JPH024042A - Communication terminal equipment - Google Patents

Abstract

PURPOSE:To successively transmit transmission data by outputting a successive transmission request when the remaining transmission data are successively transmitted at the time of a transmission completion and suspending the successive transmission when a reception to reject the successive transmission is executed. CONSTITUTION:When the transmission request exists, the transmission data are edited to a data frame with a fixed length, and the number of transmission frames is stored into a DPRAM 6. When the number of transmission frames is 4 or below, the data are transmitted by the number of frames, and the DPRAM is '0'-cleared after an I/F 4 completes the transmissions of all data. On the other hand, when the number of frames exceeds 4, the frames with the fixed length are transmitted from the I/F 4 successively in 4 frames. When the transmission is completed, 4 is subtracted from the number of frames of the DPRAM 6. There, when the transmission from the other terminal is not executed at all in a definite time, the transmission of the frame is continued. When an NAK frame to reject a successive request is received, a token is transmitted, the transmission right of the other terminal is transferred, and the transmission is temporarily suspended.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a communication terminal device that connects to a local area network using the token access method.

[Prior Art] - In the local area network (LAN) token access method, communication terminal devices (hereinafter referred to as terminals) are arranged in a ring, and a specific signal or frame called a token is circulated on the ring. This method grants access rights to the transmission medium. In order to avoid transmission line conflicts, only one token exists on the LAN, and the terminal that receives the token acquires the right to transmit on the transmission line. Tokens are sequentially received and passed among all terminals on the LAN, and all terminals can always obtain the right to transmit after a certain waiting time. When receiving and passing this token, in the conventional token access method, once a terminal has received a token, it must receive the next one after a certain period of time or after transmitting a certain length of data, in order to avoid monopolizing the token. The system involved passing a token to a terminal.

[Problems to be Solved by the Invention] However, in the above conventional example, even when one terminal transmits a large amount of data such as image data, the token is not sent after a certain period of time or after sending a certain length of data. It has the disadvantage that it is not suitable for burst transfer of large amounts of data that needs to be transferred to the next terminal and requires real-time performance.

The present invention was made to solve the above problems, and
An object of the present invention is to provide a communication terminal device that can continuously transmit data between communication terminal devices connected to a local area network using a token access method.

[Means for Solving the Problem] In order to achieve the above object, the communication terminal device of the present invention has the following features:
It has the following configuration. That is, it is a communication terminal device connected to a local area network using the token access method, and includes a transmission means that transmits transmission data when receiving a token, and transmission data that must be continuously transmitted after the transmission by the transmission means is completed. continuous transmission request means for outputting a continuous transmission request when the continuous transmission request is received; transmission interrupting means for transmitting a token to the other device and interrupting the continuous transmission when receiving a continuous transmission rejection response from another device; and a transmission rejection means that outputs a continuous transmission rejection response when the transmission is rejected.

[Function] When a token reception is received, the transmission data is transmitted, and when the transmission ends, if the remaining transmission data is to be transmitted continuously, a continuous transmission request is output, and if there is a reception that rejects the continuous transmission, continuous transmission is performed. Acts like interrupting.

[Embodiment] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[Description of File Server (FIG. 1)] FIG. 1 is a block diagram of a file server 1 that is an embodiment of the present invention. As shown in the figure, the file server l includes a LAN control unit 2, a dual port RAM (DPRAM) 6, a main CPU 7 of the file server, and a main CPU (7).
It is composed of a ROM 8 and a hard disk device (DISK) 9 that stores data files. The file server 1 is connected to a LAN transmission path 11 via a directional coupler 10, and stores large-capacity data files that can be read and written from each terminal on the LAN. among them,
The LAN control unit 2 includes a sub CPU (S-CPU) 3, L
AN interface unit (I/F) 4, 5-CP described later
ROM (S-ROM) that stores the U3 program
) 5 and DPRAM 6, and controls the transmission and reception of each frame. Next, DPRAM6 is the main CPU
This RAM can be accessed from both the main CPU 7.7 and the 5-CPU3, and enables high-speed data transfer between the main CPU7.

The transmission path 11 of this embodiment is a bidirectional transmission path used in cable television, and uses a frequency division multiplexing method (token bus method of IEEE802.4) as a transmission method.

Furthermore, each terminal uses the directional coupler 10 to connect the transmission path 1
1 and easily connected.

[Description of transmission method (Fig. 2)] The file server 1 of this embodiment receives a read command for a data file in DISKe from another terminal connected to the LAN, and transmits the desired data file to another terminal. The case of transmitting to a terminal will be explained below with reference to FIG.

