JP2581180B2 - Time information transmission method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Field of the Invention The present invention relates to a high-level data link control procedure (High L
evel Data Link Control (hereinafter abbreviated as HDLC system).
The present invention relates to a time information transmission method for transmitting time information by an LC method.

B. Summary of the Invention The present invention relates to a time information transmission method for transmitting time information according to the HDLC method having a function of retransmitting information when a transmission failure occurs. If the elapsed time is not equal to the set time, it will not be treated as time information and time will not be adjusted, so that even if a transmission failure occurs, between remote control stations and between remote control stations Time adjustment and time management can be performed without errors between controlled sites.

C. Prior Art In recent years, in remote monitoring control, it has been demanded that the monitoring control range be expanded and combined with a computer to increase the speed of response to failures and improve the operation efficiency. Therefore, in order to satisfy the above demand, the HDLC method has recently been adopted as a data transmission method in which the amount and type of information can be easily expanded and computer processing is easy. This HDLC method has the following advantages.

(1) It is possible to confirm whether or not the partner computer is in a receivable state, whether or not the partner computer has received a signal.

(2) When a busy occurs, the transmission of the partner station can be kept until the end.

(3) When a transmission failure occurs, data can be automatically retransmitted, and data loss can be prevented.

(4) Continuous transmission in which a plurality of data are transmitted collectively or full-duplex transmission in which communication is performed simultaneously with each other are possible, so that the transmission time can be reduced.

Here, the International Telegraph and Telephone Consultative Committee (CCITT) divides the responsibilities in the transmission system into levels as shown in Fig. 2. Level 1 has a role of recognizing data, and is described in the transmission format (frame configuration) of the HDLC system shown in FIG. 3, and F (8 bits) for clarifying the start and end of a frame. Flag sequence), A (address section composed of 8 bits) for specifying a station to receive a command and displaying a station that has transmitted a response. Level 2 has a role of controlling an operation command to the partner station as a command and a response to the command as a response, and corresponds to C (a control unit composed of 8 bits). The high level of level 3 or higher is responsible for various types of information, and corresponds to I (information section having no restriction on the bit configuration).

At present, there is also an LSI that performs all the tasks to be performed at the levels 1 and 2 in the HDLC system, and the computer only needs to perform the tasks at level 3 or higher. For this reason, the load on the computer is significantly reduced. Also, the transmission efficiency of the HDLC system is extremely good as compared with other systems. That is, the transmission efficiency is calculated by the number of raw data bits / the number of transmission bits.
In the case of T (cyclic digital transmission) system, In the case of the basic method, In the case of HDLC method, Becomes

Next, data transmission in the HDLC system will be described with reference to FIG. FIG. 4 shows a case where a transmission failure occurs as shown at G during communication between the stations A and B. In the figure, for example, “I · 3 · 4” of “A → B code” is information (I)
Transmission sequence number is 3 and reception sequence number is 4 in the existing frame
, And the number in the column of “transmission data available” indicates the number of sets of remaining data. The data of the transmission failure as G occurs "I · 3 · 4" at time t ₁ does not reach the B station. In A station by +1 the transmission sequence numbers in the next time t ₂ because you do not know the failure "I · 4 ·
4 ”is transmitted. Then, the station B receives the data having the transmission sequence number “2” the previous time, and this time receives the data “I ·
The data "4.4" is received, and the occurrence of a failure is recognized because the transmission sequence number jumps from 2 to 4. Therefore, issues a retransmission request at time t _3, the frame of no I in time t _4, emits a reject signal "REJ · 3". Since “REJ · 3” has been received up to the transmission order number 2 at present, it means that the next transmission of the frame with the transmission order number 3 is expected. Then retransmission request to the A station side at time t ₅ is recognized, the retransmission condition is established,
From time t ₆ to time t ₈ retransmits the data frame having the transmission sequence number 3-5.

As described above, in the HDLC system, communication is performed while confirming the transmission sequence number between the local station and the partner station. Therefore, when a transmission failure occurs, data can be automatically retransmitted, preventing data loss. can do.

