JPH02161848A - Station connecting order confirming system for loop communication system - Google Patents

Abstract

PURPOSE:To permit a control station to confirm the station connecting order by securing such a constitution where the control station has an answer frame transmitted to a certain station and changes successively the station to confirm the connecting order of the specific stations in accordance with the presence or absence of the answer frame. CONSTITUTION:The transmission lines 11 and 13 are cut at a cutting point 15, and both stations 5 and 7 are kept in a loop-back state respectively. Under such conditions, the direction where a specific station is positioned is detected and a control station 1 gives a loop-back instruction to the specific station. Then the station 1 transmits a frame to a certain station and waits for an answer frame to be returned from the station to change successively this station and to confirm the connection order of specific stations in accordance with the presence or absence of the answer frame. As a result, the station 1 can confirm the station connecting order even in a loop-back state with use of a basic transmission/reception function.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Applications!l!f) The present invention relates to a method for checking the connection order of stations in a loop communication system, and the present invention relates to a method for confirming the connection order of stations in a loop type communication system. This invention relates to a method for determining the connection position and order of stations at any time.

(Prior Art) In a loop communication system consisting of multiple stations connected to a double-loop transmission path and a control station that controls and monitors them, conventionally the control station recognizes the connection order of each station. For this purpose, the following method was adopted.

When the control station issues a loopback instruction to a specific station, and the control station also sends a frame to a certain station, if the certain station is on the upstream side of the main transmission path than the specific station, the response frame sent by that station will be sent to the control station. can be received. If a certain station continues to be sequentially moved downstream on the main transmission path and the certain station comes to be located downstream of the specific station, the response frame will no longer reach the control station.

In this way, the control station confirms the location of the specific station by checking the presence or absence of a response frame. In this case, the specific station refers to, for example, a newly joined station, and the certain station refers to one of the other stations. Furthermore, in the state before the specific station loops back, the station through which information passes first along the main transmission path is defined as the upstream side, and the station through which information passes later is defined as the downstream side.

However, in this method, if a new station joins while in a loopback state due to a failure in the transmission path, the newly joined station is designated as a specific station, a loopback instruction is issued, and the control station The control station sends frames sequentially along the main transmission path and waits for a response frame, but when a frame sent from the control station to a certain station is looped back from the main transmission path to the sub-transmission path and reaches the station, a specific station When downstream from a certain station, the specific station is looped back, so the response frame from the certain station does not reach the control station.

In this way, even if a certain station is located upstream of the specific station, the response frame does not reach the control station and the control station misidentifies the location of the specific station.

(Problems to be Solved by the Invention) The present invention eliminates the above-mentioned drawbacks and provides a loop communication system that enables a control station to reliably confirm the connection order of stations when the loop communication system is in a loopback state. The purpose is to provide a method for confirming the order of station connections.

[Structure of the Invention] (Means for Solving the Problem) In order to achieve the above object, the present invention connects a control station and a plurality of stations in a loop through a main transmission path and a sub-transmission path,
In a loop communication system that circulates frames on these transmission paths to communicate between each station, when a loopback state occurs due to a failure in the transmission path, the direction in which a specific station is located is detected, and then the control station The control station issues a loopback instruction to a specific station, then sends a frame to a certain station, waits for a response frame returned from a certain station, changes the station sequentially, and depending on the presence or absence of a response frame returned from a certain station, It is characterized by checking the connection order of specific stations.

(Operation) First, the control station transmits a frame to a specific station, and the control station determines the location of the specific station from the control station through the main transmission path and back to the sub-transmission path based on the direction of the response frame returned from the specific station. It is detected whether it is located on a loop (hereinafter abbreviated as system 1) or on a loop (hereinafter abbreviated as system 2) extending from the control station through a sub-transmission path and back to the main transmission path.

When a specific station is located in system 1, first a loopback instruction is given to the specific station, and then the control station sends a frame to a certain station from the main transmission path. After the station receives the frame, the control station can receive the response frame to be transmitted from the sub-transmission path. If a certain station continues to be moved downstream sequentially in this way, the certain station will be located downstream of the specific station, and in this case, the response frame will not reach the control station. Therefore, it can be seen that the specific station is located immediately before the station on the upstream side from which no response frame is returned.

