JPH0265548A - Group name access method - Google Patents

Abstract

PURPOSE:To connect both terminal equipments simply through one frame transmission and reception by transmitting connection request frame including a destination group name representing a group name of a terminal equipment group and a flag representing the presence of a receptible terminal equipment as a multiple address frame or group multiple address. CONSTITUTION:A terminal equipment a 11 sends a connection request frame as a multiple address frame. When a printer A 21 receives the said connection frame, since the printer A 21 is busy and disabled of connection, a flag A representing the coincidence of the address of the bits 0 and 4 in the FS section of the connection request frame is set. Then when a printer B 22 receives the connection request frame, since the group name is 'printer', the printer B 22 is able to be connected and no flag R is set to bits 2, 6 in the FS section, the printer B 22 starts the connection reply to the terminal equipment a 11.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is applicable to a terminal in a network system accommodating a plurality of terminals in a loop-shaped signal transmission path, to a terminal group consisting of one or more terminals. The present invention relates to a group name access method for accessing an arbitrary terminal in a group using a predetermined group name.

<Prior Art> Conventionally, as a group name access method in a network system accommodating a plurality of terminals on a loop-shaped signal transmission path, there is a method using the following procedure.

■ The calling terminal transmits a connection request frame containing the destination group name as a simultaneous broadcast frame to all terminals.

(2) The terminal that receives the connection request frame sent from the calling terminal checks the destination group name in the received connection request frame. Then, if the destination group name is not decoyed by the own terminal, the connection request frame is relayed as is. - On the other hand, if this is the destination group name to which the own terminal belongs, and the own terminal is in a state where it can be connected to the calling terminal, it transmits a connection response frame to the calling terminal.

(2) When the calling terminal receives the connection response frame, it confirms the connection with the destination terminal by replying an acknowledgment frame to the destination terminal that sent the connection response frame.

<Problem to be Solved by the Invention> However, in the above conventional group name access method, the received connection request frame is the destination group name to which the own terminal belongs, and the own terminal is connectable to the above calling terminal. If the terminal is in the state, a connection response frame is sent to the calling terminal, so if the destination group name is the group name to which the terminal belongs, and the terminal is in a state where it can connect to the calling terminal, If the number is large, a connection response frame is transmitted from all of these terminals to the calling terminal. Therefore, a calling terminal that has received a plurality of connection response frames can transmit the above-mentioned acknowledgment frame in response to one connection response frame. However, there is a problem in that a negative response frame must be transmitted for all other connection response frames, which requires extra processing.

Additionally, if multiple different calling terminals successively send connection request frames to a terminal group with the same group name, the terminals in the called terminal group will first transmit the connection request frame. Since the connection response frame is sent only to the calling terminal, there is also a problem in that the transmission of the connection response frame to the calling terminal that subsequently sent the connection request frame is delayed.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to enable a calling terminal and any terminal in a terminal group to easily connect the two terminals by just sending and receiving a single frame, and to To provide a group name access method that does not delay a response to a calling terminal that transmits a connection request frame later when connection request frames are successively transmitted from a terminal to the same terminal group.

<Means for Solving the Problems> In order to achieve the above object, the first invention accommodates a plurality of terminals in a loop-shaped signal transmission path, and uses one or more terminals among the plurality of terminals as a component. In a network system configured with a terminal group, from a terminal that does not belong to the above terminal group to any one terminal within the above terminal group,
In the group name access method of accessing the terminal group using a group name given in advance to the terminal group, the calling terminal connects a destination group name representing the group name of the terminal group and a flag indicating that there is a terminal capable of receiving the terminal. When a request frame is transmitted as an imperial broadcast frame or a group broadcast, and a terminal other than the calling terminal receives the connection request frame,
Determine whether or not the destination group name included in the connection request frame is the group name of the terminal group in which the terminal exists, and if the destination group name is the group name in which the terminal exists, and the terminal is in a state where it can be connected to the calling terminal and the flag included in the connection request frame is not set, the terminal sets the flag in the connection request frame and relays it, and then A connection response frame containing information representing connectable terminals is transmitted to the calling terminal, while the destination group name is a group name in which the terminal exists, and the terminal is connected to the calling terminal. Even if there is a possible error, if the flag included in the connection request frame is already set, the connection request frame is relayed as is, and the calling terminal transmits the loop signal transmission path. Based on the flag in the connection request frame that has returned after one cycle, it is determined whether a terminal that can connect to the terminal group grows or not. The device is characterized in that the connection partner terminal is recognized based on the connection response frame that is received.

