JP2850637B2 - Time synchronization device for supervisory control system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a supervisory control system comprising a main control unit and a plurality of sub-control units, and more particularly to a device for synchronizing the time of an internal clock of each control unit.

[0002]

2. Description of the Related Art Generally, in a supervisory control system such as an EIC integrated system in which electric control for controlling electric power and power relations, various types of instrumentation control, and computer control for performing prediction operation and optimization operation are integrated, a plurality of systems are used. Although a configuration in which a workstation or the like is connected is adopted, in such a system, it is necessary to synchronize the time of an internal clock of a workstation such as an operator station.

FIGS. 4 and 5 show an outline of a conventional time synchronization system in this type of system. In the figure, 1-1,1
-2 is an operator station. Each of the operator stations 1-1 and 1-2 includes a CRT 2 and a CPU 3 for controlling the CRT 2 and the like. Each of the CPUs 3 has an internal clock 4. On the other hand, the host CPU of the host device 5
6 also has an internal clock 7. 8 is an external clock. Conventionally, for example, as shown in FIG.
The time synchronization is performed by reading time data from the external clock 8 at a constant period by the clocks 3 and 6, respectively. In the case of this method, although highly accurate time synchronization can be performed, there are disadvantages in that the system configuration is complicated and the cost is hindered.

In view of this, as shown in FIG. 5, a time management process for taking in time data from the external clock 8 is incorporated only in the host CPU 6, and the other CPUs 3
3 is provided with a method of transmitting time data from the host CPU 6 at a constant cycle.

[0005]

However, in the time synchronization system shown in FIG. 5, the internal clock 7 is initialized when the host CPU 6 starts up, and there is a possibility that the control operation may be inconvenient. If a device having a backup function is used as the internal clock 7 of the host device 5, this problem can be solved. However, in this case, there is a problem that the host device 5 becomes expensive.

The present invention has been made in view of the above-mentioned problems, and in a time synchronization technique of a monitoring control system including a main control unit and a plurality of sub-control units, it is possible to simplify and reduce the cost of the system while securing predetermined time synchronization accuracy. The purpose is to aim.

[0007]

FIG. 1 shows the configuration of the present invention. In order to achieve the above object, the present invention is directed to a monitoring control system including a main control unit 9 having an internal clock and a plurality of sub-control units 10, and a timepiece management system for performing time management of each control unit. The time synchronization device employs the following means.

(1) The main control unit 9 includes the following elements.

A) At the time of start-up, it is selected with priority over other application process means, acquires the initial time 11-1 from the sub-control unit 10, and sets the initial time 11-1 in the internal clock 12 of the unit. Initial time setting means 13 to be set.

B) Corrected time transmitting means 1 which is periodically selected, acquires time 11-2 from internal clock 12 of the unit, and transmits it to each sub-control unit 10 as a corrected time.
4.

(2) Each sub-control unit 10 has the following elements.

A) When the correction time 11-2 is received, it is selected, and the correction time 11-2 and the internal clock 15 of the unit are selected.
Time difference determining means 16 for comparing with the time 11-3 to determine whether the time difference is within the allowable range.

B) Correction time 11-2 and internal time 11-3
Time correction means 17 which is selected when the time difference between the unit and the unit is within the allowable range, and sets the correction time 11-2 in the internal clock 15 of the unit.

[0014]

According to the present invention, when the main control unit 9 is started, the initial time 11-1 is acquired from the internal clock 15 of the sub control unit 10 which maintains the timekeeping operation, and the internal time of the main control unit 9 is obtained. The clock 12 is set so that a device having no backup function can be used as the internal clock 12 of the main control unit 9. At this time, the time required for obtaining the time can be shortened by giving priority to the internal clock initial setting process over other application processes, and the accuracy of the initial time is ensured.

In a normal state, the main control unit 9 transmits the time 11-2 of the internal clock 12 to each sub-control unit 10 to synchronize the time between the units. At this time, since there is a possibility that a large error due to data transmission may occur at the received correction time 11-2, the sub-control unit 10 sets the correction time 11 based on the internal time 11-3.
After confirming the validity of -2, it is taken into the internal clock 15.