In addition, when a specific station is located in system 2, first a loopback instruction is given to the specific station, and then the control station transmits a frame to a certain station from the sub-transmission path. In some cases, after a certain station receives a frame, the control station cannot receive the response frame to be transmitted from the main transmission path. If a certain station continues to be moved downstream sequentially in this way, the certain station will be located downstream of the specific station, and in this case, the response frame will reach the control station via the main transmission path. Therefore, it can be seen that the specific station is located immediately before the station on the upstream side from which the response frame is returned.

In this manner, the control station can confirm the location of the specific station by checking the presence or absence of a response frame.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a block diagram of a loop communication system, and as shown in the figure, control station 1 and stations 3.5.7.9 are connected by a main transmission path 11 and a sub-transmission path 13. 1
1.13 is cut off by cutoff point 15, and stations 5 and 7 are in a loopback state.

FIG. 2 is a diagram showing the loop connection state of the control station. have Figure 2 (A) shows the two-way transmission/reception mode (hereinafter abbreviated as 5VS7), and Figure 2 (B) shows the loopback mode from the main transmission line to the sub-transmission line (hereinafter referred to as 5VS7).
It is abbreviated as S3. ), FIG. 2(C) is a loopback mode from the sub-transmission line to the main transmission line (hereinafter abbreviated as 5VS4).

).

Figure 3 shows the format of a frame used in a loop communication system, and the flenome is the frame header (
FH) 17, destination address (DA) 19, source address (SA) 21, information field (DATA) 23,
It consists of a frame check sequence (Fe2) 25. Frame header (FH) 1.7 indicates the beginning of the frame. The destination address (DA) 19 contains the station address of the station or control station that should receive this frame. The source address (SA) 2 contains the station address of the control station or station that sent this frame.The information field (DATA) 23 contains control information exchanged between the control station and the station. , response information and other information is entered. Frame check sequence (FCS) 25 includes a value for checking errors during frame reception. Figure 4 shows a station connection configuration table (hereinafter abbreviated as configuration table) constructed and stored in the control station.
Here is an example.

The table contains the station address 27 and detailed information 2 of that station.
Consists of one. Each element shown in a horizontal line in the configuration table corresponds to a control station or one station. The elements are arranged along the direction in which the frame flows through the main transmission path. 7 Therefore, in a loop communication system like the one shown in Figure 1, the fourth
A configuration table as shown in the figure is created in the control station]. Note that the station addresses of control station 1- and station 3.5.7.9 are #11, #12, #13, #14, and #15, respectively.

Next, the operation of this embodiment will be explained. For example, as shown in FIGS. 5 and 6, the control station] and station 3.5.7.9
A case will be described in which a new station 27 with a station address #16 joins the loop communication system consisting of the following. The control station 1 had a configuration table 17 as shown in FIG. 4 before the station 27 joined. FIG. 9 is a flowchart showing the operation of this embodiment.

First, control station 1 sets station 27, which has newly joined, as a loopback station (step 901).Next, the control station checks its current mode and if it is 5VS4, station 27 is in system 1. It is found (step 903), and the process proceeds to step 917.If it is 5VS3, it is found that the station 27 is in system 2 (step 903), and the process proceeds to step 905.If it is in any other mode, the control station is 5VS7, as shown in FIG. The address of station 27 is included in one destination address of the form 1 norm shown in
The station address of the control station is entered in [source address 2], and the control information instructing loopback operation is entered in the information field 23, and sent to both the main transmission path 11 and the sub-transmission path 13, and the response frame is sent to both systems. The direction in which the station 27 is located can be determined by whether the station 27 can be received. In other words, when the response frame is received from the sub-transmission path 13, the station 27
When the response frame is received from the main transmission path 11, it is found that the station 27 is in the system 2, and the process proceeds to step 905. Next, a loopback instruction is given to the station 27 (steps 905 and 917).

The station 27 specified by the destination address 19 receives the frame, analyzes the loopback control information in the information field 23, and performs a loopback operation. Next, control station 1 communicates with station 3, which is the first element of the configuration table as shown in FIG. That is, the frame shown in FIG. 3 is transmitted with the station address of station 3 in the destination address j9, the station address of the control station 1 in the source address 21, and the control information that requires a response in the information field 23 (step 909.921). The station 3 specified by the destination address]9 receives the frame, analyzes the control information in the information field 23, and transmits a response frame. The response frame is still in the same format as the frame shown in Figure 3, and this time the destination address 1.9 contains the station address of control station 1,
The source address 21 contains the station address of the station 3, and the information field 21 contains response information.

