JP4127591B2 - Loop type data transmission system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a loop type data transmission system suitable for data transmission of a transmission line having a long transmission line and including a transmission delay element such as a railway control system.
[0002]
[Prior art]
In recent years, various data transmission network systems have been developed with the development of communication technology. Conventionally, in such a system, there is a loop type data transmission system in which a center (control station) for controlling a railway train and a plurality of stations are connected in a loop shape, and FIG. 8 is a diagram for explaining this. It is.
[0003]
A center transmission device 51 constituting the primary station and a transmission device 52 constituting the secondary station installed at each station (1) to (4) form a loop network via the transmission line 53. A plurality of computers # 1 and # 2 are connected to the center transmission device 51, and a personal computer (hereinafter referred to as a personal computer) 54 and a station control device (station system) 55 are connected to the transmission device 52 of each station. .
[0004]
In such a data transmission system for train control, the distance between the transmission devices 52 is as long as several kilometers, so that the transmission speed suitable for long-distance transmission is relatively low (several hundred bits / second to several tens of kilobits / second). V. As long as a modem conforming to the standard such as 32 is used and the transmission of the primary station is not permitted, the secondary station employs a 1-to-N data transmission system in which data cannot be transmitted. For example, an SDLC (Synchronous Date Link Control) method proposed by IBM Corporation is used.
[0005]
This SDLC data transmission system uses data frames arranged as shown in FIG. The flags arranged in this data frame are frame synchronization detection data, DA is a destination address, a control unit is information used for transmission control, an information unit is information on the application side, and FCS (Frame Check Sequence) is for frame error detection It is data.
[0006]
The feature of this SDLC system is that there is one primary station and a plurality of secondary stations in the system, and the transmission device 52 of each station (1) to (4) which is a secondary station can transmit a data frame. As shown in FIG. 10, it can be transmitted only when polling (POLL) is received as a transmission permission signal from the center transmission apparatus 51 of the primary station.
[0007]
Therefore, for example, when the frame I1C is transmitted from the transmission device 52 of the station (1) to the transmission device 52 of the station (3), the transmission device 52 of the station (1) is * 1 [I1C: station (1) to station (1). When the polling is received from the center transmission device 51 as shown in 3), the transmission data frame I1C is transmitted to the center transmission device 51. The center transmission device 51 converts the received frame I1C into a frame IC3 [same as I1C] addressed to the transmission device 52 of the station (3) and transmits it to the transmission device 52 of the station (3) (* 1 in the figure).
[0008]
When data is exchanged between secondary stations in this way, the data is always transmitted to the target secondary station via the primary station as shown in FIG.
[0009]
[Problems to be solved by the invention]
Therefore, when the SDLC method as described above is used, the following disadvantages have been pointed out.
[0010]
(1) A plurality of frames cannot be present on the loop transmission line 53. As a result, the idle time Ts may always occur in the transmission line 53.
[0011]
Normally, the distance of one loop is short, there is no delay in each transmission device, the transmission speed of the frame is high, and the beginning of the frame returns through the loop before the transmission end of the transmitted frame is completed. In this case, there is no vacant time Ts on the transmission line, and even if there is a little vacant time Ts, there is almost no problem.
[0012]
However, for example, in a network system having a time delay element in a transmission device, such as a railway control data transmission system, a considerable amount of time is required until the beginning of the frame returns through a loop after completion of frame transmission. take time. Further, since frame transmission of the secondary station is possible only when transmission is permitted on the primary station side, only one frame can exist simultaneously on the loop transmission line. For this reason, frames cannot be transmitted continuously, the idle time Ts on the transmission path becomes long, and the transmission efficiency is poor.
[0013]
(2) The data transmission system between stations is 1: N, and N: N data transmission is not possible. That is, in order to realize N: N data transmission between stations, it is necessary to perform direct data transmission from the station 1 to the station 3, but the conventional data transmission method uses a data frame from the station 1 once. Since the data is transmitted to the center transmission device 51 and the center transmission device 51 decodes the content of the frame and transfers it to the station 3 again, it is only a so-called 1: N transmission. Therefore, there are problems that the procedure is complicated and that data transmission takes time.
[0014]
(3) When the primary station stops functioning, transmission of the entire system becomes impossible. In other words, there are systems having a recovery function in which the secondary station detects “stop of the primary station” and switches to the primary station, but processing such as switching timing and priority of switching stations is quite complicated.
[0015]
The present invention has been made based on the above circumstances, and can perform N-to-N data transmission, improve transmission efficiency, prevent failure before it occurs, detect failure early, and identify the location of the failure. An object of the present invention is to provide a more reliable loop type data transmission system.
[0016]
[Means for Solving the Problems]
  In order to achieve the above object, the invention according to claim 1 is a loop-type data transmission system in which a plurality of transmission devices are connected in a loop via a transmission line, wherein each transmission device includes a frame transmission system, A frame reception system and an internal clock are provided, respectively. When the frame transmission system receives a data transmission request from the outside, it creates a frame having a destination address field and a transmission source address field on the head side, and sends it to the transmission path. Is to send,Place the time data for fraud frame determination near the beginning of the frame, the frame reception system, when receiving a frame, before the completion of reception of all 1 received frame block, to determine the correctness of the received frame,The destination address and source address of the field are compared with the own address, and when any address does not match the own address, the received frame is relayed to the downstream device, and when any address matches the own address The received clock is removed from the transmission line, and the internal clock sets time data of its own transmission device in the transmission frame and is received when a frame is received from an adjacent transmission device in a loop. This is a loop data transmission system that corrects the internal clock of its own transmission device from the time data in the frame and has a function of synchronizing the time of each transmission device.