[0016]

Embodiments of the present invention will be described below. FIG. 2 shows an outline of a system configuration of a time synchronization system according to an embodiment of the present invention. In the drawings, the same or corresponding parts as those in the related art are denoted by the same reference numerals, and description thereof is omitted. In this embodiment, a microcomputer is used as the host device 5, and a device having no backup function is used as the internal clock 7. Basically, an external clock 8
(See FIGS. 4 and 5) can be omitted.

FIG. 3 shows a time synchronization procedure in this system. As shown in the figure, in the time management process on the host device 5 side, since the internal clock 7 is not backed up,
Initialize the time at startup. In this initial time setting,
For example, an initial time is obtained from the operator station 1-1. That is, first, a time transmission request is transmitted from the host device 5 to the operator station 1-1.
In response to this request, the operator station 1-1 reads the time data from the internal clock 4 and transmits it to the host device 5. The host device 5 stores the time data in the internal clock 7.
Set to.

At this time, the communication between the host device 5 and the operator station 1-1 is mediated by a link process, but the link process is operated not only by a time management process but also by a request from each application process. . For this reason, when the communication load is high, it takes time until the time data is acquired by the time management process of the host device 5 after the time data is transmitted on the operator station 1-1 side, and the reliability of the time data is reduced. Will drop. Therefore, in this embodiment, when the host device 5 starts up, the time management process is started immediately after the link process is started as the order in which the application processes are started. As a result, the initial time setting can be completed while the load of the link process is still relatively low. As a result, a sufficiently accurate time can be set.

Thereafter, in a time management process in a normal state,
For example, it is assumed that time synchronization is performed once per hour. In this time synchronization, time data is read from the internal clock 7 of the host device 5 and transmitted to each station. Since it is expected that the load on the CPU will increase in each process at every hour, this time synchronization is performed at, for example, n: 30.

When each station receives the time data transmitted from the host device 5, the time management process performs a time correction process. In this process, first, the received time is compared with the internal time on the station side, and it is calculated whether an error between both times is within a preset allowable range. As a result, if the error between the two times is within the allowable range, the received time is set in the internal clock 4, and if the error between the two times exceeds the allowable range, the time is not set. As a result, when the link process is in a high load state and the received time has a large error as described above, the time need not be taken.

[0021]

As described above, according to the present invention,
When the main control unit starts up, the initial time can be set by accurately capturing time data from the sub control unit. Therefore, no external clock device is required, the system configuration is simplified, and the cost of the system is improved. Also, in the time management process in the sub control unit, highly reliable time data can be taken from the main control unit, so that it is not necessary to separately take time from an external clock, and the structure of the process is simplified.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of the present invention.

FIG. 2 is a block diagram showing a time synchronization method according to one embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a time synchronization procedure according to the embodiment of FIG. 2;

FIG. 4 is a block diagram showing a conventional time synchronization method.

FIG. 5 is a block diagram showing a conventional time synchronization method.

[Explanation of symbols]

 9 Main control unit 10 Sub-control unit 11-1 Initial time 11-2 Modified time 11-3 Internal time 12 Internal clock 13 Initial time setting means 14 Corrected time transmitting means 15 Internal clock 16 Time difference determination means 17: Time correction means

Claims (1)

(57) [Claims] An apparatus for monitoring and controlling a main control unit having an internal clock and a plurality of sub-control units and performing time management of each control unit. Initial time setting means for obtaining an initial time from the sub-control unit, which is selected prior to the application process means, and setting the initial time in the internal clock of the unit; And a correction time transmitting means for transmitting the correction time to each sub-control unit as a correction time, wherein each of the sub-control units is selected when the correction time is received, and outputs the correction time and the time of the internal clock of the unit. A time difference determining means for comparing to determine whether the time difference is within an allowable range; and Time synchronization device of the monitoring control system is characterized in that a time correction means for setting a correction time in the internal clock of the selected the unit Rutoki.