Further, a second invention is a network system in which a plurality of terminals are accommodated in a loop-shaped signal transmission path, and a terminal group is configured with one or more terminals among the plurality of terminals as a constituent element, wherein the network system includes a plurality of terminals that belong to the terminal group. In a group name access method in which an arbitrary terminal in the terminal group is accessed from a terminal that does not access the terminal group using a group name given in advance to the terminal group, the calling terminal accesses a destination group representing the group name of the terminal group. A connection request frame containing the name is sent as an Imperial Palace circular frame or a group circular, and terminals other than the above-mentioned calling terminal,
When the connection request frame is received, it is determined whether the destination group name included in the connection request frame is the group name of the terminal group in which the terminal exists, and if the destination group name is If the group name exists, and the terminal is in a state where it can connect to the calling terminal, and the address of another terminal is not added to the connection request frame, the terminal will issue the connection request. While adding the address of the above terminal to the frame and relaying it, even if the above destination group name is the group name in which the above terminal exists and the above terminal is in a state where it is possible to connect to the above calling terminal, If the address of another terminal is added to the connection request frame, the connection request frame is relayed as is, and the calling terminal receives the connection that has returned after going around the loop-shaped signal transmission path. While determining whether there is a connectable terminal in the terminal group based on whether the address of another terminal is added to the request frame,
It is characterized in that the connection partner terminal is recognized by the address of the other terminal added to the connection request frame.

<Example> Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

FIG. 1 shows a network system according to the present invention.

In this network system, a plurality of terminals are accommodated in a network formed in a loop, and frame transmission rights of each terminal are sequentially transferred to each terminal.

In FIG. 1, l is a signal transmission path, 11 is a terminal such as a computer (a), 12 is a terminal such as a computer (b), 2
1 is a printer (A) which is a terminal, 22 is a printer (B) which is a terminal, and 23 is a printer (C) which is a terminal.

Here, upper P! , three printers (A) 21, printer (B) 22, and printer (C) 23 form one terminal group, which can be accessed using the group name "Printer." Assume that the printer (A) 21 is currently in operation and cannot be connected to other terminals.

FIG. 2 (s”) shows that the calling terminal (a) 11 or terminal (b) +2 is connected to the printer (A) 21.
An example of the structure of a frame transmitted to a called terminal group consisting of B) 22 and printer (C) 23 is shown. This frame includes a delimiter indicating the start/end of the frame, a control section, a destination address, a source address, a data section, a frame check sequence section (hereinafter referred to as Fe2), and a frame status section (hereinafter referred to as FS section). ).

As shown in FIG. 2(b), the FS section contains a flag (A) that notifies the address match of the terminal that received this frame, and a flag (R) that indicates the existence of a connectable terminal.
)It is included.

Hereinafter, in the network system having the above configuration, the procedure of the access method when the terminal (a)ll connects to any one printer in the called terminal group with the group name "printer" will be explained.

(1) Terminal (a) 11 transmits a connection request frame with the contents of the frame configured as shown in FIG. 2(a) set as shown in FIG. 2(C) as a -broadcast frame. . This connection request frame sets the group name "Printer" in the data section, sets "Group Name Connection Request" in the control section, sets "-broadcast" in the destination address, and sets the source address as "-Broadcast". “Setting up terminal a.

(2) The connection request frame is transmitted in the direction shown by the arrow in FIG. 1, and is first received by the terminal (b) 12. The terminal (b) 12 then checks the group name set in the data portion of the received connection request frame. Then, the group name set is terminal (b)
Since this is not the group name of the terminal group to which 12 belongs, terminal (b) + 2 relays this connection request frame as is. Here, this connection request frame is similarly relayed as is to all other terminals that do not belong to the terminal group whose group name is "Printer J."

(3) Next, the printer (A) 21 receives the connection request frame. Then, the printer (A) 21 checks the group name set in the data portion of the received connection request frame. Then, the set group name is the group name "Printer" of the terminal group to which the printer (A) 21 belongs, but since the printer (A) 21 is in operation and cannot be connected, the printer (A) 21 is in operation and cannot be connected. ) 21 is a flag (
Set A). Then, after setting the flag (A), relay transmission is further carried out in the direction of the arrow.