D. Problems to be solved by the invention As an example of expanding the type of information in remote monitoring and control, unification among all controlled sites is performed, data of each controlled There are applications to do. For this reason, time information is transmitted from the control center (master station) or from the central control center (general control) to each controlled station (slave station) via the control center (master station), and time adjustment and time management are performed. Is going. When time management of information generated in the controlled place is performed, if a transmission failure or transmission error occurs before and after the transmission of the time information, the time information is automatically retransmitted as described in FIG.
The time difference between the initial transmission and the retransmission directly becomes a time error. This error upsets the time relationship between the events and makes the analysis of the phenomenon impossible.

Hereinafter, the frame transmission state will be described for six cases when a transmission failure occurs. In FIGS. 5 (a) to 5 (f), the squares marked with "time" inside are frames including a time notice signal, and the squares marked "real time" inside include a time execution signal. Is a frame that includes other general data, and the number is a symbol for distinguishing the time relationship. In addition, □ inside which “REJ” is written is a frame including a reject signal. Interval from the time the warning signal to the time execution signal is set in advance in the predetermined time T _1. The time information (time notice signal and time execution signal) is transmitted at a predetermined cycle.
FIG. 5 (a) shows a case where a transmission failure has occurred at the time point of × 2, that is, at the frame transmitted next to the time execution signal (the frame including +1 data). In this case, the upstream side cannot receive the data of +1 and receives the data of +2. Since the transmission sequence number of the data is skipped, it can recognize that there is a transmission failure, and issues a reject REJ to request retransmission. . Then, although not shown, the downstream side performs data retransmission of +1 and +2. Therefore, the case of FIG. 5A has no effect on the time information transmitted before the data of +1.

FIG. 5 (b) shows a case where a transmission failure occurs at the time point of × 3, that is, a frame including the time execution signal. In this case, the uplink side cannot receive the time execution signal, receives +1 data, and can recognize that there is a transmission failure because the transmission sequence number is skipped, and issues a reject REJ to request retransmission. . Then, the downstream side retransmits the time execution signal and the data of +1 and +2 after the transmission frame (+2) in the same time zone as the reject REJ. Since the data has been retransmitted automatically, time T ₂ becomes from time warning signal transmission completion to the transmission time execution signal is completed, the set time T ₁
Will be significantly longer than. For this reason, time adjustment cannot be performed with the first execution time execution signal (at the time of × 3), and time adjustment is performed using the retransmitted time execution signal, resulting in a large time error (E).

FIG. 5 (c) shows a case where a transmission failure has occurred at the time point of × 5, that is, a frame including the time notice signal. In this case, the upstream side receives the time execution signal without receiving the time advance notice signal, and recognizes that there is a transmission failure because the transmission sequence number is skipped.
Issue a REJ to request retransmission. Then, the downstream side retransmits the time advance signal, the time execution signal, and the data of +1 from the transmission frame (+1) in the same time zone as the reject ERJ (the time advance signal and the time execution signal at the time of retransmission are simply are only retransmitted in order, the time difference T ₃ is quite different from the set time T _1). Since the data is automatically retransmitted in this manner, the time cannot be adjusted at the time of transmitting the time transmission signal of the first transmission, and the time is adjusted by the retransmitted time execution signal, resulting in a large time error (E ) Occurs.

FIG. 5 (d) shows a case where a transmission failure has occurred in the frame (frame including data of -1) transmitted immediately before the time notice signal at the time of × 6. In this case, the upstream side cannot receive the data of -1 and receives the time advance notice signal. Since the transmission sequence number is skipped, it can recognize that there is a transmission failure, and the reject REJ
To make a retransmission request. Then, the downstream side retransmits the data of −1, the time advance notice signal and the time execution signal from the time following the time execution signal. In this case, since the transmission sequence number of the first transmission time advance signal is skipped, the signal is not recognized as a normal time advance signal, and therefore, the time adjustment is not performed by the first transmission time execution signal. Since the data is automatically retransmitted in this manner, the time cannot be adjusted at the time of transmitting the first transmission time execution signal, and the time is adjusted by the retransmitted time execution signal, resulting in a large time error ( E) occurs.