[0018]
  In order to achieve the above object, the invention according to claim 2 is a loop-type data transmission system in which a plurality of transmission devices are connected in a loop via a transmission line, wherein each transmission device includes a frame transmission system, A frame reception system and an internal counter are provided, respectively. When the frame transmission system receives a data transmission request from the outside, the frame transmission system creates a frame having a destination address field and a transmission source address field on the head side, and sends it to the transmission path. Is to send,Place the time data for fraud frame determination near the beginning of the frame, the frame reception system, when receiving a frame, before the completion of reception of all 1 received frame block, to determine the correctness of the received frame,The destination address and source address of the field of the received frame are compared with the own address, and when any address does not match the own address, the received frame is relayed to the downstream device, and any address is When they match, the received frame is removed from the transmission path, and the internal counter has a count value representing a time interval in the transmission frame, and from the count data in the frame received from another transmission device in the loop A loop type data transmission system having a function of correcting an internal counter of the own station.
[0020]
  In order to achieve the above object, a third aspect of the present invention provides a loop-type data transmission system in which a plurality of transmission apparatuses are connected in a loop via a transmission line, wherein each transmission apparatus includes a frame transmission system, a frame transmission system, and a frame transmission system. Each receiving system and an internal clock are provided, and when the frame transmission system receives a data transmission request from the outside, a destination address field provided at the head side and a time field for discarding illegal frames and time correction provided at the head side And creating a frame with a source address field and sending it to the transmission path,Place the time data for fraud frame determination near the beginning of the frame, the frame reception system, when receiving a frame, before the completion of reception of all 1 received frame block, to determine the correctness of the received frame,The destination address and source address of the field of the received frame are compared with the own address, and when any address does not match the own address, the received frame is relayed to the downstream device, and any address is When they match, the received frame is removed from the transmission path, and the internal clock sets the time data of its own transmission device to the transmission frame and receives the frame from the adjacent transmission device in the loop. This is a loop type data transmission system which corrects the internal clock of the own transmission apparatus from the time data in the received frame and has a function of synchronizing the time of each transmission apparatus.
[0022]
  In order to achieve the above object, a fourth aspect of the present invention provides a loop-type data transmission system in which a plurality of transmission apparatuses are connected in a loop via a transmission path, wherein each transmission apparatus includes a frame transmission system, a frame transmission system, and a frame transmission system. Each receiving system and an internal counter are provided, and when the frame transmission system receives a data transmission request from the outside, a destination address field provided at the head side and a time field for discarding illegal frames and time correction provided at the head side And creating a frame with a source address field and sending it to the transmission path,Place the time data for fraud frame determination near the beginning of the frame, the frame reception system, when receiving a frame, before the completion of reception of all 1 received frame block, to determine the correctness of the received frame,The destination address and source address of the field of the received frame are compared with the own address, and when any address does not match the own address, the received frame is relayed to the downstream device, and any address is When they match, the received frame is removed from the transmission path, and the internal counter has a count value representing a time interval in the transmission frame, and from the count data in the frame received from another transmission device in the loop A loop type data transmission system having a function of correcting an internal counter of the own station.
[0024]
  In order to achieve the above object, the invention according to claim 5 is as follows. Each transmission device adds to the transmission frame as a time field of the internal clock at the time of frame transmission, and transmission time information in the frame transmitted from the transmission station is not required to be rewritten in subsequent regenerative relaying. 5. The function according to claim 1, further comprising a function of determining the normality of the received frame based on a time difference from the transmission time information in the received frame caused by a step of the internal time of the own apparatus. The loop-type data transmission system described.
  In order to achieve the above object, the invention according to claim 6 determines a transmission load in units of time based on time data or count data in a frame transmitted / received by each transmission device and a size of the transmission frame. 5. The loop type data transmission system according to claim 1, wherein the loop type data transmission system has a function.
  In order to achieve the above object, the invention according to claim 7 has the failure state data of the own transmission device in the transmission frame, and the failure state data of the transmission device in a frame received from another transmission device belonging to the loop. 2. A function of grasping a failure state of a transmission device and a transmission line adjacent to the own transmission device, and a function of detecting a failure of the own transmission device and the transmission line that cannot be detected from the own transmission device. It is a loop type data transmission system according to any one of claims 4 to 4.
  In order to achieve the above object, the invention according to claim 8 is characterized in that the failure occurrence return of the local station detection and the failure occurrence return information received from the adjacent station are integrated in time units, statistics are taken, and the failure occurrence frequency in time units is obtained. 8. A loop type data transmission system according to claim 7, whereinIt is.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0027]
(Example of basic configuration of data transmission system)
FIG. 1 is a block diagram showing a configuration example of a railway control data transmission system to which a loop type data transmission system according to an embodiment of the present invention is applied.
[0028]
In this railway control data transmission system, as shown in FIG. 1, a transmission device 3 of each station (1) to (4) is sequentially connected in series to a center transmission device 1 as a primary station via a transmission line 2. Constitutes a loop-like network.
[0029]
Computers # 1 and # 2 for managing train operations are connected to the center transmission device 1, and the center transmission device 1 transmits the transmission devices at the stations (1) to (4) according to instructions from these computers # 1 and # 2. A control signal is transmitted to 3.
[0030]
On the other hand, a personal computer (hereinafter referred to as a personal computer) 5 and a station control device (station system) 6 are connected to the transmission devices 3 of the stations (1) to (4). Each personal computer 5 is used for information management at each station (1) to (4) and for notifying the management information to the center transmission device 1 and other stations. Each station control device 6 is a train called an electronic interlocking device. It has a role to control the traffic lights.
