KR950001520B1 - Signalling terminal group bus communication protocol of message transfer part using common channel signalling no.7 - Google Patents

Abstract

The protocol supports the efficiency and confidentiality of protocol between message processing board and signalling terminal board, and communicates with 16 slaves at the STG-bus. The protocol includes the afformative response (DATA-ACK), the non-acknowledge response (DATA-NAK), the data request (DATA-REQ), the data display (DATA-IND), the receiving state request (SEQ-REQ), the receiving state response (SEQ-REP), the procedure number initialization (RST-CMD), thd procedure number initialization response (SEQ-REP), the slave monitoring (ANS-PKT), and the primitive of the response (NSB-PKT).

Description

Signal line group bus communication protocol of common line signaling system

1 is an STG-bus configuration diagram applied to the present invention.

2 is a block diagram of a protocol data frame applied to the present invention.

3 is a schematic diagram of protocol primitives applied to the present invention.

4 to 14 are flowcharts for explaining the operation of the present invention.

The present invention provides a message handling board (MHB) and a level in order to provide a level 2 connection function among the level 3 functions of a common line signaling method (CCS No. 7) message transfer part (MTP). The present invention relates to a communication protocol applied to a signal terminal group bus (STG bus), which corresponds to a communication bus between two signal terminal boards.

An object of the present invention is to provide a protocol for efficient and reliable high speed communication in a communication bus between a message processing board and a signaling terminal board (STB).

In the STG-bus operation scheme applied to the present invention, if a round robin arbitration is applied to improve bus efficiency, the master can improve data transmission to the slave, but the slave has a self-order. In this case, it is possible to transmit data to the master only when the data is transmitted. Therefore, the transmission opportunity between the master and the slave is imbalanced, which makes it difficult to apply a protocol for error control and recovery of the transmitted / received data.

The present invention applies the following protocol to achieve the above object and to solve the problems appearing when applying the error control and recovery protocol.

In the present invention, a transmission / reception sequence number is applied for error control and recovery, and the transmission sequence number is applied only to a data frame (DATA-REQ, DATE-IND). When sending data from the master to the slave, a window mechanism can be used to continuously send a response without acknowledgment or NAK. In other words, the window size is the number of retransmission buffers in the case of the master, and the slave is 1. When a certain number of data is received from the master without transmitting data from the slave to the master or NAK, which is a reception error response, the slave sends an ACK including the receiving sequence number in its reception state to the master. The master always sends a reception response for the data received from the slave since the slave window size is 1. However, in order to reduce the number of reception responses, the slave or the master always includes the reception sequence number, which is the next data frame number, in the transmitted data, ACK or NAK frame. That is, when there is data to be transmitted at the time of transmitting the ACK, the ACK frame can be replaced by notifying the reception status of the own station in the reception sequence number of the transmission data. The window size applied to the master is determined in consideration of the speed of the STG bus, the error detection time of the slave, the number of slaves currently available, and the number of retransmission buffers of the master.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention;

First, the STG bus structure to which the present invention is applied through FIG. 1 will be described.

The STG-Bus provides 1 MPbs full-duplex communication and employs round-robin arbitration by hardware. The STG bus is a serial bus that can accommodate up to 16 signal terminals. It has five signals: transmit data bus (STXD), receive data bus (SRXD), transmit and receive clock (SCLK), bus occupancy signal (SAST) and transmit. It consists of a signal of the synchronization signal SFRS, and a message processing board which is a master of the bus supplies a clock and a synchronization signal to a signal terminal which is a slave. The data bus has separate transmission and reception for full duplex communication. In STG-bus, in order to increase the transmission capacity of the master, the master is configured not to include the master in arbitration, but only to the slave. Therefore, the data from the master to the slave can always be transmitted. In the slave to the master, the data is transferred when it is in its own order.

2 is a data frame diagram used in the STG-bus protocol. In the drawing, 21 and 29 are flags indicating the beginning and end of a frame and used as a signal for frame synchronization between a transmitter and a receiver. . The receiving side identifies the start and end of the frame by detecting this flag.

Reference numeral 22 denotes a reception address unit, which assigns an address of a counterpart that receives a frame when the frame is constructed.

