JPS6013626B2 - Abnormal part location method for common transmission line - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a system in which a plurality of stations are branch-connected to at least one set of common transmission channels, and data transmission between the stations is performed between arbitrary mutual stations via this common transmission path. In a data highway system, when an abnormality such as a disconnection occurs in the common transmission line, the abnormal transmission line can be automatically removed and the system can continue to operate using the remaining normal transmission line. The present invention relates to a method for determining abnormality occurring in a common transmission line, and in particular to a method for identifying an abnormality occurring part of a common transmission line.

For example, as shown in FIG.
In a data highway system in which stations 3-n and 3-n are branched, assuming that the point indicated by the X rule on common transmission line 1 is cut off, common transmission line 1 is divided into two, so stations 3-1 and 3-n are Not only is data transmission between the other stations 3-2 to 3-n impossible, but one end of the bisected common transmission line cannot be matched, causing a reflection phenomenon during transmission. occurs, making normal data transmission impossible.

For this purpose, as shown in FIG.
A method of branching and connecting stations 3-1 to 3-n to station 1-2 has been adopted, but this requires two sets of common transmission lines (cables), and two sets of receivers/drivers must be prepared or the transmission line It is necessary to prepare a conversion circuit, which inevitably results in an expensive system.

Another solution is to loop the common transmission path 1 as shown in Figure 3, and when the common transmission path is disconnected, stations on both sides of the disconnection point among stations 3-1 to 3-n are terminals. Although a method for continuous operation as a station has been adopted, the transmission speed (KBit/
Since the product of S) and cable length (object) is required to be several K (kilometers) or less, there is a limit to its application. It is not applicable to the required system.

Therefore, in order to keep the system price low, the applicant proposed that there be one set of common transmission lines, and that even if this common transmission line is disconnected, automatic continuous operation will be performed with both ends removed. We have separately discussed possible common transmission line configuration methods.

The principle and embodiments of this separate proposal will be explained below with reference to the drawings.

Figure 4 shows an example of the configuration of each station, 4a,
4b is a switch that controls the termination of the transmission line, 5a, 5b
6 is a terminal resistor of the W transmission line, 6 is a receiver driver for coupling the stations to the common transmission line, and 7a and 7b are terminals for connecting the transmission line. If there is no need to take the last station at the station in question, switches 4a and 4b are set to the fourth position.
In the position shown in the figure, the transmission line connected to the terminals 7a and 7b is directly connected, and the receiver driver 6 is branch-coupled to the transmission line.

If it is necessary to terminate the transmission line at the station, the switch 4a remains in the position shown in FIG. 4, and the switch 4b is switched to the terminating resistor 5b side. Conversely, if you want to terminate the transmission line on the terminal 7b side, leave switch 4b in the position shown in Figure 4.
a is switched to the terminating resistor 5a side. The receiver/driver 6 is in each case branch-connected to the terminated transmission line. FIG. 5 shows a connection configuration in which a plurality of stations having the configuration shown in FIG. 4 are connected in a ring and the terminals are taken at station SI and station Sn.

In FIG. 5, at all stations S2 to S(n-1), switches 4a and 7b are positioned so that the transmission lines are directly connected, and stations SI and Sn have an effective common transmission line. Take a position such that the end of the plane is taken. That is, the connection configuration shown in FIG. 5 shows the configuration of the branch connection type common transmission line in FIG. 1, if the switches 4a and 4b at each station are ignored. Now, consider a case where the transmission line between stations S1 and S2 in FIG. 5 is cut off for some reason at the point marked with an x in FIG. 6. It is obvious that it is not possible to create a common transmission base that includes all of the stations SI to Sn in Figure 5), but in this case, the first transmission is carried out using the means described later in the first three defeats. *It is detected that the cut point of the track is between stations SI and S2, and station S
Switches 4a and 4b from 3 to Sn are placed in positions where the transmission lines are directly connected, and at station SI, 4a is placed in a position where it is directly connected, and 4b is placed in a position where it is connected directly to the terminating resistor 5b. In S2, 4b is placed in a position where it is directly connected, and 4a is placed in a position where it is exposed to the terminal resistor 5a. FIG. 6 shows the connection configuration after system reconfiguration. As is clear from Fig. 6, the cut transmission line between station SI and station S2 has no relation to the configuration of the re-established common transmission line, and the normal common transmission line with both ends is I can see that it has been achieved. According to the above-mentioned method, a terminating resistor and a changeover switch are installed at each station, the terminating resistor is configured to be able to be used selectively at each station, and the transmission line between each station is routed around all the stations. By connecting them in the same way, even if one transmission line is cut off, a common transmission line with both ends removed can be configured using one set of common transmission lines, so even if a transmission line is cut off, the system will not go down. It is possible to configure a common transmission path for data/way that does not occur.

