JP3417801B2 - Remote monitoring control device and communication method therefor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distant supervisory control system, and more particularly to a communication method for automatically adjusting a communication speed according to a CDT communication method between a master station device and a plurality of slave stations.

[0002]

2. Description of the Related Art In a remote monitoring control system, control information is transmitted from a master station to an upstream slave station valve valve on the basis of information transmitted from the slave station, for example, information from a plurality of slave stations in a water supply and sewerage system. Then, it is automatically controlled. However, when the slave station information changes frequently, or when a large amount of urgent control information continues for a long time, the transmission / reception processing unit of the master station becomes overloaded and data loss occurs. , There were cases where the reliability of the system was impaired.

As a method for solving such a problem,
In Japanese Patent Laid-Open No. 4-86137 and Japanese Patent Laid-Open No. 8-340586, in the 1: N communication control of the master station and the slave station by the polling method, polling is thinned out to the slave station with no response or no data, and the priority is set. Discloses a proposal to change the polling period for a slave station.

[0004]

The polling transmission method according to the above cited example is effective for a remote monitoring control system in which transmission data is relatively slow and the data amount is small. However, no consideration is given to a cyclic transmission method (hereinafter, referred to as CDT: Cyclic Digital Telemeter) that handles high-speed data and has a large amount of data.

In the CDT method, one master station and a plurality of slave stations face each other, and a transmission / reception frame containing a plurality of data is cyclically transmitted to each slave station. In other words, transmission / reception processing is performed in parallel and cyclically between the master station and a plurality of slave stations. When the state change from the previous value occurs in each data in the transmission and reception frame, the reception process in the master station,
Next, reception processing is required in the slave station. However, if a large amount of data is changed, the reception process cannot catch up and traffic is busy, resulting in data loss.

An object of the present invention is to overcome the above-mentioned problems and to provide a highly reliable remote monitoring control device with no reception leakage and a communication method therefor.

[0007]

The above object is to provide a CD in which one master station device and a plurality of slave station devices are connected by a transmission path.
In the distant monitoring control device of the T communication system, the processing load of the transmitting / receiving unit of the master station device is measured, and the communication speed of each slave station is adjusted according to the processing load so that traffic busy (data loss) in the load can be avoided. It is characterized in that it is changed step by step.

The communication speed is changed by optimizing the communication speed of each slave station for each load level obtained by dividing the processing load of the master station device from 0% in the idling state to 100% in which the traffic is busy. It is performed according to the set load-corresponding speed pattern. The pattern is set so that the higher priority of the slave station is changed later.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an example of the configuration of a remote monitoring control system. In this system, the master station device 1 is connected to the computer 3 via the bus 4, and a plurality of slave station devices 2-1 to 2-1 are connected via the public line 5.
2-N is connected to monitor and control the main equipment 8 such as pumps and valves, which are the controlled devices.

The master station device 1 inputs data of an operation start command / operation stop command for the slave station 2 from the monitor control console 6,
It is edited by the monitor control unit 12, converted into a transmission protocol to the slave station device 2 by the transmission / reception unit 13, and sent to the slave station device 2 via the modem 15.

On the other hand, the operating state of the main unit 8 sent from each of the slave stations 2, that is, the operating state of the valve, the start / stop of the pump, the flow rate of the reservoir, and the abnormality in the slave station 2 (program Each data (abnormality, hardware abnormality, etc.) is taken into the transmission / reception unit 13 via each modem 15 and displayed on the graphic panel of the monitoring control console 6 via the monitoring control unit 12. The operator, for example, sees the flow rate under the control of the slave station device 2-N and issues a control command for opening / closing the valve of the slave station device 2-1 located upstream of the flow rate via the monitoring control unit 12. It is given to the transmitting / receiving unit 6. Alternatively, the computer 2 that has acquired the operating state of the main machine device 8 via the host system interface unit 11
The automatic control command is transmitted to the transmitter / receiver 13.

A master station apparatus 1 and a slave station apparatus 2 in this embodiment
The communication is based on the CDT method in which the transmitting / receiving unit 13 transmits and receives cyclically and in real time. In Figure 2,
The conceptual diagram explaining the communication of 1: N type CDT is shown.
In the 1: N CDT system, the transmitter / receiver 13 of the master station 1 receives the slave stations 2-1 to 2-1 through the modems 15-1 to 15-N, respectively.
2-N and opposite channels are provided, and the public line 8 is used for the transmission path of each channel. Therefore, it is possible to collect data in a cyclic manner simultaneously with N slave stations 2. Cyclic transmission between the master station 1 and each slave station 2 is performed by a transmission / reception transmission frame having a synchronization signal and a data portion of words 1 to n. For example, in the transmission frame with the slave station 1, word 1 includes information from the slave station 2-1 indicating the opening / closing state of the valve, and word 2 includes information from the master station 1 indicating the opening / closing control command of the valve. Be done. The number of words may differ for each slave station.

The master station 1 and the slave station 2 check each received word in the transmission frame, and perform a necessary receiving process when the received word is different from the previous value. Therefore, when there is a change in the state of the information received from the slave station 2 and a control command is issued from the computer 3 or the supervisory control console 5, the load on the master station device 1 temporarily increases suddenly. At this time, if data transmission is performed by high-speed communication, the reception process cannot follow the amount of received data accumulated in the reception buffer, traffic busy occurs, and as a result, reception omission occurs.