Every processor connected to the bus has its own unique address, which allows point-to-multipoint connections. The address # 11111111 is a global address and is used for frame construction that all stations (signal terminals) can receive at the same time. 23 constituted after the receiving address section is used to distinguish the type of frame by the frame primitive COMTY. The 24 constructed after the primitive is used as a delimiter for determining the frame transmitting side with the transmission address section. The 25 configured next to the transmission address indicates the transmission sequence number (N. (S)) of the frame, and the transmission side writes the sequence number of the information frame to be transmitted in the transmission sequence number byte. 26 indicates a receiving sequence number of the frame, and transmission of N (R) means that a frame up to N (R) -1 is normally received. The sequence numbers N (S) and N (R) in the frame format are independent of one another.

The sequence number applied in the present invention is used as 256 cycle numbers from 0 to 255, and after 255, the sequence returns to zero. For the sequence number, the transmission sequence number N (S) is effectively applied only to data frames having primitives DATA-REQ and DATA-IND.

An information field 27 formed after the reception sequence number contains the data contents to be transmitted. The content of the data is not related to any bit pattern, and a frame or the like used only by protocol control has no information. The frame error detection unit (GRC) 28 formed after the information unit is composed of two bytes, and the frame for which the error has been detected is discarded because the receiving station detects an error for the received frame.

In FIG. 2, the frame structure of the protocol applied to the present invention has been described.

Next, FIG. 3 illustrates the function of each primitive COMTY indicating the type of frame among the frame elements described in FIG. There are 11 types of primitives used in the present invention, and the receiving side distinguishes the types of primitives by the value of the primitive. The transmission data request (DATA-REQ) is a primitive indicating data transmission from the master to the slave, and the transmission data indication (DATA-IND) is a primitive indicating data transmission from the slave to the master. The send and receive sequence numbers of DATA-REQ and DATA-IND frames must be filled in.

Receive data acknowledgment (DATA-ACK) is a primitive that is used to send a positive acknowledgment to the sender when the received frame is correct and ready to receive the next frame. In the case of an acknowledgment, the frame reception number to be received next is written in N (R) of the frame format. However, the method of acknowledgment is slightly different between the master and the slave, i.e., when the master receives the data (DATA-IND) from the slave, the acknowledgment should be acknowledged for each received frame. Since only the slave receives data from the master, it only transmits to the master when the slave receives a certain number of data frames.

Received data negative response (DATA-NAK) is a primitive sent when the receiver detects an N (S) sequence error during frame transmission and is used by the master and slave for the same purpose. In response to a negative response, a NAK frame is transmitted, and a retransmission of an information frame indicated by N (R) of the NAK frame can be requested. At this time, the transmitting side retransmits the information frame designated by N (R).

The sequence initialization command (RST-CND) requires the master or slave to initialize the transmission status variables (V (S) and reception status variables (V (R)) to a specific number for self-management of the transmission and reception numbers. It is a primitive and the response (RST-REP) is the frame that sends the response.

The reception status request (SEQ-REQ) and the response (SEQ-REP) fail to receive the receiving sequence number N (R) from the slave, and if the master transmission buffer is not updated, the slave side is sent to the slave for management of the retransmission buffer. It is a primitive (SEQ-REQ) that requires N (R), and the slave responds with SEQ-REP. If there is no response, it is treated as an abnormal slave group. The ANS-PKT is a primitive for periodic checks by the master, but the ANSB-PKT is a primitive indicating the response, and a slave that has not responded more than three times is treated as an abnormal slave group.

The loop packet (LPBK-PKT) is a primitive indicating the frame to be used for the self loop test of the STG-bus.

When one or more bits of the COMTY byte in the frame format occur when there is a situation in which the master or slave cannot temporarily receive the information frame due to internal constraints such as insufficient reception buffer for notification and recovery of an abnormal condition. Set (# 1) to notify the other side of the unacceptable status, and reset the F bit of the COMTY byte (# 0) to request retransmission (receive enabled). The frame receiving side with an F bit of 1 should stop transmitting in the information frame as soon as possible.

