JPH0591117A - Secondary station initial setting system in sdlc communication system - Google Patents

Abstract

PURPOSE:To properly set the operation after initial setting by inserting a secondary station state data at the reception of a command to an affirmative response with respect to the initial setting command and returning the response to a primary station. CONSTITUTION:When an I command from, e.g. a primary station 1 does not normally reach a secondary station 2i due to a fault of a communication line in the loop communication state, the secondary station 2i does not execute return of an improper RR response. Thus, the primary station 1 recognizes the occurrence of a communication error, releases a loop state and returns an SIM command to the secondary station 2i. In this case, the secondary station 2i inserts a secondary station state data representing that its own station is busy and in the state of awaiting the I command to a UA response and returns the result to the primary station 1. Upon the receipt of the UA response, the primary station 1 executes the communication test and restores the state to the loop state and recognizes that the secondary station 2i is busy and restarts the communication in a sequence in matching with the state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to SDLC (Synchronous
Data Link Control) This is a method for initializing the secondary station when a communication path failure or an internal failure of the secondary station occurs in a communication system.

[0002]

2. Description of the Related Art There is SDLC as a protocol of a data link control layer, and there is a network that employs this SDLC to perform loop communication. For example, communication between various modules in a multiprocessor system is shown in FIG.
SDLC loop communication as shown in FIG.

In SDLC loop communication, at least one primary station 1 having a responsibility for a data link for managing a loop and a secondary station, and a plurality of secondary stations 20 to 2n form a loop. Are connected, and through such a loop, from the primary station 1 to any secondary station 2i (i is 0 to
n), and data communication from any one of the secondary stations 2i to the primary station 1. Data is transmitted and received in units of frames, and the primary station 1 to the secondary station 2i
To the primary station 1 is called a response, and the frame from the secondary station 2i to the primary station 1 is called a response.

A plurality of secondary stations 20 connected in a loop form
Since one in 2n is involved in communication with the primary station 1, each 2
The next station naturally needs a unique address. The process of setting such an address or the like in the secondary station 2i is performed when the loop is initially set or when a failure occurs in the communication path or the secondary station.

FIG. 3 is a sequence diagram when the loop is initialized. As shown in FIG. 3, the primary station 1 and one secondary 2i are connected at a ratio of 1: 1, and an initial value mode set frame (initial setting command: hereinafter referred to as SIM command) is sent to the primary station 1 To the secondary station 2i to cause the secondary station 2i to execute initialization of addresses and the like, and after this execution, the secondary station 2i sends a positive response to the primary station 1 as a non-sequence response frame (acknowledgment response: UA (Called a response). When the primary station 1 receives this UA frame, it proceeds to the initialization process for the next secondary station, and all the secondary stations 2
When the initial setting process for 0 to 2n is completed, all 2
The next stations 20 to 2n are connected in a loop to start loop communication.

FIG. 4 shows a frame format of a SIM command and a UA response transmitted and received between the primary station 1 and a certain secondary station 2i in such an initialization process. The SIM command and the UA response naturally follow the SDLC frame format. As shown in FIG. 4A, the SIM command includes a start flag sequence, an address field, a control field, an information field, a frame check sequence and an end flag sequence, and the control field indicates that the frame is a SIM command. Data has been inserted. As shown in FIG. 4B, the UA response includes a start flag sequence, an address field, a control field, a frame check sequence, and an end flag sequence, and data indicating that the frame is a UA response is inserted in the control field. Has been done.

The SIM command is used when the primary station sets or resets the operation mode of the secondary station. At the time of this initialization processing, since the address unique to each secondary station 2i is not set in the secondary station 2i, S
“FF” is inserted in the address field of the IM command, and initial values such as set addresses are inserted in the information field. When the secondary station 2i receives the SIM command,
Read and set the address of your own station from the information field.

The UA response is used to indicate that the secondary station 2i has accepted the SIM command, and the secondary station 2i transmits it to the primary station 1.

By the way, the initialization processing for the secondary station 2i is performed not only at the start of the loop communication as described above, but also when the communication channel failure or the secondary station failure occurs as described above. Be done. The setting process in this case is also basically performed by exchanging the SIM command and the UA response.

That is, in the SDLC loop communication state, when a communication error occurs due to a failure in the secondary station 2i or the communication path, the primary station 1 stops the loop communication, and the secondary station 2i 1: 1 to establish a connection, and perform the initial setting process for the secondary station 2i which exchanges the SIM command and the UA response described above. After this, a communication test is further performed. If the communication test is normal, the loop connection state is restored again and loop communication is restarted.

[0011]

The cause of the communication error is
In the case of a temporary failure due to noise or the like, the normal loop communication state can be restored by the series of initial setting procedures described above.