(4) Next, the printer (B) 22 receives this connection request frame. Then, the printer (B) 22 checks the group name set in the data section of the received connection request frame. Then, the set group name is "Printer" and the printer (B) 22
The printer (B
) 22 starts a connection response operation for the terminal (aNl).

(Also, at this time, if the flag (A) indicating address match in the connection F'S part is not set, the flag (
Set A). ) That is, the printer (B) 22 sets a flag (R) indicating that there is a connectable terminal in the PS section, and sends a connection response to the terminal (a) 11 as shown in FIG. 2(d). Create a frame and prepare it for transmission. This connection response frame is sent to the control unit as a “group name connection response”.
and enter the group name “Printer” in the data section.
”, the destination address is set to “terminal a”, and the source address is set to “printer B”.

(5) Next, the printer (C) 23 connects the terminal (a) II
Receive a connection request frame sent from.

The group name set in the data section is "Printer", and the printer (C) 23 can be connected. However, since the flag (R) in the FS section has already been set, the printer (C) 23 relays and transmits this connection request frame as is.

(6) The frame transmission right that allows each terminal to transmit a frame moves sequentially from the terminal (a) If to the downstream terminals, and when the printer (B) 22 obtains the frame transmission right, , the printer (B) 22 follows the above procedure (4).
Sends the connection response frame that it was preparing to send.

(7) The calling terminal (a) 11 receives the connection response frame sent from the printer (B) 22, and
B) Confirm that it is connected to 22.

Thereafter, data is transmitted using a data frame as shown in FIG. 2(e). This data frame sets "send data" in the data section, "data send" in the control section, "printer B°" in the destination address, and "terminal a" in the source address. There is.

That is, the calling terminal (in this embodiment, the terminal (ail
) When a connection request frame like the one shown in FIG. 2(c) is transmitted once, while this connection request frame goes around the network system, the terminals that can receive the connection request frame included in the FS part of this connection request frame are A flag (R) indicating that the printer exists is set by a connectable printer (printer (B) 22 in this embodiment), and the printer that has set the flag CR) sends a connection response frame to the calling terminal. is sent. Therefore, by checking the flag (R) of the connection request frame that comes in one cycle, each printer can know whether there is already a printer that can connect to the connection request from the calling terminal. Therefore, if there is already a connectable printer, there is no need to send a connection response frame. In other words, any terminal within the calling terminal and called terminal group can be connected by just one frame transmission/reception.

Next, in FIG. 1, terminal (a) It requests connection to any one printer in the called terminal group "printer j," and then terminal (b) I2 requests connection to the same called terminal. The procedure for accessing an arbitrary printer in the group "printer" when requesting a connection will be described.

(11) When a connection request frame is transmitted from the terminal (a) 11, the printer (B) 22 receives this connection request frame through the same steps as steps (+) to (3) in the above embodiment. do. Then, printer (B) 22
The group name is "Printer", and the printer (B
) 22 can be connected, and the flag (R) indicating that there is a terminal in the Upper FS section that can receive data is not set, so this flag (R) is set and the
) A connection response frame for the terminal (a) 11 is created and prepared for transmission. As a result, the printer (B) 22 is in operation and cannot be connected to other terminals. Further, since the flag (R) is set, the printer (C) 23 relays the connection request frame as it is.

(12) Subsequently, the connection request frame transmitted from the terminal (b) 12 is relayed as is by the operating printer (A) 21, and subsequently received by the printer (B) 22. However, since the printer (B) 22 is already in operation and cannot be connected, the received connection request frame from the terminal (b) 12 is relayed as is. (At this time, if the flag (A) notifying that the addresses in the PS part of the connection request frame match has not been set yet, this flag (A) is set.)
(13) Next, the connection request frame transmitted from the terminal (b) 12 is received by the printer (C) 23.

The printer (C) 23 is connectable, and
FS of the connection request frame from the above terminal (b) l2
Since the above flag (R) within the unit is not set, Blink (C) 23 sets the above flag (rL) and creates a connection response frame as shown in FIG. 2 (r) for terminal (b)+2. and prepare to send. The destination address of this connection response frame is set to "terminal b#," and the source address is set to "printer C."

(I4) Printer (+3) 22 and printer (C)
23, the above (11) and (
13) Send the connection response frame prepared in step 13). Then, the terminal (a) II confirms that it is connected to the printer (13) 22, and the terminal (b) 12 confirms that it is connected to the printer (C
)23.