As shown in the time chart of Fig. 2, when the file server 1 receives the token 21 and obtains the right to transmit data, frames 22 to 25 in which the transmission data file is edited into data frames of a certain length are consecutively transmitted. and sent out onto the transmission line 11. However, if the number of frames to be transmitted exceeds 4 frames, after continuously transmitting the above four frames 22 to 25, a continuous transmission request frame 26 is transmitted, and the presence or absence of a transmission request from another terminal is determined by the NAK frame 32. do. If there is no transmission request from another terminal, the remaining frames 27 to 30 are transmitted, and then when a NAK frame 32 is detected on the transmission path for the second continuous transmission request frame 31, a token 33 is sent. is sent to the downstream terminal, and the continuous transmission by the file server 1 ends.

[Explanation of operation (Figs. 3 and 4)] Next, using the case of transmitting the above-mentioned large-capacity data file as an example, the operation of the 5-CPU 3 of the LAN control unit 2 will be explained in Figs. 3 and 4. This will be explained below according to the flowchart.

First, the CPU 7 searches the DI SK 9 based on the index information and writes the corresponding data file to the DPRAM 6. After writing the data to the DPRAM 6, the CPU 7 generates an interrupt signal 12 to the 5-CPU 3 and requests transmission. Let me know something. On the other hand, 5-CPU3
Wait for the above token to be received for you via /F4, and then when that token is received, the third
In step SIO shown in the figure, it is determined whether there is a transmission request. Then, if there is no transmission request, step S
The token is transmitted in step 22, and the process ends. but,
If there is a transmission request, in step S12, the transmission data is edited into a fixed length data frame as described above, and the number of transmission frames is stored in the DPRAM 6. Next, in step S14, the number of transmitted frames is compared with the number of consecutive transmitted frames in this embodiment, and if the result is that the number of transmitted frames is 4 or less, step S2
6, send data for the number of frames and send r/F4
After transmitting all data, in step S28, the DPRA
Clear the number of frames stored in M6 to "O". on the other hand,
In step S14, if the number of frames exceeds 4, the process proceeds to step S16, and four consecutive frames of a certain length are transmitted from the I/F 4. When the I/F 4 finishes transmitting the 4-frame data, 4 is subtracted from the number of frames stored in the DPRAM 6 in step S18. Next, in step S20,
Send the above-mentioned continuous transmission request frame from I/F4,
After the transmission is completed, as determined in step S22, that is, if there is no transmission from another terminal within a certain period of time, the process advances to step S14 to continue frame transmission.

However, if a NAK frame rejecting the continuous transmission request is received from another terminal within the time, a token is transmitted in step S24, and the transmission right is passed to the other terminal. Then, the transmission is temporarily interrupted and resumed the next time the token is received.

Next, the 5-CP when a continuous transmission request frame is received.
The operation of U3 is as shown in the flowchart of FIG.
If there is data to be transmitted or if it exceeds the processing capacity, a rejection frame (NAK frame) is transmitted, and if there is no data to be transmitted, nothing is done. Here, the continuous transmission request frame is a request frame for all terminals connected on the LAN, and there is a possibility that NAK frames are transmitted simultaneously from a plurality of terminals. In this case, transmission line 1
The frame above 1 becomes an unreadable frame due to frame collision. Therefore, the NAK frame reception determination at step S22 in FIG. because,
This is because if all other terminals accept the continuous transmission request, there will be no frames on the transmission path 11.

It is also possible to prioritize transmission data according to its urgency and determine whether to request continuous transmission based on its brightness. Furthermore, when a request frame is received, it may be determined whether or not to return a NAK frame depending on the priority of its own transmission data.

According to this embodiment, by providing a continuous transmission request frame in a token bus type LAN, it is possible to quickly transmit a large amount of data that requires real-time performance.

[Effects of the Invention] As explained above, according to the present invention, data can be continuously and quickly transmitted between communication terminal devices connected to a local area network using the token access method. There is.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a file server that is an embodiment of the present invention, Fig. 2 is a timing chart of frames on a LAN transmission path, Fig. 3 is a flowchart during data transmission, and Fig. 4 is a continuous transmission request frame. It is a flowchart at the time of reception. In the figure, 1...File server, 2...LAN control unit, 3...5-CPU14...I/F, 5...5-
ROM, 6...DPRAM, 7...CPU, 8...
・ROM. 9...DISK, 10...Directional coupler, 11...
- LAN transmission line, 12... Interrupt line. Figure 2 Figure 4

Claims (1)

[Claims] A communication terminal device connected to a local area network based on the token access method, which has a transmission means that transmits transmission data upon receiving a token, and transmission data that must be continuously transmitted after the transmission by the transmission means is completed. continuous transmission request means for outputting a continuous transmission request; transmission interrupting means for transmitting a token to another device and interrupting continuous transmission when receiving a continuous transmission rejection response from another device; and rejecting continuous transmission requests from other devices. 1. A communication terminal device comprising: a transmission rejection means for outputting a continuous transmission rejection response when a continuous transmission rejection response is received.