However, when the cause of the communication error is a failure inside the secondary station 2i, there may be a problem in the above-described series of initial setting procedures. When a failure occurs inside the secondary station 2i, the secondary station 2i may activate the reset routine. However, even if the secondary station 2i tries to activate the reset routine, the primary station 1 transmits the SIM command and performs the initial setting, and the secondary station 2i simply returns a UA response. Therefore, if the communication test is normal, the primary station 1 shifts to the loop communication state regardless of whether the secondary station 2i has activated the reset routine. However, different sequences are required depending on whether the reset routine is activated or not. That is, when the reset routine is not activated, the data transmitted after being normally transmitted to the secondary station may be transmitted, but when the reset routine is activated, the data accurately transmitted to the secondary station may be transmitted. However, it is necessary to transmit the data from the beginning. Therefore, when loop communication is restarted, a sequence error may occur between the primary station and the secondary station.

In order to solve such an inconvenience, the primary station 1 transmits an information command (hereinafter, referred to as an I command) to the secondary station 2i to request the return of the secondary station state and the secondary station 2i.
May send back the status of the secondary station to the primary station 1 as a receivable response (hereinafter referred to as RR response). However, there is a problem in that the time for the initial setting process is extended by the amount of the exchange of the I command and the RR response.

The present invention has been made in consideration of the above points, and the primary station can know the state of the secondary station during the initialization process. An object of the present invention is to provide a secondary station initial setting method in an SDLC communication system that does not last for a long time.

[0015]

In order to solve such a problem, the present invention comprises a primary station which is responsible for a data link and at least one secondary station managed by this primary station. , In an SDLC communication system adopting SDLC as a data link control layer protocol, in response to an initialization command sent by the primary station,
Information indicating the state of the secondary station at the time of receiving the initial setting command is inserted in the positive response output from the secondary station.

[0016]

In the present invention, the primary station can immediately know the secondary station state from the information indicating the secondary station state at the time of receiving the initial setting command, which is inserted in the acknowledgment response. Therefore, with this secondary station information, an appropriate communication sequence can be selected when loop communication is resumed, and the occurrence of sequence errors can be prevented.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. This embodiment is characterized in that the format of the UA response is changed. Therefore, the communication sequence at the time of initial setting processing of the secondary station 2i is also different from the conventional one.

First, referring to FIG. 5, U according to this embodiment is used.
The frame format of the A response will be described. Figure 5
As shown in, the UA response of this embodiment has the same start flag sequence, address field, control field, frame check sequence, and end flag sequence as the conventional one, and additionally has an information field. In the case of this embodiment, data representing the secondary station state is inserted in the newly provided information field. That is, the secondary station state data indicating that the local station is communicating and is in the I command waiting state (state where the reset routine is not activated), or the initial station is reset and the SIM command is received. Secondary station status data indicating that it has been waiting is inserted.

FIGS. 6 and 7 respectively show primary stations 1 and 2 utilizing a UA response with a new format.
It is a flow chart which shows a processing procedure of next station 2i.

The processing on the primary station 1 side will be described first with reference to FIG. When the secondary station initial setting process is started, the secondary station 2
After executing a 1: 1 connection with i, a SIM command is transmitted (steps 100-102). After that, it is judged whether or not the UA response is returned (step 1
03). If it has not been returned, it is determined whether or not the SIM command is retransmitted (whether or not the SIM command has been retransmitted a predetermined number of times), and if retransmitted, the process proceeds to step 102 described above. When further resending is unnecessary, an initial setting NG process is performed to display a message indicating that the initial setting cannot be performed (steps 104 and 105). On the contrary,
When the UA response is returned, a communication test is executed (step 106), a series of initial setting processing is ended, and the processing proceeds to loop communication processing from step 107 onward.

In the loop communication process, a loop communication start process such as setting a loop connection state is first performed (step 10).
7) After that, the I command and the polling (transmission right) are transmitted (steps 108 and 109). Here, the I command is transmitted based on the secondary station status data inserted in the received UA response. For example, if the secondary station is reset, even if there is data that has been transferred due to a communication error and transfer has been interrupted, transfer is performed using the I command from the first data.
If the secondary station has not been reset, even if the transfer is interrupted due to a communication error, the untransferred data is transferred by the I command.

Then, it is judged whether or not the RR response or I response from the secondary station 2i is received (step 110). If not received, it is determined whether or not the I command is retransmitted (whether or not the I command is retransmitted a predetermined number of times).
If no further resending is required, it is detected that a communication error has occurred, the loop communication is stopped, and the secondary station initial setting process is started (steps 111 to 11).
3). On the other hand, when the RR response or the I response is returned, the RR command is transmitted to the secondary station 2i, and then the I command transmitting process is performed (step 114).