This embodiment variably controls the communication speed of each channel (CH) according to the load in order to avoid reception leakage when the load is high. For this reason, the transmission / reception unit 13 is provided with a load measurement unit 14, a communication speed change processing unit 16, and a communication speed table 17. The load measuring unit 14 is composed of an OS or a watchdog timer (WDT), constantly measures the throughput of the transmitting / receiving unit 13 registered as one of the application tasks, and acquires the fluctuation of the processing load in real time.

FIG. 3 shows an example of a communication speed setting table between a master station and slave stations. An example of 5CH is shown as the slave station opposite channel parameter, and the SSNo (Sub S
tation No) and communication speed BPS (Bit Per Second) are assigned according to the load rank. The illustrated load rank is 0
20%, 20-40%, 40-60%, 60-8
There are 5 levels of 0% and 80% or more. By the way, in the ranks, high-speed 2400BPS for each CH, in ranks CH1, 3, 5 for 2400BPS, CH2, 4 for 120
0BPS, 200 for each CH at the highest load rank
BPS is set by downline loading from PC7 (personal computer).

The CHs 2 and 4 in this example have a low priority, and the communication speed is lowered earlier than other CHs like rank. This is because the data handled by the opposite station of CH2 and CH4 is less required to have high speed than other CHs.
In a normal system configuration, a slave station that handles high-speed communication data is classified into a slave station and a slave station that does not handle the communication data. Therefore, it is easy to determine the priority order based on the communication characteristics of each slave station. Further, the communication speed of each CH is parameterized and loaded from the PC 7 or the like to allow any change, thereby improving the versatility of the master station device.

FIG. 4 shows a flowchart of the communication speed changing process. The communication speed change processing unit 16 loads data from the PC 7 into the communication speed table 17 as an initial setting (A10). Next, the current value of the processing load is acquired from the load measuring unit 14, a load rate with a traffic busy load amount of 100% is obtained (A20), and the rank to which the load rate corresponds is identified (A30). . Next, the load factor branches according to the applicable rank, and the communication speed setting table 17
And change the communication speed of each CH (A40 to A40).
80).

[0018]

According to the CDT communication method of the present invention, since the communication speed with each slave station is changed stepwise according to the processing load of the master station, the delay of the reception processing due to the data state change in the transmission frame. By avoiding, it is possible to prevent the occurrence of traffic busy.

According to the present invention, the main station connected to the slave station is monitored / monitored from the master station by CDT communication.
In the distant monitoring control device that controls, the processing load of the master station is measured, and the communication speed of the master station and each slave station is reduced according to the speed pattern in which the communication speed of the slave station with the lower priority is reduced first according to the load rank. Since it is variable, it is possible to prevent the reception omission when the processing load is suddenly increased due to the data state change of the main machine device or the control command change, and it is possible to improve the system reliability.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a remote monitoring control system according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram illustrating the configuration and operation of a 1: N type CDT system.

FIG. 3 is an explanatory diagram showing a configuration of a communication speed setting table and an example of setting in units of CH.

FIG. 4 is a flowchart showing communication speed change processing.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Master station device, 2 ... Slave station, 3 ... Computer, 4 ... System bus, 5 ... Public line, 6 ... Monitoring control console, 7 ... PC (personal computer), 8 ... Main machine device, 11 ... Host system interface part,
12 ... Monitoring control unit, 13 ... Transmitting / receiving unit, 14 ... Load measuring unit, 15 ... Modem, 16 ... Communication speed change processing unit, 17 ...
Communication speed setting table.

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kimio Nemoto 3-2-1, Saiwaicho, Hitachi, Ibaraki Prefecture Hitachi Engineering Co., Ltd. (72) Inventor Yo Takahashi 3-18-1 Omikacho, Hitachi, Ibaraki Ibaraki Hitachi Information Service Co., Ltd. (56) Reference JP-A-60-171849 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04Q 9/00

Claims (3)

(57) [Claims] 1. N slave stations and one slave connected to each slave station.
Alternatively, in a communication method of a remote control monitoring system including a master station that receives a state quantity measured from a plurality of master machines and transmits a control command to the master machine, the master station and the N slave stations are opposed to each other. In the case of performing cyclic data transmission, the communication speed of each slave station is set in advance for each of a plurality of load ranks with the load at which the master station generates a traffic busy being set as an upper limit, and the processing of the master station is performed. When changing the communication speed of each slave station to the communication speed of the corresponding load rank according to the measured load in the
Communication method for remote monitor control device baud rate is characterized by Rukoto decrease faster lower slave station priority. 2. N slave stations and 1 connected to each slave station.
Alternatively, in a remote control monitoring system including a master station that receives state quantities measured from a plurality of main machines and transmits a control command to the main machines, a CDT with N channels facing each other between the master station and N slave stations. Set the combination pattern of the communication means and the communication speed of each channel to the upper limit of the traffic busy state of the transmission / reception processing of the master station.
Communication speed setting table set for each of a plurality of load ranks, load measuring means for measuring the load of transmission / reception processing of the master station, and communication speed of each channel by referring to the speed setting table according to the measured load A distant monitoring control device, characterized in that a communication speed changing means for changing the distance is provided. 3. The communication system according to claim 2, wherein each channel of the communication speed setting table is provided with a priority order, and the communication speed is set to be lowered from the channel having the lowest priority order. A distant monitoring control device characterized by assigning to a corresponding channel according to characteristics.