As shown in FIG. 5, when the new participating station 27 is in system 1, the response frame sent from station 3 to the main transmission path 11 is looped back from the main transmission path 11 to the sub-transmission path 13 at the new participating station 27. The signal is then looped back and further transmitted to the control station 1 via the station 3 on the sub-transmission line 13. Control station 1 sends the response frame to sub-transmission path 1.
3, and the response frame is sent to the sub-transmission path 13.
(step 923), it learns that the new participating station 27 is downstream from the station 3 with respect to the main transmission path 11,
The next station to communicate with is searched again from the configuration table (step 925). In other words, in the configuration table, main transmission path 11
Since there is station 5 downstream of station 3 (step 9
27), communicate with this station (step 921)
.

Since station 5 is looping back to the new participating station 27 upstream of the main transmission path, control station 1 cannot receive the response frame from station 5 (step 92B), so new participating station 2
7 is between stations 3 and 5, and modifies the configuration table as shown in FIG. 7 (step 929).

Also, when station 27 is added between cutoff point 15 and station 5, station 27 is similarly set as a loopback station and step 901
), control station 1 communicates with station 3 and station 5 in order from the configuration table (step 921), but this time both can receive response frames and communicates with station 7 again (steps 923, 925, 927). . However, since station 7 is in system 2 and control station 1 cannot receive the response frame from sub-transmission line 13, it learns that station 27 is between stations 5 and 7 and changes the configuration table (step 929).

As shown in FIG. 6, when the new participating station 27 is in system 2, control station 1 monitors the response frame on main transmission line
The response frame sent from station 3 to main transmission line 1 is looped back from main transmission line 11 to sub-transmission line 13 at station 5, and reaches control station 1 from sub-transmission line 13, but the main transmission Since there is no path 11, it is not considered a response frame. Since no response frame is received, the next station to communicate with is searched again from the configuration table (step 913). Based on the configuration table, it then communicates with station 5, but does not receive a response frame for the same reason as station 3. Furthermore, whether to communicate with station 7 from the configuration table (step 909), this time control station 1
The station 7 transmits a response frame to the main transmission line 11 in response to the frame transmitted from the sub-transmission line 13. However, since the new participating station 27 is looping back, the response frame does not reach the control station 1.

Next, communicate with station 9 from the configuration table (Step 909)
, the response frame is looped back from the sub-transmission path 13 to the main transmission path 11 by the new participating station 27 and transmitted from the main transmission path 11 to the control station 1, and the control station 1 recognizes that the new participating station 27 is between stations 7 and 9. , and corrects the configuration table as shown in FIG. 8 (step 929).

Also, if station 27 is added between cutoff point 15 and station 7, station 27 is similarly set as a loopback station and step 901
), control station 1 communicates with station 3 and station 5 in order from the configuration table (step 909), and is able to receive response frames from both of them and communicates with station 7 again (step 911).
913.915). This time, control station 1 can receive the response frame returned from station 7 from main transmission path 11, so station 2
7 is between stations 5 and 7, and changes the configuration table (step 929).

In this way, in this embodiment, the control station can recognize the connection order of stations even during loopback using only the basic transmission and reception functions.

[Effects of the Invention] As explained above, according to the present invention, the control station can check the connection order of stations even during loopback using only basic transmitting and receiving functions.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of a loop communication system, Fig. 2 is a loop connection state diagram of a control station, Fig. 3 is a frame format diagram, and Fig. 4 is a diagram showing a configuration table possessed by a control station.
Figures 5 and 6 are configuration diagrams of the loop communication system when a new participating station appears, Figures 7 and 8 are diagrams showing revised configuration tables, and Figure 9 is the operation of this embodiment. It is a flowchart which shows. 1......Control station 3.5.7.9.27...Station 11...Main transmission line 13...Sub transmission line 15...... Cutoff point

Claims (1)

[Claims] In a loop communication system, a control station and multiple stations are connected in a loop through a main transmission path and a sub-transmission path, and frames are circulated around these transmission paths to communicate between each station.
After the control station detects the direction in which the specific station is located while the loop is looped back, the control station issues a loopback instruction to the specific station, and then the control station sends a frame to a certain station, which returns the frame. A station connection order confirmation method for a loop communication system characterized by waiting for a response frame, sequentially changing certain stations, and checking the connection order of specific stations based on the presence or absence of a response frame returned from a certain station.