Next, the processing on the secondary station 2i side will be described with reference to FIG. In the secondary station initial setting processing, first, the SIM command is waited, and when this is received, the UA response in which the own station state obtained by judging the state of the own station is inserted is returned to the primary station 1 (steps 200 to 203). ). Then, a communication test is performed (step 204). Thus, when the series of initial setting processes are completed, the process proceeds to the loop communication process after step 205.

In the loop communication process, a loop communication start process such as setting a loop connection state is first performed (step 20).
5) After that, reception processing of the RR command or I command transferred from the primary station 1 is performed (step 20).
6).

Then, it is confirmed whether or not the SIM command has been transferred (step 207). If it has been transferred, the process returns to the above-mentioned step 202. On the other hand, if it has not been transferred, it waits for the reception of polling and 1
Send the RR response or I response to the next station 1,
The process returns to the waiting state for receiving the I command or the RR command from the primary station 1 (steps 208 and 209).

FIG. 1 shows a primary station 1 which operates as described above.
And an example of a communication sequence executed by the secondary station 2i. FIG. 1A shows a sequence when a communication error occurs due to a communication path failure.
(B) shows a sequence when a communication error occurs due to a secondary station failure.

First, the communication sequence of the resetting process at the time of communication path failure will be described with reference to FIG.

In the loop communication state, for example, the primary station 1
When the I command from the above does not normally reach the secondary station 2i due to a communication path failure, the secondary station 2i outputs an inappropriate RR response or does not return the RR response. As a result, the primary station 1 recognizes that a communication error has occurred (S1), cancels the loop state, and returns to SI.
The M command is transmitted to the secondary station 2i (S2). At this time, the secondary station 2i inserts the secondary station status data indicating that it is in communication and waiting for an I command into the UA response and returns it to the primary station 1 (S3). Upon receiving this UA response, the primary station 1 executes the communication test and returns to the loop state, then recognizes that the secondary station 2i was in communication and restarts the communication in a sequence suitable for it. (S4).

Next, the communication sequence of the resetting process at the time of internal failure of the secondary station will be described with reference to FIG.

In the loop communication state, when a failure occurs inside the secondary station 2i, the reset routine is activated and the initial state is set. Therefore, the secondary station 2i receives a global command (for example, SIM) whose address is "FF". Only commands) will be accepted. In this state, for example, even if the primary station 1 sends an I command to this secondary station 2i, the address is not valid, so the secondary station 2i
The return of the R response is not executed (S10). Since the RR response is not returned, the primary station 1 recognizes that a communication error has occurred (S11), releases the loop state, and sends a SIM command to the secondary station 2i (S2).
1). At this time, the secondary station 2i inserts the secondary station state data, which indicates that it is in the reset initial state and was in the state of waiting for the SIM command, into the UA response to the primary station 1. It is returned (S13). The primary station 1
When this UA response is received, after the communication test is executed and the loop state is returned to, the secondary station 2i recognizes that it is in the initial state and restarts communication from the beginning (S14).

Therefore, according to the above embodiment, the secondary station 2
i is the UA response to the SIM command and SI
Since the secondary station status data at the time of receiving the M command is inserted and returned to the primary station 1, the primary station 1 does not exchange the I command and the RR response.
The state of the next station 2i can be recognized, and the operation after initial setting can be appropriately selected. As a result, it is possible to prevent a sequence error from occurring in the loop communication state restarted after the initial setting.

The present invention can be applied to various network systems. Further, not only the SDLC loop communication but also the SDLC communication of other connection forms can be applied.

[0033]

As described above, according to the present invention, the secondary station status data at the time of reception of the command is inserted into the positive response to the initial setting command and returned to the primary station. The primary station can recognize the state of the secondary station without sending and receiving other commands and responses, can select the operation after the initial setting properly, and can perform the sequence in the loop communication state restarted after the initial setting. It is possible to prevent an error from occurring.

[Brief description of drawings]

FIG. 1 is a communication sequence diagram illustrating a secondary station initial setting process when a failure occurs according to an embodiment.

FIG. 2 is a block diagram showing an SDLC loop configuration.

FIG. 3 is a communication sequence diagram showing a secondary station initial setting process at the start of system operation.

FIG. 4 is a format diagram of a conventional SIM command and UA response.

FIG. 5 is a format diagram of a UA response according to the embodiment.

FIG. 6 is a processing flowchart of the primary station according to the embodiment.

FIG. 7 is a processing flowchart of a secondary station according to the embodiment.

[Explanation of symbols]

 1 ... Primary station, 20-20n ... Secondary station.

Claims (1)

[Claims] 1. A primary station which is responsible for a data link, and at least one secondary station managed by the primary station, wherein S is used as a data link control layer protocol.
In an SDLC communication system adopting DLC, in response to an initial setting command sent from the primary station, an acknowledgment response output from the secondary station, information indicating the state of the secondary station at the time of receiving the initial setting command. A secondary station initial setting method in an SDLC communication system, characterized in that