The frame structure and primitives used in the present invention have been described above, and the following describes the transmission state variable V (S) and the reception state variable V (R) required for performing the protocol control procedure. The master and the slave have a transmission state variable V (S) and a reception state variable V (R) for self management of the transmission / reception sequence numbers. V (S) is a variable used to determine the N (S) of the message and indicates the frame N (S) to be sent next. The transmitter adds 1 to V (S) every time a frame is sent. The receiving side adds 1 to V (R) when N (S) of the received data frame normally takes a frame equal to V (R) which is a self-managed variable of the sequence number. V (R) is used for error determination of the transmission sequence number. When transmitting an information frame, the values of V (S) and V (R) are written into N (S) and N (R) of the control unit. V (S) and V (R) are initialized to zero during initial link setup. A master connected to 16 slaves has 16 V (S) and V (R).

Next, the operation of the embodiment of the present invention will be described.

4 to 14 show a flow chart for explaining the protocol control procedure. First, a case of receiving a frame whose primitive is an acknowledgment (DATA-ACK) will be described with reference to the flowchart of FIG. First, it checks whether the received sequence number N (R) of the received frame is the sequence number stored in the retransmission buffer (40), and determines whether it is valid (41), and performs the retransmission buffer update procedure only when the inspection result is valid. After that (42), the procedure ends. In the retransmission buffer update procedure, the transmission data up to N (R) -1 is normally received at the receiving end. Therefore, the frame pointer of the retransmission buffer and the number of buffers to be acknowledged are updated. If N (R) is not valid, initialize the transmission status variable, transmission buffer and counter (43), and send the current transmission status variable to N (S) using RST-CMD among primitives and send it to the other side. A request is set for the request (44), and the procedure upon receiving the ACK is terminated.

A case of a negative response (DATA-ACK) will be described with reference to the flowchart of FIG. The negative acknowledgment is a retransmission request signal due to the reception error of the other party. The processing procedure is the same as the processing procedure in the case of a positive acknowledgment (40 to 44), and the difference is when the receiving sequence number N (R) of the frame is valid (51). Only the procedures for updating the retransmission buffer, the transmission buffer and the transmission status variable according to the reception sequence number N (R) are added (52, 53). That is, the transmission buffer is a buffer pointer indicated by N (R), and the transmission state variable is updated to N (R) (53). That is, the transmission of the next data frame (DATA-REQ, DATA-IND) should be transmitted from the data frame corresponding to N (R).

Referring to the flowchart of FIG. 6, the case where the primitive receives a data premise of DATA-REQ or DATA-IND will be described. First, a sequence error check of the transmission sequence number N (S) of the received frame is performed (60). The error check of N (S) checks whether the transmission sequence number N (S) of the information frame received by the information frame receiving side is equal to the reception state variable V (R) held by the receiving side (61). If sent normally, the two values match. If it is not the same, then N (S) is a sequence error. When the information frame is normally received, 1 is added to the reception state variable V (R) of the host (62), and a DATA-ACK frame for receiving the data frame should be sent to the counterpart, and an ACK transmission request is determined for this purpose (63). . If there is an N (S) sequence error, the V (R) value is not updated, and the corresponding frame is discarded (65). At this time, the N (R) byte of the NAK frame is sent with the next receiving sequence number to be received. 66). ACK frame transmission has a slight difference between the characteristics of the bus between the slave and the master, and the master should always send an ACK to every slave in the data frame (DATA-IND) .The slave side transmits data or received error to the master. ACK should be sent when a certain number of data frames (DATA-REQ) are received from the master without any NAK. However, if there is a data frame to be transmitted in order to reduce the number of ACK frame transmission, it is not necessary to transmit. When the ACK sending request setting is completed, using the received N (R) to update the retransmission buffer, perform the update procedure of the retransmission buffer using the same procedure (40 to 44) as when receiving the ACK (64). Quit.

A case in which the primitive receives a frame whose primitive is the transmission / reception sequence number initialization response (SEQ-REP) will be described with reference to the flowchart of FIG. When the SEQ-REP frame is received, the initialization procedure of the transmission / reception state variable is performed (70), the initialization of the transmission buffer and counter (71) is completed, and the processing procedure is terminated.

Referring to the flowchart of FIG. 8, when the primitive receives a frame whose primitive response (ANSB-PKT) is a periodic answer test (ANSB-PKT), an answerback response flag is set (80) for anomalous state processing, and the number of non-responses is set. After the reset procedure is zero (81), the processing procedure ends. The reception of ANSB-PKT is limited to the master.

