2 - Data transfer method between terminal devices - Google Patents

Description

  The present invention relates to a communication system in which a plurality of terminal devices (nodes) are network-connected by a ring-type transmission line, and more particularly to a data transfer method between terminal devices.

  This type of communication system is used in a wide variety of control systems that use computers, such as plant monitoring and control systems and automation factory process centralized management systems.

  As a data transfer method between terminal devices connected to a network, for example, there is a method that enables output from a device connected to a network via a ring-type transmission path to a plurality of output devices in one transmission frame (for example, Patent Document 1). , See Patent Document 2).

  In these conventional systems, each terminal device once captures the received data frame and reconstructs the data frame. For this reason, each terminal device has network configuration information and a function of editing the received data frame.

Japanese Patent Laid-Open No. 10-23050 JP 11-338523 A

  In the methods of Patent Document 1 and Patent Document 2, since data frames are once reconstructed from the reception operation to the transmission operation in each terminal device, the time for which the data frame stays in each terminal device becomes longer. The transfer speed tends to decrease.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a data transfer method between terminal devices that eliminates the need to reconstruct data frames, simplifies data transfer processing, and increases the data transfer rate.

  In order to solve the above-mentioned problem, the present invention causes a data frame and a token frame to circulate in a transmission path between terminal apparatuses connected to a network via a ring-type transmission path, and the terminal apparatus that has detected the token frame ends its reception. The token frame is transmitted later so that only one token is circulated on the transmission path, and the terminal device having the transmission request transmits the token frame after receiving the token frame and after transmitting the data frame, and receives the data of the data frame The terminal device that performs data reception in parallel with the passage of the data frame to the downstream terminal device, and the data frame that has passed through each terminal device is erased by circulating to the terminal device of the transmission source, It is characterized by the following configuration.

(1) A data transfer method between terminal devices in a communication system in which a plurality of terminal devices are connected via a ring-type transmission line,
Each terminal device
Means for circulating data frames and token frames in the transmission path;
Means for transmitting a token frame after completion of reception when detecting the token frame;
If there is a transmission request, means for transmitting the token frame after receiving the token frame and after transmitting the data frame;
Means for receiving data in parallel with the passage of the data frame to the downstream terminal device when receiving data of the data frame;
When transmitting the data frame, means for erasing when a data frame that has passed through another terminal device circulates to its own terminal device;
It is provided with.

  (2) Each of the terminal devices is characterized in that the transmission time of the token frame is longer than the sum of the internal delay times of all the terminal devices, and the transmitted data frame is returned during token transmission.

  As described above, according to the present invention, a data frame and a token frame are circulated through a transmission path between terminal apparatuses connected to a network via a ring-type transmission path, and the terminal apparatus that has detected the token frame receives a token after completion of the reception. A terminal that circulates only one token on the transmission path by transmitting a frame, and a terminal device that has a transmission request transmits a token frame after receiving a token frame and after transmitting a data frame, and receives data of the data frame The device receives data in parallel with the passing of the data frame to the downstream terminal device, and the data frame that has passed through each terminal device is circulated to the terminal device of the transmission source and erased. Can be eliminated, the data transfer process can be simplified, and the data transfer speed can be increased.

  Specifically, since the data frame is not reconstructed in each terminal device, the processing is less than in the conventional method, the internal delay of the terminal device is reduced, and the transfer rate is increased.

  Further, since the data frame is not reconstructed in each terminal device, the processing is less than in the conventional method, and the control circuit of the terminal device can be simplified.

  Also, the transmitted data frame can be erased from the transmission path without being aware of reception.

The block diagram of the communication system which shows embodiment of this invention. The schematic diagram of data transfer operation.

(Embodiment 1)
FIG. 1 is a configuration diagram of a communication system showing an embodiment of the present invention. Each of the terminal devices 1 to 6 is assigned slot numbers 0 to 5 and is connected to the network through a ring-type transmission line, and the data frame and the token frame are circulated through the transmission line between the terminal devices.