That is, when each connection request frame is transmitted once from a plurality of calling terminals, the flag (rt) in the FS section of each connection request frame changes while each connection request frame goes around the signal transmission path l. It is set by a connectable printer, and a connection response frame is transmitted from the printer that has set the flag (R) to the calling terminal to be connected. Therefore, by checking the flag (R) of the connection request frame from each calling terminal that comes in a round, each printer can determine whether there is already a printer that can connect to the connection request from each calling terminal. I know that there is. Therefore, in that case, there is no need to transmit a connection response frame. In other words, each calling terminal and any terminal in the called terminal group can establish a connection by just sending and receiving a frame once, and only the calling terminal that first sent the connection request frame can establish a connection between the terminals. Since the connection response frame is not sent first, there is no delay in responding to the calling terminal that subsequently sent the connection request frame.

Next, an example different from the above example will be described.

The network system according to this embodiment is the same as the network system shown in FIG.

FIG. 2(a) shows an example of the structure of a frame transmitted from a calling terminal to a group of called terminals.
As shown in FIG. 3(g), the S section includes a flag (A) that notifies the address match of the terminal that received this frame. Among the terminals that received the connection request frame, the terminals that can be connected are shown in FIG. 3(h).
As shown in , the address of the connectable terminal is added immediately before the FCS section.

Hereinafter, in the network system having the above configuration, the procedure of the access method when the terminal (a) II connects to any one printer in the called terminal group with the group name "printer" will be explained.

(2I) Terminal (a) II transmits a connection request frame as shown in FIG. 3(i) as a simultaneous broadcast frame.

This connection request frame has the group name "" in the data field.
``Printer'' is set, ``Group name connection request'' is set in the control unit, ``-Broadcast'' is set in the destination address, and ``Terminal a'' is set in the source address.

(22) First, the above connection request frame is sent to terminal (b) 12.
received at And terminal (b)'! Step 2 examines the group name set in the data portion of the received connection request frame. Then, since the set group name is not the group name of the terminal group to which terminal (b) 12 belongs, terminal (b)+2 relays and transmits this connection request frame as is. Similarly, this connection request frame is relayed as is to all other terminals that do not belong to the called terminal group whose group name is "printer."

(23) Next, the printer (A) 21 receives the connection request frame. Then, the printer (A) 21 checks the group name set in the data section of the received connection request frame. Then, the set group name is the group name "Printer" to which the printer (A) 21 belongs, but since the printer (A) 21 is in operation and cannot be connected, the printer (A) 21
1 sets the flag (A) in the FS section of the connection request frame. Then, after setting the flag (A), relay transmission is further carried out in the direction of the arrow.

(24) Next, the printer (B) 22 receives this connection request frame. The group name set in the data section of the printer (B) 22 is "Printer".
Since the printer (+3) 22 is connectable and the address of another printer connectable to the terminal (a) If is not added to the connection request frame, the terminal (a)
) Initiate a connection response operation for II. (Also, at this time, a flag (A
) is not set, flag (A) is set. ) That is, the printer (n) 22 adds its own terminal address "Printer B" immediately before the FCS part of the connection request frame, as shown in FIG. 3(D).

(25) Next, the printer (C) 23
1 receives the connection request frame sent from 1.

The group name set in the data field of the received connection request frame is "Printer", and although it is possible to connect to it, the connection request frame already contains information about other printers (B) 22 that can be connected. Since the address has been set, the printer (C) 21 relays and transmits this connection request frame as is.

(26) The calling terminal (a) 11 receives the above connection request frame that has come around and confirms that it has been connected to the printer (B) 22 using the address "Printer B" added to the connection request frame. do. Thereafter, the data is transferred to the printer (
B) Send to 22.

This data frame sets "send data" in the data section, "data transmission" in the control section, "printer B" in the destination address, and "printer B" in the source address.
Terminal a° is set.

That is, when a connection request frame is transmitted once from a calling terminal, one printer (in this embodiment, printer (B) 22) among connectable printers is sent while this connection request frame goes around the network system. ) is added immediately before the FCS part of this connection request frame, and the frame is received again by the calling terminal. therefore,
Each printer can know that a printer that can connect to the calling terminal already exists by checking whether there is another printer's address immediately before the FCS part of the connection request frame that comes in one cycle. can.

Therefore, if there is already a connectable printer, there is no need to respond. In other words, any terminal within the calling terminal and called terminal group can be connected by just one frame transmission.