Referring to the flowchart of FIG. 9, when the primitive receives a frame composed of the periodic check of the slave (ANS-PKT) primitive, the check response (ANSB-PKT) of the check response to inform the master that the receiving processor is in a normal operation state. A frame must be constructed (90) and sent to the master (91). Receive ANS-PKT is for slave only.

In FIG. 3, the processing procedure for each primitive when a single data is normally received has been described. In FIG. 10, when a reception error occurs due to an electrical error when receiving data, the received data is discarded (100). Terminate the procedure of the city.

Referring to the flowchart of FIG. 11, if there is a data transmission request with a DATA-REQ and DATA-IND primitive, first, if the bus is in a transmittable state, a frame to be transmitted is configured according to a predetermined data format (110), and a retransmission buffer and The update procedure of the transmission buffer is performed (111, 112). Next, 1 is added to the transmission state variable V (S), the number of transmission buffers, and the number of retransmission buffers, and the buffer pointer is updated by one frame (113). Then, the data frame transmission command is executed and the procedure is terminated. When sending data from the master to the slave, the maximum frame size that can be transmitted continuously without acknowledgment is 크기 window size-1 ＂because the window size, which is the number of frames that can be transmitted without ACK and NAK, is greater than 1. In other words, N (S) equal to N (R) of the last received information frame plus “window size-1” cannot be transmitted even if ready for transmission. The window size is limited by the system's capabilities. On the contrary, in case of slave to master, the window size is 1, so the frame cannot be continuously transmitted, and the next frame can be transmitted after confirming the reception response from the master.

FIG. 12 is a flowchart of a procedure of performing a data-ACK frame transmission request. Upon receiving the transmission request, first, it is checked whether there is a data frame to be sent to the other party (120), and if there is data, releases the data-ACK transmission request (124). The process ends. However, if there is no data to be transmitted, a frame is formed by putting the reception state variable of the local station into the N (R) bytes of the ACK frame (121), and after releasing the ACK transmission request (122), for transmitting the ACK frame to the counterpart Perform the command (123) and terminate the procedure.

Figure 13 is a flow chart of the execution procedure when sending a DATA-NAK frame.When receiving a sending request, the receiving state variable of the local station is put in N (R) bytes of the NAK frame for retransmission request (130), and the NAK sending is performed. After releasing the request (131), a command for transmitting the NAK frame to the counterpart is performed (132), and the procedure ends.

FIG. 14 is a flow chart of the procedure of SEQ-RST frame transmission request.When receiving the transmission request, the frame is composed by putting the transmission status variable of its own station in the N (S) byte of the frame to initialize the sequence number (140). After releasing the request for transmission (141), a command for transmitting the frame to the other party is performed (142) and the procedure ends.

When sending the data described above, only the data frame transmission request such as DATA-REQ and DATA-IND applies the transmission sequence number, and in order to inform the other station of the reception status of the local station, the reception status variable of the own station in the reception sequence number N (R). Send with V (R) value. The transmission method of the data frame used for protocol control other than DATA-REQ and DATA-IND is the same as above. The difference is that the application of the transmission sequence number and the update procedure of the transmission buffer are not performed. In addition, since the slave window size is 1 for error recovery on the slave side, the next data can be sent after confirming the reception response from the receiving side. In order to solve this problem, the slave sends an information frame to the master, and then operates a timer for acknowledgment from the master. start) and recovery operation is started by timeout if there is no response even after a predetermined time elapses.

The present invention configured and operated as described above has the following effects.

In the present invention, the transmission and reception are separated according to the hardware structure of the bus, and 16 slaves are connected to one master to perform point-to-multipoint communication, and the error recovery control is performed in an adverse structure in which transmission and reception are imbalanced. In order to recover the reception error by applying the sequence number when transmitting / receiving the data frame, the window mechanism is applied when the data is sent to the slave to improve the data transmission capability of the master, and in case of receiving the acknowledgment frame, It is possible to reduce the number of ACKs sent by inserting the receiving sequence number in the receiving state.

As described above, by applying the above protocol to the STG-bus, communication with up to 16 slaves can be efficiently and reliably provided.

