JPH1139265A - Method for processing time synchronization - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for processing time synchronization by which the occurrence of errors at the level of milliseconds in a slave device can be eliminated even when time synchronization is made by using time data of the level of seconds. SOLUTION: At the time of executing time synchronization processing, an FEP(front-end processor) reads the time of its built-in clock (S1) and, when the milliseconds of the built-in clock deviates from a tolerance, enters a waiting process until the next correct second comes (S2 and S3). When the correct second comes when the tolerance is met at the next time reading time, the FEP makes time correction by incrementing the seconds of the time by one second (S4 and S5), sets time data (S6), and transmits a time correcting requests to a slave device (S7).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a time synchronization processing method in a remote monitoring control system, and more particularly to a time synchronization processing method between a front end processor and a slave station device.

[0002]

2. Description of the Related Art In a remote monitoring and control system, field devices on the slave station side are monitored and controlled by transmitting monitoring information and control information between a host system and a plurality of slave stations, which are master stations and host computers connected to a network. . In this monitoring control, if there is a time difference between the internal clocks of the higher-level apparatus and the slave station, the state change occurrence time and the control time will be different. Therefore, time synchronization processing between the apparatuses in the system is performed.

In this time synchronization process, the internal clock of the higher-level device is set to the standard time, clock information is transmitted from the higher-level device to each slave station by simultaneous broadcast or polling, and each slave station is transmitted. Side adjusts the internal clock as needed.

Here, as shown in FIG. 3, the slave station performs time synchronization A from the higher-level device to the front-end processor (FEP) 1, and the FEP 1 automatically executes the time synchronization at the timing of the time synchronization request. Synchronize the time of the device, and then
Time synchronization B is performed on the slave station device 2 using the internal clock of EP1. The time data sent from the FEP 1 to the slave station device 2 is
"Day, hour, minute, second".

[0005]

In the conventional remote monitoring control system, the time of the state change occurrence history is stored in units of 10 milliseconds, so that time management in the slave station device is very important. The time data used in the conventional time synchronization processing is performed using "day, hour, minute, second". Time is corrected by setting the following data as “0”.

As described above, since the time data from the FEP 1 to the slave station device 2 is only up to “second”, an error occurs in the time below “second” unless the FEP 1 consciously measures the timing of time synchronization. Let me do it.

For example, as shown in FIG. 4, the internal clock of FEP1 is "xx day, 15:00, 40 minutes, 24 seconds'000".
Time synchronization, and then the time "xx day, 15:00, 4
When the time is synchronized with the slave station device 2 at 0 minutes and 24 seconds '350', the slave station device sets the time “xx”, 15:00, 40 minutes, 24 seconds at “0” after “second”. '000'. At this time, in the slave station device 2, an error of "350 milliseconds" occurs.

It is an object of the present invention to provide a time synchronization processing method which eliminates the occurrence of an error in the "millisecond" range in the slave station even in time synchronization using time data in "second" units.

[0009]

According to the present invention, in the time synchronization process from the FEP to the slave station device, the FEP performs a wait process performed at a timing within a permissible error range from the second of the internal clock of the FEP. In the case where is advanced, "seconds" is incremented by 1 so that the time synchronization processing can always be performed within a permissible error range from the correct second, and is characterized by the following method.

[0010] Time data is transmitted from a higher-level device of the remote monitoring control system to a front-end processor on the slave station side, and the front-end processor performs time synchronization processing of its internal clock and transmits the time data to the slave station device. In the time synchronization processing method of performing time synchronization processing of the slave station device by giving time data in units of seconds, the front-end processor may be configured such that the millisecond of its internal clock is within a permissible error range from a second which becomes zero. Wait processing is performed until a certain timing, and when the permissible error is ahead of the second, the time synchronization processing for the slave station device is performed by adding +1 to the "second" of the time data.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a time synchronization processing procedure from an FEP to a slave station according to an embodiment of the present invention.

When executing the time synchronization process, the FEP 1 reads the time of the internal clock (S1) and refers to the "millisecond" of the internal clock, and the "millisecond" is within an allowable range (for example, ± 50 milliseconds). ) Is checked (S2). When the value is out of the allowable range, the wait process is started until the next right second (millisecond is 0) (S3).

When the next time reading by the wait processing falls within the allowable range, it is checked whether or not this error advances with respect to the second (S4). The time is corrected (S5), and time data is set (S6). In the case of a delay, the time data is set without correcting the time (S6). Thereafter, a time correction request is transmitted to the slave station device together with the time data (S7).

FIG. 2 shows an example of time synchronization according to this embodiment. As shown in (a) of FIG.
Attempts to execute the time synchronization process at "hour, 40 minutes, 24 seconds'350", but since the current time is out of the allowable range with respect to the second, the next time of the second "xx day, 15:00, 40" Min, 25
Wait for the second '000' in the wait process, and correct the internal clock of the slave station device at the second of the second.

As shown in FIG. 2B, when the error with respect to the second is advanced within the allowable error range, the time obtained by adding "second" of the time data to the time "xx day, 15:00, 40 Minutes,
21 seconds '000', and if the error is late, the time "×
× Day, 15:00, 40 minutes, 21 seconds '000'
The time of the slave station device is adjusted.

[0016]

As described above, according to the present invention, the FEP
Performs a wait process performed at a timing within the allowable error range from the second of the internal clock, and further increases the "second" when the error advances, so that time synchronization using time data in "second" units This also has the effect of eliminating the occurrence of an error in the "millisecond" range in the slave station device, and enabling the time synchronization process to always be within the allowable error range from the second.

[Brief description of the drawings]

FIG. 1 shows a synchronization processing procedure according to an embodiment of the present invention.

FIG. 2 is a time synchronization time chart in the embodiment.

FIG. 3 is a time synchronization processing method on the slave station side of the remote monitoring control system.

FIG. 4 shows a conventional time synchronization processing method.

[Explanation of symbols]

 1. Front end processor (FEP) 2. Slave station device

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Fumio Ito 2-1-17 Osaki, Shinagawa-ku, Tokyo Inside Meidensha Co., Ltd.

Claims (1)

[Claims] A time data is transmitted from a higher-level device of a remote monitoring and control system to a front-end processor on a slave station side, and the front-end processor performs time synchronization processing of its internal clock and a slave station device. In the time synchronization processing method of performing time synchronization processing of a slave station device by giving time data in units of seconds to the front end processor, the front-end processor has an allowable error range from a second in which the millisecond of its internal clock becomes 0. Time synchronization until the timing becomes within, and when the permissible error is ahead of the second, the time synchronization is performed on the slave station device by incrementing the "second" of the time data by one. Processing method.