[0031]
FIG. 2 is a diagram illustrating an example of the module configuration of each transmission apparatus 1 and 3. Each transmission apparatus 1, 3 is provided with an MPU (microprocessor) 11. A bus line 12 derived from the MPU 11 has a recording medium 13 for recording a program and fixed data necessary for program execution, and a serial interface. (SIF) 15 to 18 are connected.
[0032]
As the recording medium 13, for example, a magnetic disk, a magnetic tape, a CD-ROM or the like is used. However, a DVD-ROM, a floppy disk, an MO, an MD, a CD-R, a memory card, or the like may be used. Good.
[0033]
Connected to the serial interfaces 15 and 16 are modems 19 and 20 each having a transmission speed of about 600 bps to 28800 bps. The modems 19 and 20 are connected to adjacent transmission apparatuses 1 and 3 to form a loop network.
[0034]
The serial interfaces 17 and 18 are connected to the computers # 1 and # 2 or the personal computer 5 and the station control device 6, respectively.
[0035]
Further, each transmission device 1, 3 can transmit at any time unless the frame is being relayed. If the frame is being relayed, the transmission data is stored in a temporary transmission waiting buffer in the recording medium 13, and transmission is started when the relay is completed.
[0036]
On the other hand, when a frame to be relayed is received during data transmission, the frame data is stored in the temporary relay waiting buffer in the recording medium 13, and relaying of the frame is started when the data transmission is completed.
[0037]
FIG. 3 is a diagram showing a connection configuration of transmission lines in the present embodiment.
[0038]
The stations a to e are the transmission apparatuses 1 and 3 shown in FIG. These have two transmission lines S1 and S2 and two reception lines R1 and R2, and transmission data received from the reception line R1 by a software program stored in the recording medium 13 of each transmission device 1 and 3 Is transmitted to the transmission line S2 and the transmission data received from the reception line R2 is retransmitted to the transmission line S1 (repeat function for relaying to other stations), and received from the transmission line S1 to the left adjacent station via the transmission line. By connecting to the line R2 from the transmission line S2 to the reception line R1 of the right adjacent station, the clockwise direction (clockwise: broken line in the figure) Y-loop direction and counterclockwise (counterclockwise direction: solid line in the figure) X A loop transmission path in the loop direction is formed.
[0039]
FIG. 4 shows the configuration and type of a frame transmitted by a station connected to the loop transmission line. The transmission frame includes a frame header portion in which five data of a destination address field (DA), a control field (CF), a time field (TF), a transmission station address field (SA), and a serial number are incorporated, and system (application) information. An information part to be set and an FCS (Frame Check Sequence) data part used for frame data error verification are configured.
[0040]
The types of transmission frames are roughly divided into general frames shown in FIGS. 4A and 4B, broadcast frames and priority frames shown in FIG. 4A, and monitoring frames shown in FIG. 4C. Among general frames, there is no information part in a frame used for an initial transmission procedure or a transmission error recovery procedure.
[0041]
Broadcast frames are used for broadcast transmission, priority frames are frames that are relayed / retransmitted with priority over general frames and broadcast frames, and monitoring frames are stations that are adjacent to the own station via a loop transmission path ( It is used for exchanging information with the X and Y loops.
[0042]
The identification of these frames is determined by the frame type bit set simultaneously with the destination address DA shown in FIG.
[0043]
Since this transmission system is capable of N: N transmission, the above-mentioned general frame, broadcast frame, and priority frame may receive frames transmitted from other stations to other stations other than the own station. It has a repeat function (hereinafter referred to as retransmission relay) for promptly relaying to a downstream station.
[0044]
The monitoring frame is limited to information exchange between the own station and the adjacent station, and when the monitoring frame is received, the retransmission is not performed to the downstream station, but the monitoring data is discarded immediately after being captured.
[0045]
From these, general frames, broadcast frames, and priority frames pass through multiple stations from transmission to reception of the destination station, so transmission delay time due to retransmission relay processing (determining whether it is addressed to own station / other stations from DA value reception) Software processing time + α) occurs, and the time interval required for communication between stations differs depending on the connection position of the station, whereas the monitoring frame is only for communication with adjacent stations, so the time width required for communication between stations Is almost uniform across all stations.
[0046]
Therefore, TF (time field) attached to general frames, broadcast frames, and priority frames is used for discarding illegal frames, and TF attached to monitoring frames is used for time correction for inter-station tuning.
[0047]
The transmission of the monitoring frame is performed by all stations connected to the loop at a predetermined period set in advance in the transmission system. However, since it is a frame that is also used for time correction, the station that arrives later arrives in sync with the station that arrives first and makes a stable correction. The monitoring frame can be transmitted from the own station after the tuning with the adjacent station is completed.
[0048]
The function of individual data in the frame header will be briefly described.
[0049]
The destination address DA is the station address to which the frame is notified, and when a received frame is generated, it is determined from this value whether it is addressed to the own station. However, the sender's own station address is set only in the broadcast frame, and the absorption discard by the transmitting station after the broadcast frame circulates is made efficient.
[0050]
Further, the destination address DA includes frame type bits (for 3 bits) as shown in FIG.
[0051]
CF (control field) is an HDLC (high level data control) -like transmission procedure control code.
[0052]
In the TF (time field), the time (or count) data of the transmitting station at the time when this frame is generated is set. The time data is incremented by a one-second cycle (a specified cycle of the system in the case of count data) by a soft timer managed in the station.