Next, in FIG. 1, terminal (B) 11 requests connection to any one printer in the called terminal group "printer", and then terminal (b) l 2 requests connection to the same called terminal. The procedure of an access method when a connection is requested to any one printer in the group "printer" will be explained.

(31) When a connection request frame is transmitted from the terminal (a)If, steps (2) to (23) in the above embodiment
), the printer (B) 22 receives this connection request frame. Then, the group name is "Printer", the printer (B) 22 is connectable, and the address of the other connectable printer is not added to the connection request frame.
It adds its own terminal's address "Printer B" and relays it to the next printer. As a result, printer (B) 2
2 is in operation and cannot be connected to other terminals. Furthermore, since the address of the connectable printer (B) 22 is added to the connection request frame, the printer (C) 23 receives the connection request frame as it is from the terminal (a).
) Relay transmission to It.

(32) Subsequently, the connection request frame transmitted from the terminal (b) 12 is received by the printer (B) 22.

However, since the printer (B) 22 is already in operation in step (31) and cannot be connected, the terminal that received the message (
b) Relay and transmit the connection request frame from +2 as is. (At this time, if the flag (A) in the FS part of the connection request frame is not set yet, this flag (A) is set.) (33) Next, the terminal (b)
The connection request frame sent from 12 is the printer (C)
23. And printer (C) 23
is connectable, and since the address of another printer is not added to the direct menu of the FCS part of the connection request frame from the above terminal Cb) 2, the printer (C) 23
adds the own terminal's address "Printer C" to the terminal (a
)If relay transmission.

(34) Terminal (a) 11 and terminal (b) l 2 are
- Receive the connection request frame sent by the visiting terminal and check the address of the attached printer.

Then, the terminal (a) 11 confirms that it is connected to the printer (B) 22, and the terminal (b) 12 confirms that it is connected to the printer (C) 2.
3. Check that it is connected.

That is, when each connection request frame is transmitted once from a plurality of calling terminals, Fe2 of each connection request frame is
Addresses of connectable printers are added to the department's direct library. Therefore, by checking the printer address added to the connection request frame from each calling terminal, each printer can check whether a printer that can connect to the calling terminal already exists. You can know that there is. Therefore, it is best not to respond in such cases. In other words, it is possible to establish a connection between terminals by just sending a single frame from each calling terminal, and only the calling terminal that first sent the connection request frame can establish a connection within the group of called terminals. A capable terminal does not respond, and there is no delay in responding to a calling terminal that subsequently sends a connection request frame.

In each of the embodiments described above, each terminal is accommodated in the loop-shaped signal transmission path 1, but the present invention is not limited thereto. That is, a plurality of stage gins to which a plurality of terminals are connected are connected to the signal transmission path I, the plurality of stage gins are treated as one group, and one stage gin in this group is accessed by group name. Good too.

<Effects of the Invention> As is clear from the above, in the group name access method of the first invention, a calling terminal transmits a connection request frame including a destination group name and a flag as a simultaneous broadcast frame or a group broadcast, A terminal other than the calling terminal that receives the connection request frame determines whether the destination group name is the group name of the terminal group in which the terminal exists, and as a result, it determines whether or not the destination group name is the group name of the terminal group in which the terminal exists. If yes, and the terminal is in a connectable state to the calling terminal, and the flag of the connection request frame is not set, the terminal sets the flag and relays transmission, and then A connection response frame containing information representing connectable terminals is transmitted to the calling terminal, while the destination group name is a group name in which the terminal exists, and the terminal is connected to the calling terminal. Even if it is possible, if the flag has already been set, the connection request frame will be relayed and transmitted as is, and the calling terminal will return to the connection after going around the looped signal transmission path. Based on the flag in the request frame, it is determined whether there is a terminal that can be connected within the terminal group, and the connected terminal is recognized based on the connection response frame. Each terminal in the network checks the above flag in the connection request frame that comes in one cycle, and if there is already a terminal that can connect to the connection request from the calling terminal, it is necessary to send a connection response frame. do not have.

Therefore, the calling terminal and any terminal in the terminal group can be connected by just one frame transmission/reception, and connection request frames are continuously sent from different calling terminals to the same terminal group. If the connection request frame is sent, there will be no delay in responding to the calling terminal that subsequently sent the connection request frame.

