JPH01143539A - Station connection sequence confirming system for looped communication system - Google Patents

Abstract

PURPOSE:To confirm the connection sequence of all slave stations by means of a basic transmission reception function only by sending a station address request frame after the transmission of a loopback request frame from a master station to all the slave stations. CONSTITUTION:The master station 1 having a control function and slave stations 2, 3, 4 having a basic transmission reception function are connected in a loop by inner and outer double transmission lines 5, 6. Moreover, a frame is circulated cyclicly to the transmission lines 5, 6. After sending a loopback request frame to the slave stations 2, 3, 4, the master station 1 sends a station address request frame to all the slave stations till the slave stations in the loopback state do not exist. Then station address information is extracted and stored from a station address acknowledge frame sent from any slave station and a loopback release request frame is sent to the slave station and the operation is repeated. Thus, the connection sequence of all slave stations is confirmed by means of a basic transmission reception function only is a short time.

Description

[Detailed description of the invention] :Object of the invention] An industrial field of application
In particular, the present invention relates to a method that does not require a special transmitting/receiving function to check the connection order, and can grasp the connection positions and order of all slave stations at once using only basic transmitting/receiving functions.

(Prior art) Loop communication has conventionally connected multiple slave stations and a master station that controls and monitors them in a loop through dual internal and external transmission lines, and communicates by circulating frame-format signals on the transmission lines. There is a system.

Figure 6 shows such a loop communication system, in which the master station 1 and slave stations 2, 3, 4 are connected to an internal and external duplex transmission line 5.
．． 6 are connected in a loop.

In transmission #t6, a frame is periodically circulated, and each station detects this frame and adds data to this frame, thereby performing communication between each station.

By the way, in such a loop communication system, it is necessary to know the relative connection position of a specific slave station, for example, when starting up the system.

For this reason, it is conceivable to provide each station with a special transmitting and receiving function for checking the connection order, for example.

However, in this case, the hardware configuration of each station becomes complicated and there is a cost problem.

Therefore, a method can be considered in which the connection order is confirmed using only basic transmission and reception functions.

In other words, this method recognizes that a specific slave station placed in a loopback state stops communicating with other slave stations and the master station, and learns the relative connection position of the specific slave station. An example of this will be explained in more detail below.

First, the master station issues a loopback instruction to a specific slave station whose relative connection position is unknown.

Next, the master station transmits a frame with a command to send a response frame back to the master station when the frame is received to any slave station other than a specific slave station, and waits for a response frame from the slave station. .

Then, when the main station is able to obtain a response frame,
The specific slave station knows that it is downstream from the slave station that transmitted and received the frame. On the other hand, when a response frame cannot be received, it is known that a specific slave station is located upstream of the slave station that transmitted and received the frame.

By sequentially changing the partner slave station for frame transmission and reception, the connection position of the specific slave station can be known.

However, in this method, in order to know the connection position of a specific slave station, it is necessary to perform the above-mentioned frame transmission and reception communication between other slave stations and the master station. It is only possible to recognize the connection position.

For this reason, when it becomes necessary to know the connection order of all slave stations, such as when starting up the entire system of a loop communication system, the processing efficiency is poor and the process takes a long time. There is a problem that it is necessary.

(Problems to be Solved by the Invention) As described above, methods for confirming the order of station connections in conventional loop communication systems include methods in which each station is provided with a special transmitting and receiving function for confirming the order of connections, and methods such as the above-mentioned method. It is possible to consider a method of checking the connection order using only basic sending and receiving functions, as in There is a problem in that it requires

The present invention has been made based on the above circumstances, and provides a station connection order confirmation method for a loop communication system that can confirm the connection order of all slave stations at dead time using only basic transmitting and receiving functions. The purpose is to

[Structure of the Invention] (Means for Solving the Problems) The present invention connects a master station having a control 0!1 function and a plurality of slave stations having basic transmitting and receiving functions in a loop through a double transmission path. In the loop communication system that performs communication by circulating frames on the transmission path, the main station transmits a loopback request frame to all the slave stations, and then transmits the loopback request frame to all the slave stations until there are no slave stations in the loopback state. A station address request frame is transmitted to all the slave stations, and then a station address response frame transmitted by one of the slave stations in the loopback state is received, and the station address information is extracted from this station address response frame and sent to this station. It stores address information and repeatedly transmits a loopback release request frame to the slave station having the station address.

(Function) In the present invention, first, the master station sends a loopback request frame specifying a broadcast destination address to put all slave stations into a loopback state, and then sends a station address request specifying a -broadcast destination address. Send a frame.

On the other hand, when the slave station receives the station address request frame, if the slave station is in a loopback state, it transmits a station address response frame containing the station address information of the slave station to the master station.