FIG. 7 shows an example of a detailed configuration of each station shown in FIG. 4, in which a circuit for determining a disconnected transmission line and a switch control circuit after the determination are added to FIG. 4.

Now, consider a case in which an abnormality such as a disconnection occurs in the transmission line between stations SI and Sn in FIG. First, it is necessary for all stations or both stations to which the transmission line is connected to identify the abnormal transmission line. The present invention provides a locating method for this identification.

To explain the method for this, all stations constantly monitor the data transmission status of the common transmission line, so if a transmission line abnormality such as a disconnection occurs, for example, a change in the transmission signal width or a change in the check data of the data frame is detected. etc., an abnormality in the transmission line can be recognized within a few degrees S to several degrees S. All stations then locate the abnormal transmission line. In orientation mode 1, switch 4a in FIG. 7 is operated, and switch 4
Furthermore, the terminating resistor 5b is connected to the transmission line on the 7a side, and the receiver/driver 6 transmits diagnostic data to check the status of the transmission line on the 7b side by the receiver driver 6. Monitor. This connection state is Si-1 to Si-11.
FIG. 9 shows the station. At this time, if there is an abnormality such as a disconnection in the transmission line, "1" is set in the memory section 8a in FIG. 7 (if there is no abnormality, it is set to "0").
(noma) is). In the Erizada mode, "Return the switch 4a in Figure 7 and operate the switch 4b in reverse to connect the terminating resistor 5b to the transmission line on the 7a side via the switch 4a, and then connect the terminating resistor 5a to the transmission line on the 7b side. The diagnostic data is transmitted from the receiver/driver 6, and the state of the transmission line on the side 7a is monitored by the receiver/driver 6.The subsequent state is shown in FIG. 10 in correspondence with FIG. At this time, if there is an abnormality such as a disconnection in the transmission line, "1" is set in the register section 8b in Fig. 7 (if there is no abnormality, it remains "0").The method for setting the memory section is In Fig. 7, for convenience, it is shown that the seater/driver 6 is set as shown by the dotted line, but this method can be implemented arbitrarily.After executing orientation modes 1 and n,
Each station executes a reconfiguration mode in which the switches 4a and 4b are operated to reconfigure the common transmission path.

In the reconstruction mode, each station utilizes the results in the storage units 8a and 8b determined in the orientation modes 1 and n. That is, when the memory section 8a is "1", the switch 4a
When the memory section 8b is "1", the switch 4b is activated.
make it work. In Fig. 5, stations SI and S2
Since an abnormality has occurred in the transmission line between
is set to "1", and "1" is not set to either the storage units 8a or 8b at any other station.

Looking at FIG. 6 again from this point of view, FIG. 6 shows switch 4b of station SI and switch 4 of station S2.
a operates, and switches 4a and 4 of other stations
b indicates a connection configuration in which none of the connections is in operation. FIG. 6 shows that the transmission line between stations SI and S2 (the transmission line where the abnormality occurred) has been removed, and the stations SI to Sn are finally branched and connected. That is, when an abnormality such as a disconnection occurs in the common transmission path, each station detects the abnormality and automatically realizes the reconfiguration of the common transmission path through determination mode 1 → orientation mode 0 → reconfiguration mode. The above is a case where a disconnection point occurs in the common transmission line, but if there is no abnormality such as disconnection anywhere on the transmission line, such as when starting up the system, the above reconfiguration operation will be repeated indefinitely. there is a possibility.

Measures to deal with this will be explained below. FIG. 8 shows the switch 4a connecting the terminal 7a and the terminating resistor 5b in FIG.
c, a switch 4b that connects the terminal 7b and the terminal resistor 5a.
This is the case when 4d is changed.

