0 Preface
Serial RS 232 and RS 485 communication technologies have long been the communication standard commonly used in automated instruments and meters. However, in recent years, with the development of computer technology, network technology, communication technology and its application in industrial automation systems, the field of industrial automation systems, instruments and meters has accelerated the process of development toward intelligence, digitization and networking. New technologies such as power line communication technology, wireless infrared and Bluetooth communication technology, communication technology based on USB interface, fieldbus technology and embedded Internet access technology have emerged. The networked instrument based on embedded Internet access technology is a new concept put forward in recent years. It is the product of the deep integration of instrument detection technology with modern computer technology, network communication technology and microelectronic technology. The detection instrument is connected to the Internet and becomes the instrument Web site for performing measurement and control tasks. This networked instrument can automatically measure, store and display related physical quantities according to the setup program like a normal instrument, and allows authorized users to pass. The Internet remotely operates, monitors, and diagnoses the instrument. In the specific application, there are many problems, one of which is the transmission rate and system utilization is not high, this article is produced in this context.
1 TCP communication hardware interface
A typical 8-bit machine uses the TCP protocol to access the Internet's Ethernet network interface as shown in Figure 1. RTL8019AS has become the preferred Ethernet interface chip for single-chip Ethernet systems with its excellent cost performance. The chip is compliant with IEEE802.3 10Base2 and 10BaseT standards and features automatic parity detection and error correction to support full-duplex operation. As shown in Figure 1, RTL8019AS works in 8-bit jumper mode, data lines SD0~SD7 are connected to 8-bit MCU (51 series) data lines (AD0~AD7), address lines A0~A4 and 8-bit MCU address lines ( A0~A4) are connected. The read and write signals are generated by 74S04. The base address of RTL8019AS (with pin 34 (AEN)) is 0x8000H, which corresponds to the internal address 0x300H of RTL8019AS. The RTL8019AS is connected to the Ethernet through the network transformer HR901170A and RJ45 interfaces to access the internet and isolate the interference signals on the network.
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