JPH0666188U - Remote monitoring terminal equipment - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a remote monitoring terminal device capable of detecting an abnormal value of an input value of an analog signal due to a failure of a sensor or the like. A comparison unit 5 for comparing an input value of an analog signal from an analog signal line 3 from a sensor 1 to an A / D conversion unit 2 and a maximum input value that can be read by a central processing unit 4.
Is provided with the remote monitoring terminal device 6.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a distant monitoring terminal device that A / D converts an analog output of a sensor that detects a state of a monitored object into a digital value and then transmits the digital value to a central monitoring device.

[0002]

[Prior art]

 Conventionally, for example, as a monitoring device for this type of monitored object, a gas sensor is used to monitor the filling state of gas in a gas cylinder with an analog value larger than "0", and a public telephone line is used. A monitoring system that sends data to a central monitoring device has been put to practical use.

A conventional remote monitoring terminal device includes an A / D conversion unit 21 for converting an input value of an analog signal from a sensor for measuring a state of a monitoring target into a digital signal as shown in FIG. 4, and an A / D conversion. A communication interface unit 22 for transmitting the generated digital signal to a central monitoring device via a public telephone network, a memory unit 23 for storing information such as data and commands, and a central processing unit 24 for controlling the operation of the entire device. The central processing unit 24 was able to read the input value of the analog signal in the range of 4 to 20 mA and 1 to 5V.

On the other hand, in the remote monitoring and control system, in order to reduce the load on the central monitoring device, analog limit value data is given to the terminal device, a threshold is applied by the analog value to detect an abnormality, and the terminal device is detected. Japanese Patent Laid-Open No. 63-208393 proposes a method of sending an alarm to a central monitoring device. Here, only the means for detecting an abnormality in the terminal device is shown by using the analog value as it is.

[0005]

[Problems to be solved by the device]

 However, according to the above-mentioned conventional telemeter terminal device, since there is no analog signal line disconnection judgment circuit, the analog input data value is stored as "0", and the data value or the alarm value which is urgently required is kept correct in the normal operation. However, there was a drawback in that it could not be sent to the central monitoring device. In the remote monitoring terminal equipment shown in FIG. 4, if an abnormal value (21 mA or more or 5.1 V or more) in the input value of the analog signal occurs due to a failure of the sensor, etc., the central monitoring device performs A / D conversion. The data to be transmitted is FFH in the case of 8-bit A / D conversion and is the same as the data when the maximum input value is 20 mA or 5 V, so the central monitoring unit cannot detect the abnormal value and If left unattended for a certain period of time, there was a defect that the terminal device was destroyed due to overvoltage.

Therefore, the present invention is to provide a remote monitoring terminal device capable of detecting an abnormal value of an input value of an analog signal due to a failure of a sensor or the like.

[0007]

[Means for Solving the Problems]

 In order to solve the above-mentioned problem, a comparator is provided for comparing the input value of the analog signal from the analog signal line from the sensor to the A / D converter and the maximum input value that can be read by the central processing unit. Is.

[0008]

[Action]

 After the analog signal from the sensor is converted from analog signal to digital signal by the A / D converter, the data value of the digital signal is read by the central processing unit, and the converted data value can be read by the central processing unit ( If the maximum input value FFH is 4 to 20 mA, 1 to 5 V), the comparison unit compares it with the input value of the analog signal before conversion, and the input value of the analog signal exceeds the maximum input value (20 mA or 5 V). If so, it sends an abnormal value to the central monitoring unit. If it is less than the maximum input value, the converted data is stored in the memory unit.

[0009]

【Example】

 An embodiment of a remote monitoring terminal device according to the present invention will be described with reference to the accompanying drawings.

FIG. 1 is an explanatory diagram of a configuration of a remote monitoring terminal device apparatus according to the present invention, FIG. 2 is an explanatory diagram of a block diagram of a remote monitoring terminal according to the present invention, and FIG. 3 is a remote monitoring terminal of FIGS. 1 and 2. It is an explanatory view of a flow chart of the device, and compares the input value of the analog signal from the analog signal line 3 from the sensor 1 to the A / D conversion unit 2 with the maximum input value that can be read by the central processing unit 4. The remote monitoring terminal device 6 provided with the comparison unit 5 is provided.

After the analog signal from the sensor 1 is converted from an analog signal to a digital signal by the A / D conversion unit 2, the central processing unit 4 reads the data value of the digital signal, and in the case of 8-bit conversion, after conversion If the data value is the maximum input value FFH within the range (4 to 20 mA, 1 to 5 V) that can be read by the central processing unit 4, the comparison unit 5 is driven to compare with the input value of the analog signal before conversion. When the input value of the analog signal exceeds the maximum input value (20 mA or 5 V), the error command is read from the memory unit 7 and the abnormal value is transmitted to the central monitoring unit 9 by the communication interface unit 8. When the input value is less than the maximum input value, the converted data is stored in the memory unit 7.

[0012]

[Effect of device]

 As described above, in the remote monitoring terminal device according to the present invention, the input value of the analog signal from the analog signal line from the sensor to the A / D conversion unit and the maximum input value that can be read by the central processing unit are set. Since a comparison unit for comparison is provided, an abnormal value of the input value of the analog signal due to a malfunction of the sensor, etc. is detected, the abnormal value is transmitted to the central monitoring device, and the processing for the abnormal time is promptly performed. In addition to the above, the remote monitoring terminal device has an excellent effect such that the reliability of the device can be improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a configuration of a remote monitoring terminal device apparatus according to the present invention.

FIG. 2 is an explanatory diagram of a block diagram of a remote monitoring terminal device according to the present invention.

FIG. 3 is an explanatory diagram of a flowchart of the remote monitoring terminal device of FIGS. 1 and 2.

FIG. 4 is an explanatory diagram of a block diagram of a conventional remote monitoring terminal device.

[Explanation of symbols]

1 ... Sensor, 2 ... A / D converter, 3 ... Analog signal line, 4 ... Central processing unit, 5 ... Comparison unit, 6
... Remote monitoring terminal equipment, 7 ... Memory unit, 8 ...
Communication interface unit, 9 ... Central monitoring device.

Claims (1)

[Scope of utility model registration request] 1. An A / D for converting an input value of an analog signal from a sensor for measuring a state of a monitored object into a digital signal.
A conversion unit, a communication interface unit for transmitting the A / D converted digital signal to a central monitoring device via a public telephone line network, a memory unit for storing information such as data and commands, and operation of the entire device In a remote monitoring terminal device having a central processing unit for controlling the above, an input value of the analog signal from an analog signal line from the sensor to the A / D conversion unit and a maximum input value that can be read by the central processing unit are set. A remote monitoring terminal device comprising a comparing unit for comparing.