Claims (11)

An STG-bus communication protocol of a common line signaling message transfer unit; Acknowledgment (DATA-ACK), Negative Response (DATA-NAK), Data Request (DATA-REQ), Data Display (DATA-IND), Receive Status Request (SEQ-REQ), Receive Status Response (SEQ-REP), It consists of primitives of sequence number initialization (RST-CMD), sequence number initialization response (SEQ-REP), slave periodic check (ANS-PKT), and its response (ANSB-PKT). Message transmission unit STG-bus communication protocol, characterized in that consisting of communication procedures applied between the board and one master board. The method of claim 1, wherein the procedure for receiving an acknowledgment frame first checks whether the received sequence number N (R) of the received frame is a sequence number stored in the retransmission buffer (40), and determines whether it is valid (41). ), After the retransmission buffer update procedure is performed only when the test result is valid (42), the first step of terminating the procedure, and, if N (R) is not valid, A second step of performing initialization (43), using RST-CMD among primitives to set the current transmission state variable to N (S), requesting for transmission to the other party (44), and ending the procedure at the time of receiving the ACK; And a communication protocol. The processing procedure according to claim 1, wherein the processing procedure upon receiving the negative acknowledgment frame includes retransmission buffer transmission buffer and transmission status variable according to the reception sequence number N (R) when the reception sequence number N (R) of the frame is valid (51). A communication protocol comprising an update procedure. The method of claim 1, wherein upon receiving the data request and the data display frame, the processing procedure first checks an error of the transmission sequence number N (S) of the received frame (60), and checks the error of the N (S) information frame. The receiving side checks whether the transmission sequence number M (S) of the information frame is the same as the receiving state variable V (R) held by the receiving side (61). Add 1 to (R) (62), and send a DATA-ACK frame for data frame reception to the other side. For this, set ACK sending request (63). First step, V (N) (R) value is not updated, and the corresponding frame is discarded (65). At this time, the second (S) step of transmitting the received order number to be received next to the N (S) byte of the NAK frame (66) is provided. Communication protocol, characterized in that. The method according to claim 1, wherein when a frame having a transmission / reception sequence number initialization response (SEQ-REP) is received as a primitive, when the SEQ-REP frame is received, an initialization procedure of a transmission / reception state variable is performed (70). And (71) initializing the counter and terminating the processing procedure. 2. The method of claim 1, wherein when a frame having a response (ANSB-PKT) as a primitive in the periodic answer test is received, the answer back response complex is set (80) for an abnormal state processing, and the number of non-responses is returned to zero. And after completion of the set procedure (81), terminating the processing procedure. The method according to claim 1, wherein when receiving a frame composed of a periodic check (ANS-PKT) primitive of the slave, a check response (ANSB-PKT) frame is configured to inform the master that the receiving processor is in a normal operation state (90). And (91) sending to the master. The method according to claim 1, wherein if there is a data transmission request with a DATA-REQ or DATA-IND primitive, first, if the bus is in a transmittable state, a frame to be transmitted is configured according to a predetermined data format (110), and a retransmission buffer and a transmission are performed. After updating the buffer (111, 112), and then adding 1 to the transmission state variables V (S), the number of transmission buffers and the number of retransmission buffers, and updating the buffer pointer by one frame (113), And a step of executing a sending command of the data frame and ending the procedure. The method of claim 1, when a request for sending a data-ACK frame is received, first, whether there is a data frame to be sent to the other party is checked (120), and if there is data, the data-ACK transmission request is released (124). When there is no data to be transmitted, the frame is composed by putting the reception state variable of the host in the N (R) byte of the ACK frame (121), and after releasing the request for sending ACK (122), the ACK frame is sent to the other side. And performing an instruction to terminate the procedure and terminating the procedure. The method according to claim 1, wherein when a transmission request is received for a DATA-NAK frame, a frame is formed by putting a reception state variable of the local station into N (R) bytes of a NAK frame for retransmission request (130), and a NAK transmission request is made. And releasing (131), performing a command for transmitting the NAK frame to the counterpart (132) and terminating the procedure. The method according to claim 1, wherein upon receiving a request for sending a SEQ-RST frame, a frame is constructed by inserting a transmission state variable of the own station into N (S) bytes of the frame for initialization of a sequence number (140) and canceling the request for sending a frame. And (141), performing a command to send the frame to the other party (142) and terminating the procedure.