[0053]
When receiving the frame, this time data is read, and if it deviates from the local time by a certain range or more, the frame is regarded as an illegal frame and discarded, and retransmission relay is not performed even if the destination address DA is addressed to another station.
[0054]
In 1: N transmission, the secondary station always performs retransmission of received data, but the primary station does not perform retransmission, so even if an invalid frame (such as abort data) is mixed in the loop, the secondary station does not perform retransmission. Is always discarded by the primary station, but in N: N transmission, all the stations repeat the retransmission and do not have the primary station equivalent, so each station in the loop determines whether the received frame is correct or not. Frame detection and prompt discard are required. Time data used for determining an illegal frame is placed near the beginning of the frame, and whether or not the frame is correct is determined before the reception of all one received frame is completed.
[0055]
Also, when the station indicated by DA in the frame goes down, the normal frame circulates and stays in the loop, but after the specified time has elapsed, the TF in the frame becomes an invalid value, so any station in the loop Is absorbed and discarded.
[0056]
SA (source address: transmitting station address) is a transmitting station of a frame, and is used to identify from which station the station that received the frame has transmitted.
[0057]
The serial number is used for discarding a frame received at the last arrival of frames transmitted simultaneously from the X and Y loops. The serial number is set to the same value in both the X-loop frame and the Y-loop frame generated as the outgoing frame, and informs the receiving station that it is the same frame.
[0058]
The serial number data is common to general frames and broadcast frames, and is counted up every time a certain frame is transmitted. For priority frames, serial number data managed separately is provided, and it corresponds to overtaking of general frames and broadcast frames.
[0059]
Also, since the monitoring frame is not relayed and only the communication between adjacent stations is made, the same frame is not transmitted in both the X and Y directions, and thus is not used for the monitoring frame.
[0060]
(First embodiment)
In the first embodiment, the following configuration is added to the basic configuration described above. Each transmission apparatus is provided with an internal clock in addition to the above-described frame transmission system and frame reception system, and has the following functions. Each internal clock sets the time data of its own transmission device in the transmission frame, and corrects the internal clock of its own transmission device from the time data in the received frame when a frame is received from an adjacent transmission device in the loop. It has a function of synchronizing the time of each transmission device.
[0061]
In this case, the time used for the correction of the internal clock is the local time of the system installation location, and an initial value (time) is given with any one of the stations connected to the loop transmission line as a reference station (equivalent to the master station). In the time field TF in the monitoring frame, the reference station and the station whose time correction has been completed set the second time from 0 to 59 for transmission, while other stations that have not been corrected to the reference time go to the reference time. Until the correction, the count value updated in the range of 64 to 127 is set as time data in the time field TF and transmitted. The station that has received the monitoring frame adjusts its own time to the time field TF value in the monitoring frame when the time field TF value in the monitoring frame is larger than the time value of the local station management. The transmission cycle is also synchronized with this.
[0062]
However, the reference station does not adjust to the time data of other stations and keeps the time update timing of its own station. Stations that have been matched with a time value of less than 60 seconds have been corrected to the reference time, and subsequent time updates use seconds from 0 to 59.
[0063]
In the first embodiment described above, the time of all the transmission apparatuses (all stations) connected to the transmission path can be tuned by providing the apparatus for setting the time only at the reference station.
[0064]
Next, the first embodiment will be described in detail. The stations a to e in FIG. 3 have no master-slave relationship and operate independently as transmission apparatuses. However, in the present invention, a station that manages reference time data used for time adjustment is required, and the station a is set as the reference station. To do.
[0065]
Each of the stations a to e waits for reception of a monitoring frame from an adjacent station after performing its own internal initialization after being activated. The monitoring frame is used to grasp the loop transmission path subscription status of the local station and the adjacent station, and it is determined that the local station has successfully joined the loop transmission path by receiving the monitoring frame from another station.
[0066]
First, the operation of station a, which is the reference station, will be described.
[0067]
Since station a is a reference station having a loop reference time, it can immediately transmit a monitoring frame after activation. The transmission period of the monitoring frame is set in advance as a constant of the loop transmission system and is generated by an internal timer of the station.
[0068]
When the internal timer expires, the first interrupt is generated, the monitoring frame generation process is started, a monitoring frame is generated including the current time and failure information, and the local station transmission / retransmission relay is performed via the frame transmission driver. After confirming that it does not exist, send it to the transmission line. The monitoring frame transmitted to the transmission path is received by the adjacent stations (stations b and e in FIG. 3) via the transmission path.
[0069]
When reception data is generated in the adjacent station, a reception data input process is activated by a second interrupt, and reception data verification / capture processing is performed. At this time, if the received data is a monitoring frame, the internal time of the own station is adjusted based on the time field TF value.
[0070]
The time required for time correction is from the generation of the first interrupt of the reference station to the internal time adjustment of the adjacent station, and is divided as follows by processing blocks.
[0071]
1) Interrupt acceptance waiting time from the first interrupt generation to the start of the monitoring frame generation process
2) Monitoring frame generation time
3) Monitoring frame transmission waiting time
4) Monitoring frame transmission time
5) Interrupt acceptance wait time from the second interrupt occurrence to the start of received data input process
6) Received data verification time
The time required for 2) and 6) above is the software processing execution time, and can be calculated as a fixed value by calculation or actual measurement. 4) can also be calculated as a fixed value from the transmission rate and the size of the monitoring frame.
[0072]
On the other hand, in 1) and 5), the execution time of other interrupt processing is the maximum waiting time, and the time width varies depending on the timing. The error can be minimized by reducing the priority of the first interrupt and the second interrupt to be higher than those of other interrupts.
