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Flowmeter networking, such as electromagnetic flowmeters, vortex flowmeters, turbine flowmeters, etc., is an instrument suitable for use in long-distance measurement and control. It is the result of instrumental measurement and control skills, modern computer skills, network communication skills, and microelectronics skills. . Networked devices can perform active measurement, manipulation, storage, and visualization of measurement results and manipulations of related physical quantities as defined by normal instruments; together they have important network application characteristics. Authorized instrument operators can use the Internet to make long-distance connections. Perform functional operations on the instrument, obtain measurement results, and monitor the instrument in real time, set parameters and fault diagnosis, and manipulate it to dynamically publish information on the Internet. They are the same as the computers and become independent nodes in the network. It is very convenient to connect directly with the nearest network communication cable, and “plug and play†to send the on-site test data directly to the Internet; the user goes through the reader or fits. The standard application program can read this information in real time (including processed data, instrument panel drawings, etc.).
The characteristics of networked instruments: According to the Internet's measurement and control system, front-end modules not only end signal collection and manipulation, but also co-ordinate the analysis and transmission of signals, because it is supported by a powerful microprocessor and an embedded operating system. . On this platform, the user can easily complete the addition, deletion, and selection of different network transmission methods for various measurement function modules. Second, according to the most significant feature of the Internet's measurement and control system, the method of signal transmission has changed. According to the monitoring and control system of the Internet, the transmission of measurement and control signals is based on the public Internet. With front-end embedded modules, the system's safe and useful transmission of measured data becomes possible. Furthermore, according to the Internet's measurement and control system, the expression and output of measured results have also been greatly improved. On the one hand, regardless of where they are, users can easily read various real-time data through the client and understand the device. The work situation; On the other hand, in the client's control center, the intelligent software and database system can be invoked to analyze the measured results, as well as to provide the operator with instructions or decision plans to help.
The method of accessing the Internet or Ethernet: The planning method for networked instrumentation is to embed the embedded system into the instrumentation and make it the center of measurement and control. In general, there are three ways to connect an embedded instrument to the Internet or Ethernet to a network instrument:
(1) The 32-bit advanced MCU constitutes an embedded device. Because it can be used for capital expansion, all TCP/IP protocol suites can be implemented in the system. Therefore, it can become a network device directly connected to the Internet, but it is difficult to develop. ;
(2) For embedded devices consisting of a low-order 8-bit machine, use a dedicated network (such as RS-232, RS-485, Profibus, etc.) to connect a number of embedded devices to the PC and use the PC as a gateway, and the PC should The information on the network is transformed into TCP/IP protocol packets, sent to the Internet for information sharing, but a PC must be specially configured for protocol conversion.
(3) The 8-bit single-chip microcomputer constitutes an embedded networked instrument that directly accesses the Internet. The advantage of this program is that it can use the measurement equipment based on 8-bit single-chip microcomputers, plus the network chip, directly driving the network interface chip, but occupying capital. (ROM, RAM, CPU) is more, request the one-chip computer to meet the fast operating speed.
Interface chip supporting the network: The network interface chip uses the RTL8019AS from RELTEK. Because of its excellent function and low price quotation, it is an ideal chip for Ethernet communication.
(1) The main function
Meets Ethernet II and IEEE802.3 standards; for full-duplex communication interface, transceivers can reach 10Mbps together; built-in 16K SRAM for transceiver buffers, reduces speed requests to the host processor; supports 8/16-bit data bus, 8 suspension request lines and 16 I/O base address selections; ability to complete physical frame composition, codec, CRC composition and verification, data transmission and reception, etc., can be sent and received on the twisted pair via the switch .
(2) Internal structure
RTL8019AS can be divided into long-distance DMA interface, local DMA interface, MAC (Media Access Control) logic, data encoding and decoding logic and other ports. The long-distance DMA interface refers to the one-chip computer reads and writes the bus of RTL8019AS internal RAM, namely the interface part of ISA bus line. The single-chip transceiver only needs long-distance DMA operations. The local DMA interface is the connection channel between the RTL8019AS and the network cable, which completes the data exchange between the controller and the network cable.
(3) Internal RAM Address Space Allocation
The RTL8019AS has two internal RAM areas. A 16K-byte address is 0x4000~0x7fff; a 32-byte address is 0x0000~0x001f. The RAM is stored page by page, one page per 256 bytes. Usually, the first 12 pages of RAM (ie, 0x4000~0x4bff) are used as the send buffer, and the last 52 pages (ie, 0x4c00~0x7fff) are used as the accept buffer. The 0th page address is 0x0000~0x001f, used to store Ethernet physical address.
(4) I/O address allocation
The RTL8019AS has a 32-bit input/output address with an address offset of 00H~1FH. In the meantime, 00H~0FH total 16 addresses are register addresses. The registers are divided into four pages: PAGE0, PAGE1, PAGE2, PAGE3. The pages to be visited are determined by the PS1 and PS0 bits in the CR (Command Register Command Register) of the RTL8019AS. The long-distance DMA address contains 10H~17H and can be used as a long-distance DMA port, as long as one of them can be used. The reset port contains 8 addresses, 18H~1FH, with the same function and is used to reset the RTL8019AS.
After-sales and warranty
All products supplied by Duo Qin Instrument (Shanghai) Co., Ltd.:
All products are warranted for 2 years;
Provide free telephone consultation, guide installation and commissioning services;
Negotiate door-to-door installation, commissioning and other issues, and only charge reasonable travel expenses;
Large amount can be free to guide the installation, commissioning;
Service tenet: No matter how long the product is used, as long as you find us, we will solve all problems for you until you are satisfied. We believe that our experience in the flow meter industry for more than 10 years can bring you satisfactory service.
Dochin Instrument (Shanghai) Co., Ltd. Main products: electromagnetic flowmeter, vortex flowmeter, turbine flowmeter, ultrasonic flowmeter, V- cone flowmeter, metal rotor flowmeter, oval gear flowmeter, ultrasonic cold heat meter and (Explosion-proof type) quantitative control system and other products, your needs and satisfaction is always our pursuit, welcome to call the communication consulting.
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