Classification of remote water meters and meter reading systems
When it comes to remote water meters and meter reading systems, many people have a simple impression.But let's talk about the classification and characteristics of remote water meters and meter reading systems, which may not be very clear.
This time, we will talk about how to subdivide the remote water meter and the meter reading system in detail, what are the characteristics of each of them, and give a deep analysis of them.
The remote water meter is based on an ordinary mechanical hot and cold water meter, a passive switch direct-reading remote water meter, and a remote transmission output system.
The meter reading system is established on the basis of the remote water meter. The system integrates the consumption of thousands of households with the computer network center of the management department. The system has a variety of communication methods, flexible networking methods, and convenient expansion. Meet the various needs of users from different angles, and truly realize the scientific management of residential quarters.
Remote water meters and meter reading systems can be divided into two categories; one is electromechanical conversion mode, and the other is transmission mode.
Let's interpret them in turn.
Electromechanical conversion method
At present, the development trend of water meters is already clear, that is, toward the direction of intelligence. Compared with electromechanical water meters, one of the main functions of smart water meters is that smart water meters can more fully apply data.
1. Pulse sampling
Pulse sampling includes the following three sensing methods:
Hall element sensing: A magnet is installed under a certain carry gear, and a Hall element is placed near the circumferential position formed by the rotation of the magnet. When the gear rotates, when the magnet is close to the Hall element, the Hall effect is used to make the Hall element produce a Switching quantity, thus forming a switching pulse signal, the chip determines the water consumption by measuring the pulse signal.
Reed switch sensing: Install a magnet under a certain carry gear, and place a reed switch near the circumferential position formed by the rotation of the magnet. When the gear rotates, when the magnet is close to the reed switch, the reed switch will attract and stay away from the reed switch. When the tube is in charge, the reed switch is disconnected to form a switching pulse signal, and the chip determines the water consumption by measuring the pulse signal.
Non-magnetic sensing: Load sampling pointer on the water meter measurement component structure as sampling signal trigger. The sampling signal trigger is a flat or cylindrical structure with a metal sheet on the surface. The electromagnetic wave scanning signal sent by the reflected sampling circuit is received, and the trigger is When the metal piece enters or leaves the detection scanning area, a complete measurement signal is generated, which is processed by the circuit and output as a digital wave without any resistance to the water meter.
2. Bus system
The bus system is a pair of lines with multiple devices, and the devices have address codes to identify them! The so-called bus (Bus) generally refers to a group of transmission lines that transmit information to one or more destination components with one or more source components through time-sharing multiplexing. It is a public channel for data transmission in the computer!
Photoelectric direct-reading technology: The direct-reading meters currently on the market are divided into two categories by adopting information, namely, through-beam direct-reading meters and reflective direct-reading meters.
Through-beam type: there are light holes on the through-beam type wheel. A light-emitting tube is installed on one side of the type wheel, and a photosensitive tube is installed on the other side. The light emitted by the luminous tube is irradiated to the photosensitive tube through the light hole, and the photosensitive tube performs photoelectric conversion to obtain the corresponding signal potential. The number of light-passing holes and each group of light pipes is designed after strict calculation. Rotate the character wheel, and at each position of reading 0-9, the position and number of light-sensitive pipes for obtaining light are different, and thus the encoding is carried out.
Reflective type: The working principle of the reflective direct reading meter is the same. The difference is that no light hole is made on the character wheel, but a reflective barcode is printed on the outer ring of the character wheel. The light emitted by the luminous tube is not directly irradiated to the photosensitive tube. It is reflected to the photosensitive tube by reflecting the bar code.
It should be noted that, in today's technical environment, the direct reading technology is the mainstream technology, and the reflective direct reading technology has been eliminated.
Camera type: A lens is installed on the reading window of the water meter, and the reading of the meter is photographed for transmission during meter reading.
Transmission method
According to the transmission mode of the water meter, it is divided into three categories: wired transmission and wireless transmission, and IC card meter:
1. Wired transmission
Separate line system: each meter connected to the system does not have a separate address code, and a separate signal line needs to be led to the meter reading device
Bus system: The bus system is divided into RS485 transmission and MBUS transmission.
RS485 is a bus communication standard. It specifies the waveform or electrical signal of each digital data on the transmission line, which belongs to the physical layer. And Mbus stipulates that to transmit a specific function instruction, which numbers need to be transmitted to represent this instruction, which belongs to the communication protocol layer. Just like in Morse code, it is expressed by a short press. It is expressed by a long press-it is the physical layer, and the meaning of the different combinations of dots and strokes is the protocol layer.
2. Wireless transmission
Wireless transmission is divided into short-distance wireless transmission LoRa and long-distance wireless transmission NB-IoT
LoRa is more suitable for local area network, manage data by oneself, set up base station by oneself for data processing, such as a farm, a vegetable base, etc.
NB-IoT is more suitable for wide area network deployment, and the application area is more suitable for wide deployment. A feature application such as shared bicycles is more suitable for NB but not for LoRa, which is more like the relationship between 3/4G and WiFi.
LoRa: The base station needs to be managed by itself. It can be compared to a WIFI router at home and a mobile phone connected to WIFI to surf the Internet.
NB-IoT: The base station operator has already built it for you. You only need to pay for the transmission. The data goes through the operator's network. It can be compared to the current mobile phone 3/4G Internet access
LoRa and SigFox appeared earlier and were more mature than LPWA technology based on licensed spectrum, and could also be commercialized on a large scale, which could meet the needs of some users at that time, so they were chosen by operators. In the market, LPWA technologies based on unlicensed spectrum are mainly LoRa and SigFox.
With the advancement and development of technology, in 2016, two technologies, NB-IoT and eMTC, appeared, and both technologies adopted unified 3GPP standards to extend the Internet of Things. This technology has the attributes of an industry standard, is open, and the technological direction adopted is to gradually evolve to 5G, and the standard will continue to improve and evolve.
3. IC card table
It is also called a prepaid meter, which is paid first and then used.
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