[0073]
3) is the time that is waited when the previous transmission frame is being transmitted or when the received data from the upstream adjacent station is being retransmitted at the time of transmitting the monitoring frame using the frame transmission driver. Yes, this required time varies greatly depending on the transmission rate and the maximum frame size.
[0074]
Assuming that the maximum frame size is 1024 bytes, the required time at each transmission rate is as follows.
[0075]
600 bps: 13.65 seconds (1 byte transmission time (13.33 milliseconds) x 1024)
2400 bps: 3.41 seconds (1 byte transmission time (3.33 milliseconds) x 1024)
9600 bps: 0.85 seconds (1 byte transmission time (0.83 milliseconds) x 1024)
28800 bps: 0.28 seconds (1 byte transmission time (0.27 milliseconds) x 1024)
At the time of actual system construction, the maximum frame size is determined by suppressing the maximum transmission time of one frame to about 1 to 2 seconds. Therefore, the above delay time is not necessarily obtained, but the TF value is used when there is a deviation of second order. There is a possibility that illegal frame discard processing may malfunction, and it is not suitable for time correction.
[0076]
As a countermeasure, a correction permission bit is provided in the MSB of the time field TF value of the monitoring frame, and when the above-mentioned 3) is waiting for transmission, the correction permission bit is turned off and then saved in the transmission waiting buffer. The time correction process on the receiving station side is not activated.
[0077]
Stations other than the reference station receive monitoring frames from adjacent stations and complete the time adjustment to enable frame transmission from their own stations. Thereafter, as with the reference station, transmission of monitoring frames to other stations adjacent to the own station is specified. It will be done in a cycle. By repeating these steps, all stations connected to the loop transmission line are adjusted to the time of the reference station, and the correction is repeated at a specified period or a multiple of the specified period. Naturally, monitoring frame transmission to the reference station also occurs. However, the reference station does not perform any time correction using the monitoring frame received from another station, and the monitoring frame is used only for monitoring the status of the adjacent station.
[0078]
Further, since the monitoring frames are received from both the XY loops, it is assumed that there is a difference between the monitoring frame reception timing from the X loop and the monitoring frame reception timing from the Y loop at the time of initial activation. This time difference is very small considering the delay time described above, but if both of the monitoring frames received from both loops are used for time correction, the later-arrived monitoring frame will always be effective, eliminating the shift width. Hateful.
[0079]
Therefore, when the TF value of the monitoring frame received from the local station time is large, the local station time is adjusted to the TF value, and the local station and the adjacent station repeat periodic fine corrections to minimize the deviation width. Turn into.
[0080]
Next, a description will be given of stations b to e that do not have a reference time.
[0081]
Since the stations b to e in FIG. 3 are not set as the reference station, after the start-up, the specified time waits for the reception of the monitoring frame from the adjacent station, and the time of the own station is adjusted by receiving the monitoring frame. When the time adjustment is completed, transmission of the monitoring frame to both adjacent stations connected to the XY loop is started at the specified monitoring frame transmission cycle as in the reference station.
[0082]
The monitoring frame reception waiting time from the adjacent station after activation is set to 3 times the monitoring frame transmission cycle. If the monitoring frame is not received within that time, it is activated first in the loop or the reference station is down The monitoring frame is transmitted to both adjacent stations with the count value from the initial value 64 to 127 different from the time value as the TF value. Thereafter, a monitoring frame is received from an adjacent station, and if the TF value is a time value from 0 to 59, the time is unconditionally adjusted, and if it is not a time value, the time correction described above in the range of 64 to 127 is performed. Process.
[0083]
Next, the time required for all stations connected to the loop to complete time correction will be described.
[0084]
When the stations a to e in FIG. 3 are activated all at once, a monitoring frame is first transmitted from the station a which is the reference station. Since transmission is performed simultaneously in both XY loops, it can be transmitted simultaneously from the X loop side to station b and from the Y loop side to station e.
[0085]
Assuming that the monitoring frame transmission cycle is 3 seconds, the time correction completion for stations b and e is 3 seconds after the maximum. Since station b and station e have completed their time correction, station b transmits a monitoring frame to stations c and a, and station e transmits to stations d and a in the next 3 seconds.
[0086]
From these, the time required for time correction is expressed by the following calculation formula. When 31 stations with the maximum configuration are connected to the loop, the correction is completed in 45 seconds.
[0087]
(Total number of stations-1) / 2 x 3 seconds = Time required to complete time correction for all stations
However, when a loop transmission system is operated, the stations are located far away from each other, so simultaneous activation does not actually occur, and each time one station is individually activated, it joins the loop. It is common to take the form.
[0088]
In this case, assuming that the station that has joined the loop has completed time correction before joining the own station, the time correction is completed within 3 seconds after newly joining the loop.
[0089]
(Second Embodiment)
In the second embodiment, the following configuration is added to the basic configuration described above. That is, each transmission apparatus includes an internal counter in addition to the above-described frame transmission system and frame reception system. Each internal counter has a count value representing a time interval in a transmission frame, and has a function of correcting the internal counter of the own station from count data in a frame received from another transmission device in the loop.
[0090]
A count value of 0 to 127 is set in TF during the monitoring frame. This count value has an initial value of 0, and increments by a prescribed time unit, and increments from 127 to 0.
[0091]
This count value is not related to the time (time signal), and the stations connected to the loop adjust each other. For this reason, there is no reference station as described in the first embodiment.
