JP2000134680A - Communication system for installation operation monitoring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the reliability of data transmission to data defects such as noise without increasing communication loads by performing recovery with a polling type communication system in the case the transmission data by a broadcast communication system become defective. SOLUTION: When installation operation state signals inputted to a digital input unit 5 are changed, installation operation state data 152 are immediately transmitted to plural state display units 101-103. Further, after the lapse of a retransmission interval t3 set beforehand, the installation operation state data 153 are retransmitted in case the equipment operation state data 152 are not accurately transmitted. The operation is repeated corresponding to the number of times of retransmission set beforehand. Further, in case the retransmitted equipment operation state data 152-154 are not accurately transmitted, data request messages 136-138 are transmitted corresponding to a polling cycle t1 set beforehand and the response data 155-157 are received. Thus, a communication channel abnormality detection function provided in the polling type communication system is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication system of an equipment operation monitoring device, and more particularly to a communication method of a broadcast communication system which is executed when the state of an equipment operation state signal is changed, which indicates the operation state of the equipment. The present invention relates to a communication system which performs recovery by a polling type communication system and adds a repeat function to a broadcast communication system to improve reliability of data transmission.

[0002]

2. Description of the Related Art In general, an equipment operation monitoring device is provided with an analog signal for periodically monitoring data transition from a large number of equipments installed in a wide range, and an equipment operation status signal indicating the operation status of the equipment. And collects and displays data. Further, an alarm signal indicating an abnormality of the equipment may be used to perform an alarm process such as displaying on a display unit or sounding a buzzer at a place different from the data collection device.

In recent years, communication has been used as a means for transmitting these signals because of low wiring cost and long-distance transmission. However, when performing data transmission by communication, the amount of data transmission within a certain period of time is determined by the communication speed. Therefore, in accordance with a signal requiring urgency such as the alarm signal, all data is transmitted by a polling communication method. The data collection method could not cope with the increase in data volume.

For this reason, the analog signal is collected by using a polling type communication system, and the equipment operation state signal and the alarm signal, which are less likely to cause a state change, are devised by using an event driven communication system. Was done.

As for the equipment operation state signal, data is often transmitted to a plurality of displays provided at various places. In such a case, it is necessary to use a broadcast communication system in order to reduce the communication load. was there.

However, in the broadcast communication system,
For example, when transmission data is lost due to noise or the like, there is a problem in reliability of data transmission because it is impossible to confirm whether or not the other device has received the transmission data.

[0007]

The broadcast communication system is an effective means for transmitting the equipment operation state signal having a low frequency of state change to a plurality of devices without increasing the communication load. However, when the broadcast communication method is used, there is a problem in reliability of data transmission as described above.

An object of the present invention is to transmit the equipment operation state signal, which has a low frequency of state change, to a plurality of devices.
An object of the present invention is to improve the reliability of data transmission with respect to data loss such as noise without increasing the communication load.

[0009]

In order to achieve the above object, two types of communication protocols of a polling type communication system and a broadcast communication system are incorporated, and two protocols are used together for one data; This is to incorporate a program that adds a repeat function to the broadcast communication method.

That is, when the state of the equipment operation state signal changes, data transmission is immediately performed by the broadcast communication method. If the communication line quality is poor due to the influence of noise or the like, data is retransmitted by adding a repeat function. Further, data collection is performed using the polling communication method in preparation for loss of transmission data in the broadcast communication method. At this time, a longer polling cycle is better in order not to increase the communication load.

[0011] Thus, double recovery can be performed for data loss in the broadcast communication system while suppressing the communication load, and the reliability of data transmission can be improved.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a communication system according to the present invention will be described in detail with reference to embodiments shown in FIGS. 1, 2, 3, 4, and 5. FIG.

FIG. 1 is an overall configuration diagram of a facility operation monitoring device, FIG. 2 is a timing chart of a polling communication system, FIG. 3 is a timing chart of an event driven communication system, and FIG.
FIG. 5 is a timing chart of the broadcast communication method, and FIG. 5 is a timing chart when the polling communication method and the broadcast communication method (with a repeat function) are used together.

