JPH0683231B2 - Parallel data transfer method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a parallel data transfer method in a loop transmission system used for local communication.

2. Description of the Related Art FIG. 4 shows a frame structure in a conventional loop transmission system. In FIG. 4, FH is a frame header and SYN
Is a synchronous signal area and ASYN is an asynchronous signal area. ASYN also inserts delimiters to indicate the beginning and end of a series of data to be transmitted to form a data frame,
The structure is such that a token is added to the end of the data frame.

In the frame configured as described above, FH includes information for performing frame synchronization and loop control, area instruction information for distinguishing the synchronous signal area and the asynchronous signal area, information regarding the status of the remote station, and an error detection code. Etc. are stored. Signal transmission between synchronous terminals is performed by time slot management by DA-TDMA control of the center station, and packet transmission is performed by token passing control for signal transmission between asynchronous terminals. Here, the DA-TDMA control is a method in which a transmission line is time-division-multiplexed and used in a demand-assign multiple access method in which a line is allocated according to the occurrence of a call.The token passing control is a transmission called a token. This is a method in which the identifier, which means the right, circulates in a loop-shaped transmission path, and the station that gets the token can send a message. In this token passing control, the station that has obtained the token and transferred the data returns the token to the transmission path immediately after the data transfer and gives another station an opportunity to transfer the data.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the above frame structure, when performing packet transmission between asynchronous terminals, while one station obtains a token and transmits a data frame, another station transmits an urgent data frame. Even if there is a request, since there is no token on the transmission path, it cannot be transmitted unless the transmission of the previous data frame is completed, and if the frame currently being transmitted is very long, the subsequent data frame is kept waiting for a long time. There was a problem. Furthermore, if a fake token that has the same bit pattern as the true token appears in the asynchronous area due to a bit error, etc., it is difficult to determine the location of the token for this, so the station that captured the true token There is also a problem that it is difficult to delete a fake token unless the message sent by is overwritten on the fake token and the fake token is erased.

In view of the above problems, the present invention provides a parallel data transfer method capable of processing data transfer between stations in parallel in a loop transmission system and erasing a false token caused by a bit error or the like. To aim.

Means for Solving the Problems According to the present invention, when a frame circulating on a loop transmission line is composed of a frame header and M slots W having a fixed bit length, a plurality of slots W are combined without overlapping, When N different channels are provided in the frame and the area management of the channel is carried out by having the information associating the channel and the slot in the frame header, a unique bit pattern indicating the usage right is given for each channel. A token composed of an identifier for identifying a channel is arranged, each station has the processing function of the token in parallel with respect to the N channels, and the station receiving the token transmits the channel of the channel. With the right to use, transfer the data to any station, and immediately after transferring the token, It is configured such that it is sent out again on the transmission path and circulated, and the transmission path use right of the channel is given to another station to perform signal transmission between aperiodic terminals.

The present invention has the above-described configuration, and for example, even when one station A acquires the token T ₁ of the channel N ₁ and is transmitting a data frame, another station catches a token of an empty channel other than N _1. Then, the data frame can be transmitted, and the data transfer can be performed in parallel. Furthermore, since the token differs for each channel depending on the channel identifier, even if the token T ₂ of the channel N ₂ occurs in the channel N ₁ due to a bit error etc., this false token T ₂ will use the channel N ₁ . Can be detected and erased at the station.

Embodiment An embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows the configuration of a loop transmission system to which the present invention is applied. In FIG. 1, a center station 1 and remote stations 2-5 for data transmission / reception are connected in a loop by a transmission line 6, and a plurality of asynchronous terminals 7-11 are connected by the loop transmission line via each remote station. Perform packet switching.

FIG. 2 shows an example of the structure of a transmission frame. For simplicity, it is assumed that there are three channels on the transmission path. In FIG. 2, one frame is a frame header FH and M.
Slots _{{W 1, W 2, ......} , W M} is composed of, information for performing frame synchronization and loop control for FH, information for assigning each slot into three channels, the remote station status Information related to the error detection code and the like are stored. Further, three channels formed by combining these M slots without overlapping each other are shown in FIGS. 2 (a), (b) and (c). The structure of the token in FIGS. 2 (a), (b) and (c) is as shown in FIG. 2 (d). In FIG. 2 (d), 20
Is a unique bit pattern indicating the right to use the transmission path,
21 is an identifier for identifying the channel.