The switches 4c and 4d are individually selectable between manual and automatic, and when set to automatic, the operation is exactly the same as that shown in Fig. 7.
In other words, it performs exactly the same operation as 4a. If set to manual, it will not operate, that is, it will remain open. When starting up a system by connecting stations configured in this way in a ring as shown in Figure 5, the common transmission path can be activated by manually turning switch 4c or 4d on any one station to start up the system. can be easily understood from the above explanation. After the system is started, if the switch 4c or 4d, which was previously set to manual, is returned to automatic, there will be no problem in reconfiguring the common transmission line even if an abnormality such as a disconnection occurs in the transmission line. In addition, although the case where one receiver/driver 6 is prepared has been explained so far, it is also possible to use two receivers/drivers.

In Figure 11, the receiver/drivers 6a and 6b are connected to the terminating resistor 5.
An example is shown in which A and 5B are connected in parallel. In location mode 1 with this configuration, the switches 4a and 4b are connected to the terminating resistors 5a and 5b, and, for example, the receiver/driver 6a transmits diagnostic data to the adjacent station, and the receiver/driver 6a transmits diagnostic data to the adjacent station. driver 6b
receives diagnostic data. If there is an abnormality such as a disconnection in the transmission line, the diagnostic gate data will not be received at all or incorrect data will be received, so it is possible to determine whether the transmission line is abnormal. At the transmitting station, in orientation mode 1, it is possible to determine whether there is an abnormality in the transmission line using the method described above. Receive diagnostic data and determine abnormalities in the transmission line. According to the present invention, a terminating resistor and a changeover switch are installed at each station, and when an abnormality is detected in the common transmission line, a double-terminated transmission line can be automatically configured between two adjacent stations. In this way, diagnostic data from the own station or other stations can be monitored, so that in the event of an abnormality in the common transmission line, the stations on both sides to which the transmission line is connected can reliably connect the transmission line where the abnormality such as disconnection has occurred. It became possible to locate.

Moreover, all of this orientation operation can be done automatically. In addition to the common transmission line of the data highway described above, this invention also applies when the common transmission line is composed of multiple cables, when the common transmission line is multiplexed, and when the common transmission line is short. (for example, a common transmission path between devices). Furthermore, if the transmission line connecting each station does not go around, it goes without saying that two sets of common transmission lines with both ends can be reconfigured.

1, 2 and 3 are block diagrams showing an example of the configuration of a conventional common transmission system, FIG. 4 is a circuit diagram of an example of the station configuration according to the present invention, and FIG. 6 and 6 are circuit diagrams showing major switching states before and after the occurrence of an abnormality at multiple stations, FIG. 7 is a more detailed circuit diagram of FIG. 4, and FIG. 8 is a modified example of the circuit in FIG. 7. 9 and 10 are circuit diagrams for explaining the constant mode of the abnormality occurring portion, and FIG. 11 is a circuit diagram of a modification of the circuit in FIG. 7.

SI~Si-1, Si, Si11~Sn. ．． 、． ．． ．． Station, 1, li-1, li, li+1...
・Transmission line, 4a, 4b, 4c, 4d...switch switch,
5a, 5b...Terminal resistor, 6, 6a, 6b...
...Receiver/driver. Oh figure, figure 2 figure, figure o 3 figure, figure 4 figure figure, figure figure, figure figure, figure figure, figure figure, figure figure, figure figure, figure figure, figure figure, figure figure, figure figure, figure figure, figure figure, figure figure, figure figure, figure figure, figure figure, figure figure 2, figure figure 2, figure figure 3, figure figure 4, figure figure figure figure.

Claims (1)

[Claims] 1. In a data transmission system in which a plurality of stations are branch-connected to at least one set of common transmission paths, and data transmission between the stations is performed between arbitrary stations via this common transmission path. , a receiver/driver, a termination unit, and a switching means are provided for each station, and when an abnormality is detected in the transmission path, each station simultaneously and automatically switches to execute the next orientation mode I and II in sequence. An abnormality location method for a common transmission line characterized by switching means. (Location mode I) Viewed in the direction along the common transmission line, connect the termination unit to one side of the transmission line for each station, connect the receiver/driver to the other side of the transmission line, and perform diagnosis using the receiver/driver. Sends data and detects whether there is an abnormality in the transmission path. (Location mode II) When viewed in the direction along the common transmission path, for each station, connect the termination unit to the transmission path on the other side, connect the receiver/driver to the transmission path on one side, and connect the receiver/driver to the transmission path on the other side. Sends diagnostic data to detect whether there is an abnormality in the transmission path.