[0092]
A station that has received a monitoring frame adjusts its own count value to the TF value in the monitoring frame when the time field TF value in the monitoring frame is larger than the count value of its own management, and the transmission period of the monitoring frame is also this. Tune in.
[0093]
According to the second embodiment, the operation of synchronizing the count value step timing and the monitoring frame transmission timing of all the stations connected to the loop can easily and accurately discard the illegal frame using the time field TF, Transmission efficiency can be improved.
[0094]
Next, details of the second embodiment will be described.
[0095]
In the first embodiment, there is a reference station having time data serving as a reference, but in this embodiment, there is no reference station. The numerical value adopted for the time field TF value is a count value from the initial value 0 to 127.
[0096]
The correction method of the count value is the same as that of the first embodiment, and the time and accuracy required for the initial correction are the same as those of the first embodiment, but mutual correction is performed between stations without having a reference station. The variation in the count width in unit time has a feature that it is accumulated without being corrected.
[0097]
Compared to the first embodiment, the advantage of this embodiment is that a system can be easily constructed because a reference station is not necessary, and the width of the time field TF value is widened, so that more accurate illegal frames can be discarded. There are two points.
[0098]
The time field TF value for determining a normal frame is
Assuming (local station count value <reception TF value <local station count value + 7),
In the first embodiment, 60 widths from 0 to 59, or 64 widths from 64 to 127 are valid values, and data width 7 is normally handled, so the detection probability of an illegal frame is as follows.
[0099]
(1-7 / 60 (or 64)) × 100 = 88 (89)%
In the second embodiment, the width is 128 from 0 to 127, and the data width 7 is normally handled.
(1-7 / 128) × 100 = 95%
Is the detection probability of an illegal frame.
[0100]
(Third embodiment)
In the third embodiment, the following configuration is added to the basic configuration described above. In the first or second embodiment, having a function of obtaining a transmission load in time units described later based on time data or count data in a frame transmitted / received by each transmission apparatus and the size of the transmission frame It is.
[0101]
Each station connected to the transmission path has a table for storing the number of transmission bytes divided by a specified time, and the index used for referring to this table is the time or count value in the own station.
[0102]
When data transmission occurs, the number of transmission bytes stored at the address of the recording medium with the internal time or count value as an index is added. The maximum number of bytes that can be transmitted within the specified time range is determined by the transmission speed, and the total number of frame bytes transmitted within the specified time is divided by the maximum number of bytes to determine the transmission load [actual value for maximum transmittable capacity (or time). Ratio of transmission capacity (or time)].
[0103]
In the third embodiment, it is possible to investigate the transmission load in various periods such as second / separation / hourly / weekly / monthly by changing the setting of the specified time as an index of the table.
[0104]
Here, if the transmission load is expressed in another form, it can be expressed as follows.
[0105]
Transmission load (%) = Number of bytes transmitted / Number of bytes that can be transmitted within the specified time
Next, the third embodiment will be described in detail. In this embodiment, the following configuration is added to the first or second embodiment.
[0106]
Each station connected to the transmission path has the transmission byte count storage table of FIG. 6 in the recording medium 13 of FIG.
[0107]
There are two types of transmission data: local station transmission and retransmission relay, and reception data: local frame reception (including broadcast frames) and other station reception frame reception. Since the reception of frames addressed to other stations always has the same value, here, the integrated trace is performed with three types of the number of data transmitted from the local station, the number of received data of the frame addressed to the local station, and the number of retransmission relay data.
[0108]
The total number of bytes in the transmission byte count storage table is updated by the frame transmission driver and the frame reception driver, respectively. In retransmission relay, the frame reception driver is used when determining the frame addressed to another station.
[0109]
The difference between the case where the first embodiment is used and the case where the second embodiment is used is the difference in time data used for the time axis index.
[0110]
In the first embodiment, since the time value is used as a time axis index, an integrated trace relative to the time signal can be performed, the transmission load in the time zone can be grasped, and an external event can be associated with the transmission load.
[0111]
Here, for example, when the transmission load in the case where the specified time = 1 minute (60 sec), the number of transmitted bytes = 800 bytes, and the transmission speed = 9600 bps is obtained, it is as follows.
[0112]
800 bytes / (9600 bps / 8 bits) × 60 sec = 0.011 (1.1%), and the transmission load is about 1%. If a large amount of external events (events and device operations) occur, transmission information increases accordingly and the transmission load increases. If the transmission load rises above a certain value, information communication between transmission devices may be stagnant or transmission data may be lost, affecting the entire system. As analysis data in such a situation, by dividing the time axis by a specific width and storing the transmission load in each time zone, grasp the change (increase / decrease) in the transmission load on the time axis as statistical information become able to. Since an external event is usually printed in a separate device as a log of the occurrence (operation) time, it is easy to link to a transmission load change time zone.
[0113]
In contrast, in the second embodiment, since the count value is used as a time axis index, it becomes an integrated trace from the start of the trace and the transmission load in the time zone can be grasped. It cannot be associated.
[0114]
In this case, a terminal device having time data is connected to the transmission apparatus, and the integrated trace can be picked up from time to time, and a time index can be associated with an external event.
[0115]
(Fourth embodiment)
In the fourth embodiment, the following configuration is added to the first or second embodiment described above. In other words, the failure status data of the own transmission device is included in the transmission frame, and the failure of the transmission device and the transmission path adjacent to the own transmission device is determined from the failure status data of the transmission device in the frame received from another transmission device belonging to the loop It has a function of grasping the state and a function of detecting a failure of the own transmission apparatus and transmission path that cannot be detected from the own transmission apparatus.