The operation of the present embodiment configured as described above will be described below.

Now, assume that in FIG. 1, the remote station 2 has acquired the token T ₂ of the channel 2 of the frame that is being circulated, and has begun to transmit data from the asynchronous terminal 7 to the asynchronous terminal 10 in FIG. The transmission data is written in the slot of channel 2 shown in FIG. 2 (b). If a transmission request is issued from the asynchronous terminal 8 shown in FIG. 1 before the writing of the transmission data is completed, the remote station 2 can use an available channel (for example, channel 1).
The token T _{1 of} is captured and data transmission from the asynchronous terminal 8 is started. Further, even if a transmission request is issued from the asynchronous terminal 9 in FIG. 1 while the data transmission is continuing, the remote station 3 captures the token T ₃ of the empty channel 3 when the frame circulates, and transmits the data. Can start. As described above, if multiple channels for writing transmission data in a frame are provided, even if the transmission of data from one asynchronous terminal is not completed, another channel can be used to transmit from another asynchronous terminal. Can also send data, and data transfers are processed in parallel.

Further, FIG. 3 shows the processing contents from the generation of a data transmission request to a station to the completion of the data transmission.

In FIG. 3, steps 31 to 33 are processes for the station to search for an empty channel token. In step 31, first, a peculiar bit pattern (bit pattern 20 in FIG. 2D) indicating the right to use the channel is searched.

Next, based on the FH channel area management information, the channel is known from the position (slot number) where the bit pattern was detected (step 32). And step 33
At, verify that the channel identifier following the bit pattern matches the channel examined in step 32.

When the token of the empty channel can be detected by the above process, the token is erased from the transmission path to occupy this channel and data transmission is started (step 34). When the data is completed, it is added to the end of the transmitted data frame. A token for the channel is added (step 35), and the circuit is circulated again on the transmission path to transfer data and give another station an opportunity to use the channel. On the other hand, in the determination process of step 33, if the channel identifier does not match the channel checked in step 32, it means that the token pattern of another channel is mixed in the above channel, so a false token is added to the station. Report the detection and perform error processing such as deleting this fake token (Step 3
6).

As described above, in this embodiment, the channel identifier is included in the token pattern, and since the channel of the token is checked at each station, even if a fake token appears due to a bit error or the like, it is detected. Can be removed.

As described above, according to the present invention, a plurality of channels are provided in a frame circulating on a transmission path and data is transferred by token passing control for each channel, so that data transfer can be performed in parallel. Moreover, even if a token of another channel appears in a certain channel due to a bit error or the like, it can be detected and erased, so that its practical effect is great.

[Brief description of drawings]

FIG. 1 is a system diagram showing a configuration of a loop transmission system of an embodiment of the present invention, FIG. 2 is a state diagram showing a configuration of a transmission frame of the embodiment, and FIG. 3 is a flow chart of data transmission of the embodiment. FIG. 4 is a state diagram showing a structure of a conventional transmission frame. 1 ... Center station (CS), 2-5 ... Remote station (RS), 6 ... Transmission line, 7-11 ... Asynchronous terminal, FH ... Frame header, W ... Slot, SYN
…… Synchronous signal area, ASYN …… Asynchronous signal area, 20 …… Unique bit pattern indicating the right to use the transmission path, 21 …… Channel identifier.

Claims (1)

[Claims] 1. A plurality of remote stations which connect asynchronous terminals to a common transmission line configured in a loop to perform data transmission, and a center station which manages and controls a frame circulating on the transmission line at a constant cycle. A loop transmission system is formed as a component, and when the frame is composed of a frame header and M fixed-length slots W, a plurality of slots W are combined without overlapping and N pieces are mutually included in the frame. When different channels are provided and the area management of the channels is carried out with the information associating the channels with the slots in the frame header, a unique bit pattern indicating the channel usage right and an identifier for identifying the channels are provided for each channel. A token consisting of the above-mentioned N channels. In parallel with the token processing function, the station receiving the token acquires the right to use the transmission path of the channel to transfer the data to any station, and immediately after the transfer, the token is re-established. A parallel data transfer method in which signals are sent to a transmission line and circulated, and the right to use the transmission line of the channel is given to another station to perform signal transmission between asynchronous terminals.