Further, in the group name access method of the second invention, the calling terminal transmits a connection request frame including the destination group name as a simultaneous broadcast frame or group circular broadcast, and the calling terminal other than the calling terminal that receives the connection request frame The terminal determines whether the destination group name is the group name of the terminal group in which the terminal exists, and as a result, it is the group name in which the terminal exists, and the terminal is the calling terminal. in a connectable state,
If the address of another terminal is not added to the connection request frame, the terminal adds the address of the terminal to the connection request frame and relays it, while the destination group name indicates that the terminal exists. Even if the terminal is a group name and the terminal can connect to the calling terminal, if the address of another terminal has already been added to the connection request frame, the connection request frame will be relayed as is. The calling terminal determines whether or not the address of another terminal is added to the connection request frame returned after going around the loop-shaped signal transmission path, and determines which terminals are connectable within the terminal group. At the same time, the connected terminal is recognized by the address of the other terminal added to the connection request frame, so each terminal in the terminal group can respond to each incoming call. By checking the addresses of other terminals added to the connection request frame from the calling terminal, it is possible to avoid responding to a connection request from an individual calling terminal if a terminal that can connect already exists. Tomoyoshi.

Therefore, if it is possible to connect between terminals by just one frame transmission from each calling terminal, and if connection request frames are sent consecutively to the same terminal group from different calling terminals, In addition, there is no delay in responding to a calling terminal that later sends a connection request frame.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of a network system according to the present invention, FIG. 2 is a diagram showing an example of the frame structure and frame contents in the above embodiment, and FIG. 3 is a diagram showing an example of an embodiment different from the above embodiment. It is a figure which shows an example of the structure of the FS part, and the content of a frame in an example. l... Signal transmission path, 11... Terminal (a), 1
2...Terminal (b), 2■...Printer (A)
), 22... Printer (B), 23... Printer (C).

Claims (2)

[Claims] (1) A network system in which a plurality of terminals are accommodated in a loop-shaped signal transmission path, and one or more terminals among the plurality of terminals constitute a terminal group, from a terminal that does not belong to the terminal group to the above terminal. In a group name access method in which an arbitrary terminal within a group is accessed using a group name given in advance to the terminal group, the calling terminal is capable of receiving a destination group name representing the group name of the terminal group. A connection request frame containing a flag indicating that a terminal exists is transmitted as a simultaneous broadcast frame or a group broadcast, and when terminals other than the calling terminal receive the connection request frame, they transmit the connection request frame. determines whether or not the destination group name included in the above is the group name of the terminal group in which the terminal exists, and the destination group name is the group name in which the terminal exists, and the terminal is the one making the call. If the terminal is in a connectable state and the flag included in the connection request frame is not set, the terminal sets the flag in the connection request frame and relays transmission, and then connects to the connectable terminal. A connection response frame containing information representing the calling terminal is sent to the calling terminal, while the destination group name is the group name in which the terminal exists, and the terminal is in a state where it can connect to the calling terminal. Even if the flag included in the connection request frame is already set, the connection request frame is relayed as is, and the calling terminal goes around the loop signal transmission path and returns. Based on the flag in the connection request frame, it is determined whether there is a connectable terminal in the terminal group, and the connection response frame sent from a terminal connectable to the calling terminal is determined. A group name access method characterized by recognizing a connected terminal based on. (2) A network system in which a plurality of terminals are accommodated in a loop-shaped signal transmission path, and one or more terminals among the plurality of terminals constitute a terminal group, from a terminal that does not belong to the terminal group to the above terminal. In a group name access method in which an arbitrary terminal within a group is accessed using a group name given in advance to the terminal group, the calling terminal requests a connection that includes a destination group name representing the group name of the terminal group. The frame is transmitted as a simultaneous broadcast frame or a group broadcast frame, and when a terminal other than the calling terminal receives the connection request frame, the destination group name included in the connection request frame indicates that the terminal exists. If the destination group name is the group name in which the terminal exists, and the terminal is connectable to the calling terminal, and other If the terminal address is not added to the connection request frame, the terminal adds the terminal address to the connection request frame and relays it, while the destination group name is the group name in which the terminal exists. And even if the terminal is in a state where it can connect to the calling terminal, if the address of another terminal has already been added to the connection request frame, the connection request frame will be relayed as is. , The calling terminal determines which terminals are connectable within the terminal group depending on whether the address of another terminal is added to the connection request frame that has returned after going around the loop-shaped signal transmission path. A group name access method characterized in that, while determining whether there is a terminal, a terminal to be connected is recognized based on the address of the other terminal added to the connection request frame.