  As shown in FIG. 1, this frame configuration includes a flag for synchronization between a transmission source node and a transmission destination node before and after a frame, a command type in which the type of whether the frame is a data frame or a token frame, and It consists of a data part such as a source address, transmission data, and check code.

  When each of the terminal devices 1 to 6 detects a token frame, it transmits the token frame after the reception is completed, thereby circulating only one token on the transmission path. Further, among the terminal devices 1 to 6, the terminal device having a transmission request transmits a data frame after completion of the token frame reception, and transmits the token frame after the transmission. Also, the terminal device that receives the data frame data receives data in parallel with the passage of the data frame to the downstream terminal device, and the data frame transmitted on the transmission path is different from the token frame in each terminal device. It is erased when it passes through and goes to the terminal device of the transmission source (only the terminal device confirms but does not retransmit).

  With such a frame configuration and processing at the terminal device, each terminal device eliminates the need to reconstruct the data frame, simplifies the data transfer process, reduces the time that the data frame stays in each terminal device, and reduces the data transfer rate. Raise.

  The terminal devices 1 to 6 shown in FIG. In addition, although a component is shown with a hardware, you may make these into a software structure. In the terminal device 3, when the received frame from the upstream node is a token frame, the token detector A detects the token frame when the command type field is received, and the multiplexer B outputs its own transmission data (own transmission data). ) Side to suppress the passage of received frames. The delay circuit C delays the received frame more than the time until the token detector A detects the token frame, and delays the flow of the token frame downstream. At the end of token reception, if there is no transmission request, a token frame is output from the terminal device, and the token frame is circulated through the transmission path. When there is a transmission request, first a data frame is transmitted, and a token frame is transmitted after transmission. In any case, at the end of token frame transmission, the multiplexer B switches the output from the own transmission data side to the reception data from the upstream via the delay circuit C. With this operation, the terminal device passes the data frame through the delay circuit C, so that the frame can be propagated only by the delay time of the delay circuit C. This propagation time is compared with the conventional frame reconstruction operation. Processing is simplified.

  FIG. 2 is a schematic diagram when the terminal device 3 (slot 2) performs a data transfer operation. In each terminal device (slots 0 to 5), when detecting the token frame, the token frame is transmitted after completion of the token reception. Here, the terminal device having a transmission request transmits a data frame after the end of token reception, and transmits a token frame after transmission. Unlike the token frame, the data frame sent on the transmission path passes through each terminal device, and is erased when it reaches the transmission source terminal device. In the terminal device that receives the data frame, the reception operation is performed in parallel with the passage downstream.

(Embodiment 2)
In the first embodiment, like the data frame transmitted by slot 2 in FIG. 2, the transmitted data frame is erased when it reaches the terminal device of the transmission source. As a precondition, the transmitted data frame needs to be returned during the token frame transmission. After the token transmission, the multiplexer B becomes a data frame passing output, so if the data frame returns after the token transmission, it flows again downstream. Therefore, the transmission time of the token frame is made longer than the sum of the internal delays of all slots, so that the transmitted data frame is returned during the token transmission. As a result, each terminal device can always delete the transmitted data frame at the transmission source without being aware of reception.

1-6 Terminal device A Token detector B Multiplexer C Delay circuit

Claims (1)

A data transfer method between terminal devices in a communication system in which a plurality of terminal devices are network-connected by a ring-type transmission line,
Each terminal device
Means for circulating data frames and token frames in the transmission path;
Means for transmitting a token frame after completion of reception when detecting the token frame;
If there is a transmission request, means for transmitting the token frame after receiving the token frame and after transmitting the data frame;
Means for receiving data in parallel with the passage of the data frame to the downstream terminal device when receiving data of the data frame;
When transmitting the data frame, means for erasing when a data frame that has passed through another terminal device circulates to its own terminal device;
A data transfer method between terminal devices, characterized in that the transmission time of the token frame is longer than the sum of the internal delay times of all the terminal devices, and the transmitted data frame is returned during token transmission .

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