By the way, in a slave station that is in a loopback state, for example, when looping back from an outer transmission line to an inner transmission line, the normal inner transmission line is disconnected, it is connected to the outer transmission line, and the outer transmission line is connected to the outer transmission line. Frames that have entered the transmission path are output from the inner transmission path, and frames that have been input from the inner transmission path are discarded.4Here, the flow of frames is blocked on the transmission path that includes the slave station in the loopback state, and all slave stations Even if station address response frames are transmitted, not all station address response frames reach the master station, and only station address response frames transmitted by slave stations adjacent to and downstream of the master station are received by the master station.

Then, the main station extracts the station address information from this station address response frame and stores it. As a result, the master station learns of the first slave station in the downstream direction of the transmission path.

Thereafter, the master station transmits a loopback release request frame to the first slave station, and then again transmits a station address request frame specifying the broadcast destination address.

When the slave station receives the station address request frame, it transmits the station address response frame in the same manner as described above.

Here, since the first slave station located downstream adjacent to the master station is not in a loopback state, it does not transmit the station address response frame, and the station address response frame received by the master station is transmitted to the second slave station in the downstream direction of the transmission path. This is the frame transmitted by the slave station.

Then, the master station extracts and stores the station address information from this station address response frame, and transmits a loopback release request frame to the second slave station. Thereafter, the master station similarly stores the station address information of the slave stations in the downstream direction by repeating the transmission of the station address request frame and the reception of the station address response frame until there are no slave stations in the loopback state. However, the master station can finally recognize the connection order of all slave stations on the transmission path.

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

FIG. 1 is a diagram showing the configuration of a loop communication system according to an embodiment of the present invention.

In the system shown in the figure, a master station 1 having a control function and a slave station 2.3.4 having a basic transmitting/receiving function are connected in a loop by a dual-internal/internal transmission line 5.6. In addition,
Here, the outer transmission line 5 is assumed to be the main transmission line, and the inner transmission line 6 is assumed to be the sub-transmission line.

In addition, in transmission #15.6, a frame is circulated periodically, and each station detects this frame and adds data to this frame, thereby communicating between each station6.
Here, it is assumed that the frames circulating around the outer transmission path 5 rotate clockwise in FIG. 1, and the frames circulating around the inner transmission line 5 rotate counterclockwise in FIG. 1.

FIG. 2 is a format diagram of a frame circulating around the transmission line 5.6.

The frame shown in the figure is frame header (FH) 7.
, destination address (DA) 8, source address (SA) 9
, an information field (INFO) 10 and a frame check sequence (Fe2) 11.

A frame header (FH) 7 indicates the beginning of the frame.

Destination address (DA) 8 is the source address (including the station address of the slave station or master station that should receive this frame).
SA)9 includes the station address of the master station or slave station that transmitted this frame.

The information field (INFO) 10 contains control information, response information, and other information data exchanged between the master station and the slave station. Frame check sequence (Fcs)li
contains a value that checks for errors when receiving the frame.

Next, the operation when it becomes necessary to know the connection order of slave stations in this loop communication system is explained in Figures 3 to 5.
This will be explained with reference to the figures. Note that FIG. 4 shows the flow of processing in the master station, and FIG. 5 shows the flow of processing in the slave station.

First, the master station 1 inputs a broadcast address that instructs all slave stations in the destination address 8 of the frame, the station address of the master station 1 in the source address 9, and control information that instructs loopback operation in the information field 10. A simultaneous loop pack request frame including the loop pack request frame is transmitted (step 401).

The slave station 2 that received this simultaneous loop pack request frame.
3.4 (steps 501 and 502) information field 1
It interprets the loopback instruction control information of 0 and enters the loopback state (see FIG. 3 <a), step 503).

After transmitting the simultaneous loopback request frame as described above, the master station 1 transmits the loopback request frame to all slave stations 2.3 as described above.
．． 4 is in the loopback state, the destination address 8 of the frame is the broadcast address, the source address 9 is the station address of the main station 1, and the information field 10 is the control information that instructs to request a station address. A broadcast address request frame containing the information is transmitted (step 402).

Each slave station 2 that received this simultaneous station address request frame.
3.4 interprets the station address request control information in the information field 10 (step 504) and transmits a station address response frame to the main station 1 when the own station is in the loopback state (step 505). For example, the slave station 2 that received the simultaneous station address request frame in the loopback state enters the station address of the master station 1 in the destination address 8 of the frame, the station address of the slave station 2 in the source address 9, and the station address in the information field 10. Station address response frames each containing response information instructing a response are transmitted. Similarly, the slave stations 3 and 4 also transmit station address response frames in which the respective station addresses of their own stations are entered in the source address 9.

Here, each slave station 2.3.4 currently in loopback state
As shown in FIG. 3(a), the sub-transmission line 6 is cut in each slave station 2.3.4. Therefore, the station address response frames transmitted by slave stations 3.4 other than slave station 2 are blocked by slave stations 2.3, and only the station address response frames transmitted by slave station 2 are received by master station 1.

Note that the main station 1 ignores the station address response frame that arrives via the main transmission path 5.