[0116]
In this case, the failure status information of the own station is set in the monitoring frame and transmitted to both adjacent stations of the X and Y loops, and the adjacent station that has received the information recognizes the failure status of the own station.
[0117]
In the fourth embodiment, the failure detected by the own station is communicated to the adjacent station, so that it is possible to recognize the cause failure of the own station that cannot be detected only by the own station and to identify the failed part in the loop transmission system.
[0118]
Next, the fourth embodiment will be described in detail. In this embodiment, in addition to the first or second embodiment, the following configuration is provided.
[0119]
As shown in FIG. 2, the transmission apparatus is composed of a plurality of modules, and among them, failure of the transmission path 2 and the modems 19 and 20 often cannot be detected only by self-diagnosis.
[0120]
In order to improve this, failure information is attached in the format shown in FIG.
[0121]
Assume that the X-loop direction of the transmission path between the stations b and c fails in the configuration of FIG.
[0122]
The station c detects carrier-off, reception data abnormality, monitoring frame reception timeout, and the like from the X direction reception line side. As a result, station c is listed as a failure point in two points: a failure in the transmission path and a failure in station b itself.
[0123]
Also, since the a-b station is normal, the a station does not detect any failure. Transmission from station b to station c cannot be performed, but transmission from station c to station b in the Y loop direction can be performed. Therefore, failure information detected by station c is set in a monitoring frame and notified to station b. . Then, the station b can detect that the line in the X direction loop has failed based on the failure information of the monitoring frame received from the station c.
[0124]
Further, when the station b itself is down, the stations a and c detect the monitoring frame reception timeout, and therefore it can be determined that the station b is down.
[0125]
(Fifth embodiment)
In the fifth embodiment, the following configuration is added to the above-described fourth embodiment. In other words, it has a function of integrating failure detection / recovery information detected by the own station and failure occurrence recovery information received from adjacent stations in units of time, obtaining statistics, and determining the frequency of failure occurrence in units of time.
[0126]
The failure occurrence return change is recognized from the failure information of the own station and the adjacent station described in the fourth embodiment, and they are integrated in time units described in the third embodiment. The unit time is divided by a certain width based on the time value and the count value after time correction described in the first or second embodiment.
[0127]
In the fifth embodiment, it is possible to grasp a change in failure occurrence frequency with time by integrating statistics of each failure occurrence return in time series. Further, by comparing and examining this with an external event, it becomes possible to identify the cause of failure at an early stage and to prevent failure.
[0128]
Next, the fifth embodiment will be described in detail. In this embodiment, in addition to the fourth embodiment, the transmission byte count storage table of FIG. 6 described in the third embodiment has the same configuration.
[0129]
As shown in the failure detection count storage table in FIG. 7, the failure target items include the number of times of monitoring frame reception timeout, the CS signal (Clear to Send: a signal indicating transmission permission notified from the modem), the number of OFF detections, the CD signal ( (Carrier Detect: signal indicating the reception carrier state notified from the modem) This is the fifth type of OFF detection count, abnormal frame reception count, and frame discard count based on the time field TF value.
[0130]
This includes a failure detected by the own station and a failure detected by an adjacent station and notified by a monitoring frame, but no special distinction is made in this embodiment.
[0131]
The monitoring frame received from the adjacent station is notified to the transmission path monitoring process via the frame receiving process. Also, the failure information detected by the own station is finally notified to the transmission path monitoring process and processed.
[0132]
The table shown in FIG. 7 has two XY loops, and the update timing of the table is when a failure occurrence / recovery is detected based on the time axis index, and is as follows.
[0133]
The monitoring frame reception time-out count starts a timer for three times the transmission period when a monitoring frame is received in the transmission line monitoring process, detects that a failure has occurred when the timer expires, and monitors again before the timer expires When a frame is received, the activated timer is reset and restarted, and when a monitoring frame is received after the occurrence of a failure, failure recovery is detected.
[0134]
The CS signal OFF detection count is an interrupt that occurs when the CS signal changes. If the CS signal is OFF, the CS signal is detected as a failure occurrence.
[0135]
The CD signal OFF detection count is an interrupt that occurs when the CD signal changes. If the CD signal is OFF, it is detected as a failure occurrence, and if the CD signal is ON after a subsequent interruption, it is detected as a failure recovery.
[0136]
The number of abnormal frame receptions is detected by the frame reception process, and is counted up for each detection without occurrence recovery.
[0137]
The number of frame discards based on the time field TF value is detected by the frame reception process, and is not incremented and is counted up for each detection.
[0138]
【The invention's effect】
According to the present invention described above, the following effects can be obtained.
[0139]
(1) Loop type data that provides means for discarding, for example, illegal frames by tuning between independent transmission apparatuses, and as a result, N: N data transmission is possible, and transmission efficiency can be greatly improved compared to conventional transmission systems. A transmission system can be provided.
[0140]
(2) By carrying out transmission path load monitoring and adjacent station monitoring proactively, it is possible to prevent failures before they occur, early detection of failure occurrences, and identification of failure locations, making loop data transmission systems more reliable. Can be provided.
[Brief description of the drawings]
FIG. 1 is a diagram showing a basic configuration example of a loop type data transmission system according to the present invention.
2 is a hardware configuration diagram for explaining a specific example of each transmission apparatus in FIG. 1;
3 is a diagram showing a connection configuration of the transmission line in FIG. 1;
FIG. 4 is a diagram showing a configuration of a transmission frame in a loop type data transmission system according to the present invention.
5 is a diagram showing a configuration of a destination address field DA in FIG. 4. FIG.
