JPS6013625B2 - Common transmission path configuration method - 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 paths, and data transmission between the stations is performed between arbitrary stations via this common transmission path. In a data highway system, when an abnormality such as a disconnection occurs in a common transmission line, the abnormal transmission line section is automatically removed and the remaining normal transmission line section is used to maintain continuous operation of the system. Regarding the method that makes it possible.

For example, as shown in FIG.
A plurality of stations 3 are connected to a common transmission path 1 terminated by
In a data highway system in which -1 to 31n are connected skin-to-skin, if we assume that the point indicated by the cross on the common transmission line 1 is cut off, the common transmission line 1 will be divided into two, so
Station 3-1 and other stations 3-2 to 3-n
Not only will data transmission between the becomes.

For this purpose, as shown in FIG. 2, the common transmission lines are duplicated, and each common transmission line 1-
A method is adopted in which stations 3-1 to 3-n are branch-connected to 1, 1-2, but two sets of common transmission paths (cables) are required, and two sets of receivers/drivers are also prepared or the transmission It is necessary to prepare a circuit for cutting the road,
This inevitably results in an expensive system. Another solution is to loop the common transmission line 1 as shown in Figure 3, and when the common transmission line is disconnected, station 3
Among 11 to 3-n, a method has been adopted in which both stations at the disconnection point are used as terminal stations to ensure continuous operation, but in this type of circular transmission line, as a condition for reliable data transmission, Since the product of speed (KBit'S) and cable length (ship) is required to be less than several K (kilometers), there is a limit to its application. Mega) is also inapplicable to systems that require it.

Therefore, in order to reduce the cost of the system, the present invention uses one set of common transmission lines, and even if this common transmission line is disconnected, it is possible to automatically continue operation with both ends removed. The purpose is to provide a possible configuration method for a common transmission path.

The principle and embodiments of the present invention 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
1 is a terminating resistor representing a terminating unit of a transmission line, 6 is a receiver driver for coupling stations to a common transmission line, and 7a and 7b are terminals for connecting the transmission line.
If there is no need to terminate at the station, switches 4a and 4b are in the position shown in Figure 4, the transmission lines connected to terminals 7a and 7b are directly connected, and the receiver/driver 6 is connected to the transmission line base. The husband M neighbors are connected to each other.

If it is necessary to terminate the transmission line on the terminal 7a side at that 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, when the transmission line is terminated on the terminal 7b side, the switch 4b remains in the position shown in FIG. 4 and the switch 4a 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 station SI and station Sn.
In FIG. 5, at all stations S2 to S(n-1), switches 4a and 4b are positioned so that transmission lines are directly connected, and stations SI and Sn have an effective common transmission line. Take a position such that the end of 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 station SI and station 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 construct a common transmission line that includes all of the stations SI to Sn with the state shown in FIG.
Switches 4a and 4b from stations S3 to Sn are set to positions where the transmission lines are directly connected, and at station SI, 4a is connected to the terminating resistor 5b, and 4b is connected to the terminating resistor 5b. At station S2, 4b is placed in a position where it is directly connected, and 4a is placed in a position where it is connected to the terminating resistor 5a. FIG. 6 shows the connection configuration after system reconfiguration. As is clear from Figure 6, the disconnected transmission line between station SI and station S2 has no relation to the configuration of the reconfigured common transmission line, and a normal common transmission line with both ends terminated was realized. I understand that. According to the present invention, a terminal resistor and a switch are installed at each station, and each station is configured to be able to selectively use the terminal resistor.
Furthermore, by following the transmission line between each station so that it goes around all the stations, one set of common transmission lines ensures that even if one point on the Denbodo line is cut off, both terminals are always connected. Since the transmission line can be constructed, it is possible to construct a common transmission line for the data highway that will not cause a system down even if the transmission line is cut.