The main station 1 which thus received the station address response frame from the sub-transmission path 6 (step 403) interprets the source address 9 and the station address response information in the information field 10,
It is learned that the slave station 2 is located closest to the downstream direction of the main transmission path 5, and the station address of this slave station 2 is stored (step 404).

After this, the master station 1 sends the slave station 2 the station address of the slave station 2 in the destination address 8 of the frame, the station address of the master station 1 in the source address 9, and sends a control request to cancel the loopback state in the information field 10. A loopback release request frame each containing information is transmitted (step 405).

The slave station 2 that received this loopback release request frame (step 507) interprets the loopback release request control information in the information field 10 and releases the loopback state (
See FIG. 3(b), step 508).

Thereafter, such operations are performed until there are no slave stations in the loopback state.

That is, the main station 1 transmits a simultaneous station address request frame.

Here, since slave station 2 is not in the loopback state, slave station 2
Since the station address response frame from the slave station 4 is not sent to the master station 1, and since the slave station 3 is currently in a loopback state, the station address response frame transmitted by the slave station 4 is blocked by the slave station 3. Only the station address response frame sent by the main station 1 is received by the main station 1. Note that, similarly to the above, the main station 1 transmits the main transmission P! Station address response frames arriving via 5 are ignored.

In this way, the main station 1 which received the station address response frame from the sub-transmission path 6 sends the source address 9 and the information field 1.
It interprets the station address response information of 0, learns that there is a slave station 3 at the second downstream position of the main transmission line 5, and stores the station address of this slave station 3.

Thereafter, the master station 1 transmits a loopback release request frame to the slave station 3.

The slave station 3 that receives this loopback release request frame interprets the loopback release request control information in the information field 1o and releases the loopback state (see Figure 3(c)).
.

Thereafter, the main station 1 transmits a simultaneous station address request frame.

Here, since slave station 2.3 is not in the loopback state, the station address response frame from slave station 2.3 is not sent to master station 1. Therefore, only the station address response frame transmitted by slave station 4 is sent to master station 1. received at Note that, similarly to the above, the main station 1 ignores the station address response frame that arrives via the main transmission path 5.

In this way, the main station 1 which received the station address response frame from the sub-transmission path 6 sends the source address 9 and the information field 1.
It interprets the station address response information of 0, learns that there is a slave station 4 at the third downstream position of the main transmission line 5, and stores the station address of this slave station 4.

Thereafter, the master station 1 transmits a loopback release request frame to the slave station 4.

The slave station 4 that received this loopback release request frame interprets the loopback release request control information in the information field 10 and releases the loopback state (see FIG. 3(d)).
.

Thereafter, the main station 1 transmits a simultaneous station address request frame.

Here, since the slave station 2.3.4 is not in the loopback state, the station address response frame from the slave station 2.3.4 is not sent to the master station 1. In other words, the master station 1 has no station address response frame. The master station 1 sends a simultaneous station address request frame and then waits to receive a station address response frame from the slave station, but if the station address response frame is not received within a certain period of time, the slave station is in a loopback state. The process ends as if it does not exist.

In this way, in this embodiment, the main station 1 and the slave stations 2.3.4
Even if there are no special functions, the master station can know the connection order of the slave stations just by using basic transmitting and receiving functions. Therefore, the hardware configuration of each station can be simplified and costs can be reduced.

In addition, after issuing a loopback instruction once, the connection positions of all slave stations can be recognized by simply repeating the transmission/reception of station addresses and cancellation of loopback, so this is useful, for example, when starting up the entire system of a loop communication system. - Especially when it becomes necessary to know the connection order of all slave stations, the processing efficiency is particularly high and the processing can be carried out in a short time.

[Effects of the Invention] As described above in detail, according to the present invention, the connection order of all slave stations can be confirmed in a short time using only basic transmitting and receiving functions.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a loop communication system according to an embodiment of the present invention, FIG. 2 is a frame format diagram applied to the system of this embodiment, and FIGS. 3(a) to (d)
) is a diagram showing the state transition of each slave station due to the processing of this embodiment, FIG. 4 is a flowchart showing the processing of the master station in this embodiment, and FIG. 5 is a flowchart showing the processing of the slave station in this embodiment. , FIG. 6 is a diagram showing the configuration of a loop type communication system. 1...Main station, 2.3.4...Slave station, 5...Main transmission line 6...Sub transmission line. Applicant Toshiba Corporation Patent Attorney Sasa Suyama - Figure 1 Figure 2 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] (1) In a loop communication system in which a master station with a control function and a plurality of slave stations with basic transmitting and receiving functions are connected in a loop through a double transmission path, and communication is performed by circulating frames on the transmission path. , after transmitting a loopback request frame to all the slave stations, the master station transmits station address request frames to all the slave stations until there are no slave stations in the loopback state, and then the master station returns to the loopback state. receives the station address response frame transmitted by one of the slave stations in the station address response frame, extracts station address information from this station address response frame, stores this station address information, and cancels loopback for the slave station having the station address. A station connection order confirmation method for a loop communication system characterized by repeatedly transmitting request frames.