In FIG. 1, reference numeral 1 denotes a sensor for measuring temperature, pressure, flow rate and the like. Reference numeral 2 denotes an equipment operation state signal indicating the operation state of the equipment. Reference numeral 3 denotes an alarm signal indicating an abnormality of the equipment. Reference numeral 4 denotes an analog input unit that receives an analog output of the sensor 1 and outputs the value through communication. Reference numeral 5 denotes a digital input unit which receives an operation state signal as input, and outputs the value through communication. Reference numeral 6 denotes an alarm unit which receives the alarm signal 3 and outputs the value through communication. 8
Is a data collection unit having a data storage function and a display function. Reference numeral 9 denotes an alarm output unit provided with an alarm display function and an alarm indicator (such as a buzzer). Reference numeral 10 denotes a state display unit for displaying the equipment operation state. 7
Are analog input unit 4 and digital input unit 5
The communication line connects the alarm unit 6, the data collection unit 8, the alarm output unit 9, and the display 10.

The data collection unit 8 shown in FIG. 1 collects data from the analog input unit 4 using a polling type communication system. The communication timing between the data collection unit 8 and the analog input unit 4 will be described with reference to FIG.

FIG. 2 is a timing chart of the polling communication method. When collecting data from a plurality of analog input units, first, a data request message 131 is transmitted from the data collection unit 1 to the analog input unit 41. Upon receiving the data request message 131, the analog input unit 41
Returns 1. The data collection unit 8 that has received the response data 141 sets a data processing time t for the response data 141.
After a lapse of two, a data request message 132 is transmitted to the next analog input unit. This operation is repeated for the number of analog input units to be collected.

In this embodiment, the case where the communication is completed normally is described. However, when the data collection unit 8 cannot receive the response data 141 to 145 due to a communication error or the like (timeout), the data request message 131 is issued.
When the response data 141 to 145 are not received despite the retransmission processing,
Of course, it is possible to detect a communication line abnormality.

Therefore, in the polling type communication method, the allowable minimum polling cycle is determined by the number of data to be collected. Since the polling cycle t1 becomes the data update cycle as it is, it is desirable to make it as short as possible.
For this reason, the equipment operation state signal and the alarm signal, which have a low frequency of signal change, are not collected by the polling communication method.

The alarm signal detected by the alarm unit 5 in FIG. 1 is transmitted to the alarm output unit 9 using an event-driven communication system, and the alarm output unit performs alarm display and buzzer output. The communication timing between the alarm unit 5 and the alarm output unit 9 will be described with reference to FIG.

FIG. 3 is a timing chart of the event-driven communication system. Generally, the frequency of occurrence of alarms is low, and it is not preferable to collect alarm signals by a polling communication method from the viewpoint of a polling cycle and a communication load. Therefore, when an alarm signal changes (when an alarm is detected)
Uses an event-driven communication method that transmits data only.

In FIG. 3, when an alarm signal is changed in the alarm unit 9, the alarm unit 61 immediately sends alarm data 146 to the alarm output unit 9. The alarm output unit returns a normal response when the alarm data is normally received. When the warning unit 61 receives the normal response, the transmission sequence of the warning signal is completed. Therefore, the occupation time of the communication line is 116 to 118 in FIG. 3, and the communication load is applied only when the alarm signal changes. However, in a system in which a change in the alarm signal occurs frequently, it is difficult to predict the communication load, so care must be taken.

The equipment operation status signal 2 input to the digital input unit 5 of FIG. 1 is transmitted to a plurality of status display units 10 using a broadcast communication method, and displays the operation status of the equipment. The communication timing between the digital input unit 5 and the status display unit 10 will be described with reference to FIGS.

FIG. 4 is a timing chart of a general broadcast communication system. FIG. 5 is a timing chart in the case where a repeat function is added to the broadcast communication system and further used in combination with the polling communication system.

Referring to FIG. 4, a digital input unit 51
When the equipment operation state signal input to the device changes, the equipment operation state data 149 is immediately transmitted to the plurality of state display units. Since there is no response frame in the broadcast communication method, the transmission sequence is completed when the transmission of the equipment operation state data ends. Therefore, the communication line occupation time 119 to 121 can be shorter than other communication systems, and the effect is particularly high as the number of status display units is large.