FIG. 7 shows an example of the detailed configuration of each station shown in FIG. 4, in which a circuit for determining the cut key path 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 stations on both sides to which the transmission line is connected to identify the abnormal transmission line. To explain the method for this, all stations constantly monitor the data transmission status of the common transmission line, so when an abnormality in the transmission line such as a disconnection occurs, the abnormality in the transmission line is recognized within several rs to several ms. do. All stations then locate the abnormal transmission line. In the orientation mode i, the switch 4a in FIG. 7 is operated, the terminating resistor 5a is connected to the transmission line on the 7b side via the switch 4b, the terminating resistor 5b is further connected to the transmission line on the 7a side, and the receiver node is connected. Diagnostic data is transmitted from the driver 6, and the state of the transmission line on the 7b side is monitored by the receiver driver 6. FIG. 9 shows this connection state for stations Si-1 to Si+1. At this time, if there is an abnormality such as a disconnection in the transmission line, "1" is set in the storage section 8a in FIG. 7 (if there is no abnormality, it remains at "0"). In the orientation mode h, the switch 4a in FIG.
The diagnostic data is transmitted from the receiver driver 6 by connecting to the transmission line on the side 7a, and the condition of the transmission line on the side 7a is monitored by the receiver driver 6. This tangential rut state is shown in FIG. 10 in correspondence with FIG. 9. At this time, if there is an abnormality such as a disconnection in the transmission line, "1" is stored in the storage section 8b in FIG.
Set (remains “0” when there is no abnormality)
. For convenience, FIG. 7 shows how to set the storage section by setting it from the seat drive driver 6 as shown by dotted lines, but this method can be implemented arbitrarily. After executing orientation modes i and U, each station switches to switch 4a.
and 4b to execute a reconfiguration mode for reconfiguring the common transmission path.

In the reestablishment mode, each station utilizes the results in the storage units 8a and 8b determined in the reestablishment modes i and ii. 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 perspective, FIG. 6 shows a connection configuration in which the switch 4b of station SI and the switch 4a of station S2 are operated, and the switches 4a and 4b of the other stations are not operated. There will be. FIG. 6 shows that stations SI to Sn are branch-connected to a common transmission line from which the transmission line between stations SI and S2 (the transmission line where the abnormality occurred) has been removed. That is, when an abnormality such as a disconnection occurs in the common transmission path, each station detects the abnormality and automatically realizes reconfiguration of the common transmission path through orientation mode i, locating mode 5, and reconfiguration mode. The above is a case where a break point occurs in the common transmission line, but if there is no abnormality such as a break anywhere on the transmission line, such as when starting up the system,
There is a possibility that the above-described reconfiguration operation will be repeated infinitely.

Countermeasures against this problem 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 connecting the terminal 7b and the terminating resistor 5a
This is the case when 4d is changed.

The switches 4c and 7d 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 manner in a ring as shown in Figure 5, the common transmission path can be started by manually turning switch 4c or 4d at any one station to start the system. is easier to understand than the above explanation. After the system starts up, return switch 4c or 4d that was previously set to manual to automatic.
Even if an abnormality such as a disconnection occurs in the transmission line after that, there will be no problem in reconfiguring the common transmission line. In addition, this invention
In addition to the common transmission path of the data highway explained so far,
It is also applicable when the common transmission path is configured with a plurality of cables, when the common transmission path is multiplexed, and even when the common transmission path is short (for example, a common transmission path between devices).

Further, it is needless to explain that if the transmission line connecting each station does not go around, two sets of common transmission lines with both ends will be reconfigured. BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1, 2, and 3 are diagrams showing configuration examples of conventional common transmission lines.

Figure 4 is a circuit diagram of an example of a station configuration according to the present invention, Figures 5 and 6 are circuit diagrams showing switching states before and after an abnormality occurs in a plurality of stations, and Figure 7 is a diagram from Figure 4. FIG. 8 is a detailed circuit diagram of a modification of the circuit of FIG. 7, and FIGS. 9 and 10 are circuit diagrams for explaining a mode in which an abnormality has occurred. SI~Si-
1, Si, Si11~Sn...Station,
1, li-1, li, li-1...transmission line, 4
a, 4b, 4c, 4d....Switch switch, 5a, 6
b...Terminal resistor, 6...Receiver/dry/ゞ. O diagram 2 diagrams 3 diagrams 4 diagrams

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 stations is performed between any two stations via this common transmission path, a termination is established for each station. A unit and a switching means are provided, and when an abnormality occurs in the transmission line, the stations on both sides of the part where the abnormality has occurred disconnect the transmission line in which the abnormality has occurred from the station, and connect the terminating unit instead. A configuration method of a common transmission line characterized in that the terminals are terminated at stations on both sides of the part where the abnormality occurs.