FIG. 6 is a diagram for explaining a transmission byte count storage table.
FIG. 7 is a diagram for explaining a failure detection frequency storage table;
FIG. 8 is a configuration diagram of a conventional SDLC loop data transmission system.
9 is a configuration diagram of a frame used in the conventional loop type data transmission system of FIG.
10 is a frame transmission time chart for explaining a frame transmission state in the conventional loop type data transmission system of FIG.
[Explanation of symbols]
1 Center transmission device
2 ... Transmission path
3 ... Transmission device
5 ... Personal computer
6 ... Station control device
11 ... MPU
12 ... Bus line
13. Recording medium
15-18 ... Serial interface
19, 20 ... modem

Claims (8)

In a loop type data transmission system in which a plurality of transmission devices are connected in a loop via a transmission line,
Each transmission device includes a frame transmission system, a frame reception system, and an internal clock, and when the frame transmission system receives a data transmission request from the outside, a destination address field and a transmission source address field are provided on the head side. Creating the provided frame and sending it to the transmission line,
Time data used for determining an illegal frame is placed near the beginning of the frame, and when the frame is received, the frame reception system determines whether the received frame is correct or not before the reception of all one block of the received frame is completed . The destination address and the source address are compared with the own address, and when any address does not match the own address, the received frame is relayed to the downstream device, and when any address matches the own address, the received frame Is removed from the transmission line,
The internal clock sets the time data of its own transmission device in the transmission frame, and corrects the internal clock of its own transmission device from the time data in the received frame when a frame is received from an adjacent transmission device in the loop. And a loop type data transmission system having a function of synchronizing the time of each transmission device. In a loop type data transmission system in which a plurality of transmission devices are connected in a loop via a transmission line,
Each transmission device includes a frame transmission system, a frame reception system, and an internal counter,
When the frame transmission system receives a data transmission request from the outside, the frame transmission system creates a frame provided with a destination address field and a transmission source address field on the head side and transmits the frame to the transmission path,
Time data used for determining an illegal frame is placed near the beginning of the frame, and the frame receiving system performs a correct / incorrect determination on the received frame before receiving all one block of the received frame when receiving the frame. The destination address and source address of the field are compared with the own address, and when any address does not match the own address, the received frame is relayed to the downstream device, and when any address matches the own address Removing the received frame from the transmission path;
The internal counter has a count value representing a time interval in a transmission frame, and has a function of correcting the internal counter of the own station from count data in a frame received from another transmission device in the loop. Type data transmission system. In a loop type data transmission system in which a plurality of transmission devices are connected in a loop via a transmission line,
Each of the transmission devices includes a frame transmission system, a frame reception system, and an internal clock. The frame transmission system receives a data transmission request from the outside, and a destination address field provided on the head side and a head side A time field for disposing of illegal frames to be provided and a time field for time correction, and a frame provided with a source address field are created and transmitted to the transmission path,
Time data used for determining an illegal frame is placed near the beginning of the frame, and the frame receiving system performs a correct / incorrect determination on the received frame before receiving all one block of the received frame when receiving the frame. The destination address and source address of the field are compared with the own address, and when any address does not match the own address, the received frame is relayed to the downstream device, and when any address matches the own address Removing the received frame from the transmission path;
The internal clock sets the time data of its own transmission device in the transmission frame, and corrects the internal clock of its own transmission device from the time data in the received frame when a frame is received from an adjacent transmission device in the loop. And a loop type data transmission system having a function of synchronizing the time of each transmission device. In a loop type data transmission system in which a plurality of transmission devices are connected in a loop via a transmission line,
Each transmission device includes a frame transmission system, a frame reception system, and an internal counter,
When the frame transmission system receives a data transmission request from the outside, the frame transmission system includes a destination address field provided on the head side, a time field for illegal frame discard and time correction provided on the head side, and a frame provided with a source address field. To create and send to the transmission line,
Time data used for determining an illegal frame is placed near the beginning of the frame, and the frame receiving system performs a correct / incorrect determination on the received frame before receiving all one block of the received frame when receiving the frame. The destination address and source address of the field are compared with the own address, and when any address does not match the own address, the received frame is relayed to the downstream device, and when any address matches the own address Removing the received frame from the transmission path;
The internal counter has a count value representing a time interval in a transmission frame, and has a function of correcting the internal counter of the own station from count data in a frame received from another transmission device in the loop. Type data transmission system. Each transmission device adds to the transmission frame as a time field of the internal clock at the time of frame transmission, and the time field in the frame transmitted from the transmission station is not required to be rewritten in subsequent regenerative relaying. 5. The function according to claim 1, further comprising a function of determining the normality of the received frame based on a time difference from a time field in the received frame caused by a step of the internal time of the own apparatus. Loop type data transmission system. 5. A function of obtaining a transmission load in units of time based on time data or count data in a frame transmitted and received by each transmission device and a size of the transmission frame. The loop type data transmission system according to any one of the above. The transmission frame has failure state data of its own transmission device in the transmission frame, and from the failure state data of the transmission device in the frame received from another transmission device belonging to the loop, the failure state of the transmission device and transmission line adjacent to the transmission device 5. The loop type data transmission according to claim 1, wherein the loop type data transmission has a function of grasping an error and a function of detecting a failure of the own transmission apparatus and transmission path that cannot be detected from the own transmission apparatus. system. 8. The function according to claim 7, which has a function of integrating failure detection / recovery information detected by the own station and failure occurrence recovery information received from an adjacent station in units of time, taking statistics, and determining a frequency of failure occurrence in units of time. Loop type data transmission system.

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