FIG. 5 (e) shows a case where a transmission failure has occurred at the time point of × 7, that is, a frame (a frame including -2 data) transmitted two frames before the time notice signal.
In this case, the upstream side cannot receive -2 data-
1 is received and the transmission sequence number is skipped, it can be recognized that there is a transmission failure, and a reject request is issued by issuing a reject REJ. Then, on the down side, time t
_As shown in FIG. ₁₀ , the data of -2, -1 and the time notice signal is retransmitted regardless of the time execution signal transmission timing. And after retransmission time execution signal which has been disabled originated the time t ₁₀ is transmitted. Since the retransmission data is interrupted between the time notice signal and the time execution signal of the first transmission, the time t at which the transmission of the time execution signal should be normally completed.
Long error time from ₁₁ E) so that the time setting is performed at the time t ₁₂ has elapsed.

FIG. 5 (f) shows a case where a transmission failure has occurred at the time point of × 12, that is, a frame including data “2” on the upstream side. In this case, the downstream side cannot receive 2 data but receives 3 data, and since the transmission sequence number is skipped, it can recognize that there is a transmission failure, and issues a reject REJ next to the time notice signal to retransmit. Make a request. Then, the upstream side retransmits the second, third and fourth data after the fourth data. Here, since the reject REJ between times the warning signal and the time execution signal intervened, transmission completion time of the time execution signal t ₁₄ is time t should complete successfully sent
_The time error (E) is later than ₁₃ . Therefore it is impossible to perform a time setting precise time t ₁₃ (although time error E in this case is small).

The present invention has been made in view of the above points, and an object of the present invention is to provide a time information transmission method which does not cause an error in time alignment even when a transmission failure occurs when transmitting time information in the HDLC method. It is in.

E. Means and Actions for Solving the Problems The present invention provides control from a control station to a controlled station or from a central control station according to a high-level data link control procedure having a function of retransmitting information when a transmission failure occurs. In a time information transmission method for transmitting time information to a controlled place via a station, the receiver monitors the elapsed time from when a time advance signal is input to when a time execution signal is input, and monitors the elapsed time. Is provided with elapsed time determination means for determining whether or not is equal to a set time, wherein the elapsed time is not equal to the set time, when the elapsed time determination means determines, is not treated as time information, I have.

F. Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings. According to the present invention, in the data transmission by the HDLC method, an elapsed time determination means is provided on the receiving side, and the elapsed time determination means performs processing as shown in FIG. Determining first whether the input data is the time the warning signal at step S ₁ in FIG. 1. As a result the input data when a time warning signal starts a timer in step S _2. Also if the input data is not time warning signal in step S _2, it determines whether it is time execution signal. Performs processing as a general data in step S ₄ if the result input data is not time execution signal. When the input data is a time execution signal, the elapsed time from when the timer is started to when it is determined to be the time execution signal (that is, from when the time notice signal is input until the time execution signal is input). of time) or not equal to a predetermined set time T, is determined in step S _5. As a result when the elapsed time is equal to the set time T is handling the input data as the time information, and resets the timer and executes the time adjustment in step S _6. If the elapsed time is not equal to the predetermined set time T,
Not address the input data as the time information, the time alignment is not performed resets the timer in step S _7.

As described above, the elapsed time determination means of the present invention compares input data as time information by comparing the elapsed time from the input of the time notice signal to the input of the time execution signal with the set time T. Specifically, the set time T is set to the above-mentioned time T _{1 in} FIG. 5 (a) (the time interval between the time advance notice signal and the time execution signal when transmitted normally). Should be set equal to.

Next, the transmission method of the present invention including the elapsed time determination means set as described above will be applied to the cases of FIGS. 5 (a) to 5 (f). First, in the case of FIG. 5 (a), the data retransmitted by the retransmission request is the data after +1 and the time information before that is not retransmitted. Moreover, since the time the warning signal the amount of time elapsed since the input to the time execution signal is input is equal to the set time T _1, time setting is performed by the time execution signal transmitted, there is no problem.