However, since there is no response frame, it cannot be determined whether the equipment operation status signal has reached the status display unit without fail, and there has been a problem in the reliability of data transmission. To compensate for this, a repeat function was added to the broadcast communication system as shown in FIG. 5, and the reliability of data transmission was improved by using the polling communication system together.

In FIG. 5, when the equipment operation state signal input to the digital input unit 5 changes, the equipment operation state data 152 is displayed on a plurality of state display units 101 to 10.
3 immediately. Furthermore, equipment operation state data 1
52, the equipment operation state data 1 after the elapse of the preset retransmission interval t3.
53 is resent. This operation is repeated according to a preset number of retransmissions.

Further, the re-transmitted equipment operation state data 1
In case 52-154 were not transmitted correctly,
Data request messages 136 to 138 are transmitted in accordance with a preset polling cycle t1,
The response data 155 to 157 are received. In addition, this makes it possible to use the communication line abnormality detection function of the polling type communication system as described above.

[0028]

As described above, according to the present invention, it is possible to reduce the data transmission time after a change in the equipment operation state signal while minimizing the communication load without providing special hardware. Defects can be recovered twice. That is, it is possible to improve the speed and reliability of data transmission, which is useful in industrial measurement.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a facility operation monitoring device according to the present invention.

FIG. 2 is a timing chart of a general polling type communication system.

FIG. 3 is a timing chart of a general event-driven communication system.

FIG. 4 is a timing chart of a general broadcast communication system.

FIG. 5 is a timing chart when the polling communication method and the broadcast communication method (with a repeat function) according to the present invention are used together.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Measurement sensor, 2 ... Equipment operation state signal, 3 ... Alarm signal, 4,41,42,43 ... Analog input unit
5, 51, 52, 53 ... digital input unit, 6, 6
1, 62, 63: alarm unit, 7: communication line, 8: data collection unit, 9: alarm output unit, 10, 10
1, 102, 103 ... status display unit, 11, 11
1,112,113,114,115,116,11
7, 118, 119, 120, 121, 122, 12
3, 124, 125, 126, 127 ... communication line occupation time, 131, 132, 133, 134, 135, 13
6,137,138... Data request message, 141,
142,143,144,145,146,147,1
48,149,150,151,152,153,15
4,155,156,157 ... data, 160,16
1,162: Communication response message, t1: Polling cycle, t2: Received data processing time, t3: Retransmission interval.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinzo Noguchi 500 Utsuhara-cho, Uchihara-cho, Higashiibaraki-gun, Ibaraki Prefecture Within Hitachi Naka Electronics Co., Ltd. 500 characters of hot water translation mountain Hitachi Naka Electronics Co., Ltd. (72) Inventor Takanori Ito 500 hot water translation mountain of Uchiharacho, Higashiibaraki-gun, Ibaraki Prefecture 500 terms of Hitachi Naka Electronics Co., Ltd. F term (reference) 5K048 AA06 BA21 CA03 EB08 EB10 EB13 FA10 FB04 FB05 FB11 GA03 GB05

Claims (2)

[Claims] An analog input unit having a function of receiving a sensor output signal for measuring a temperature, a flow rate, a pressure, and the like and converting the sensor output signal into a communication output; A digital input unit for conversion, an alarm unit for detecting an alarm from measurement data and an abnormal signal of equipment and outputting the communication, and a function for receiving and communicating information from the analog input unit and the digital input unit and storing and displaying the information. A data collection unit having: a plurality of equipment operation state display units that receive a communication signal of the digital input unit and display equipment operation status; and an alarm that receives a communication signal of the alarm unit and displays an alarm or outputs a buzzer. In the equipment operation monitoring device consisting of output units, the equipment operation status signal with less frequent signal change In addition, the polling communication system that collects data periodically and the broadcast communication system that broadcasts simultaneously without having a communication response function to multiple devices only when there is a signal change are used, and broadcast communication is performed due to disturbance such as noise. A communication method of a facility operation monitoring device, characterized in that even if transmission data by the method is lost, recovery is performed by a polling type communication method. 2. The equipment operation monitoring device according to claim 1, wherein a retransmission function is added to the broadcast communication system so that the number of retransmissions and the retransmission interval can be easily set from outside. Communication method.