Next, when the time execution signal transmitted from the downstream side is lost due to a transmission failure as shown in FIG. 5 (b), the upstream side issues a reject REJ to request a retransmission. Then, the downstream side retransmits the time execution signal and the data of +1 and +2 after the transmission frame (+2) in the same time zone as the reject REJ. The elapsed time T ₂ becomes from this for the time warning signal is input to the time execution signal is input, the set time by T ₁ (step S ₅ of FIG. 1) the elapsed time T ₂ are the elapsed time determining means (T ₁ <T ₂ ). As a result, the re-transmitted time execution signal is not treated as time information, and time adjustment is not performed at an incorrect time. In this case, the time cannot be adjusted, but if the accuracy of the clock is sufficiently increased, the time may be adjusted by the time execution signal transmitted in the next cycle.

In addition, when the time notice signal transmitted from the downstream side is lost due to a transmission failure as shown in FIG. 5 (c), the upstream side issues a reject REJ to request retransmission. Then, the downstream side retransmits the time notice signal, the time execution signal and the data of +1 from the data following +1. Here, since the time the warning signal and the time execution signal for retransmission is simply be retransmitted in order, the time interval T ₃ is different from the set time T _1. Therefore, the elapsed time determination means determines that T ₃ ≠ T ₁ , and the retransmitted time execution signal is not treated as time information, so that time adjustment is not performed at an incorrect time.

Also, as shown in FIG. 5 (d), -1 transmitted from the downstream side
5C, the upstream side issues a reject REJ and issues a retransmission request as in the case of FIG. 5 (c). In response to this, the downstream side receives −1, a time notice signal and a time execution signal. Resend. Since the time the warning signal and the time execution signal to be retransmitted is merely be retransmitted in order, the interval T ₄ that time is different from the set time T _1. For this reason, it is determined by the elapsed time determination means that T _{4 、} T ₁ , and the retransmitted time execution signal is not treated as time information, and time adjustment is not performed at an incorrect time.

In addition, as shown in FIG. 5 (e), when data of -2 two before the time notice signal is lost, the up side is rejected.
A retransmission request is made by issuing a REJ. Then, the downstream side retransmits the data of -2, -1 and the time advance notice signal, and then transmits the time execution signal. Time warning signal and the next time execution signal in this case retransmission simply because only be sent in the order, the interval T ₅ the time is shorter than the set time T _1.
Therefore it by the elapsed time determining means is a T ₅ <T ₁ is determined. Time Run signal input in this order time t ₁₂ is not handled as the time information, never time synchronization at a wrong time from being executed.

In addition, in the case of FIG. 5 (f), the input of the time execution signal is slightly delayed due to the intervention of the reject REJ.
T ₆ is not equal to the set time T ₁ by the elapsed time determining means (T ₁ <T ₆₎ It is determined. As a result, time t ₁₄
Is not treated as time information, and time adjustment is not performed at an incorrect time. If it should be noted the difference between the time T ₁ and T ₆ are very small, although the accuracy of the determination can also be determined that T ₁ = T _6, also the error as was time setting in this case is extremely There is no problem because it is small.

G. Effects of the Invention As described above, according to the present invention, if the elapsed time from when the time notice signal is input to when the time execution signal is input is not equal to the set time, the time is not treated as time information. Therefore, when performing data transmission by HDLC method,
Even if a transmission failure occurs, an excellent effect that no error occurs in time adjustment and time management between the control stations of the remote monitoring control station and between the controlled stations can be obtained. Moreover, the advantage of the HDLC system that data can be retransmitted when a transmission failure occurs does not deteriorate at all.

[Brief description of the drawings]

FIG. 1 is a flowchart showing one embodiment of the present invention, and FIG.
FIG. 3 is an explanatory diagram showing a responsibility sharing level in a transmission system, FIG. 3 is a frame configuration diagram showing a transmission format of the HDLC system, FIG. 4 is a time chart showing a transmission form by the HDLC system when a transmission failure occurs, (A) to (f) are time charts for explaining each frame transmission state.

Claims (1)

(57) [Claims] 1. A method according to a high-level data link control procedure having a function of retransmitting information when a transmission failure occurs, from a control station to a controlled station or from a central control station to a controlled station via a control station. In the time information transmission method for transmitting information, the receiver monitors the elapsed time from when the time notice signal is input to when the time execution signal is input, and determines whether the elapsed time is equal to the set time. A time information transmission method, wherein when the elapsed time determination means determines that the elapsed time is not equal to a set time, the elapsed time determination means does not treat the elapsed time as time information.