Power carrier communication is a unique and basic communication method for power systems. It refers to a technology that uses an existing power line to transmit analog or digital signals at high speed through a carrier. Since the widely used power line is used as the communication channel, no special maintenance channel is required, and the engineering cost is greatly reduced. This technology is widely used in street lighting control, power line security, harsh environment communication, etc., which require long distance and multi-node. However, due to the complexity and diversity of the domestic power grid, for example, when the residential power consumption peaks, a large number of loads are continuously connected and disconnected, which will cause different degrees of attenuation and interference to the carrier signal; when the carrier signal is modulated on the power line At the peak point of each AC cycle, the generated fixed pulse is very easy to lose the signal; and the existing power carrier module is expensive, and requires high-performance MCU support. Therefore, the power carrier needs a lot of research to achieve a wider application [1~2].
The purpose of this paper is to use the FSK modulation technology to realize power carrier communication, optimize the algorithm, provide a function interface, make the power carrier communication easier to use, and ensure the accuracy of communication data transmission is above 96%.
2 system overall design structure
The main function of the system is to realize that the upper computer sends data to the single-chip microcomputer through the serial port, and the single-chip microcomputer modulates the signal by FSK frequency modulation mode, and the carrier signal is coupled to the power line for signal transmission through the push-pull output circuit. At the other node of the power line, the carrier signal is restored to the original signal through the detection input circuit, the power amplifier circuit and the software algorithm, and after verification, it is sent to another host computer through the serial port. Both the signal output and the input provide a functional interface for subsequent development of user engineering [3].
3 system overall software design
　 3.1 System overall software flow chart
When the MCU starts running, after each timer, IO port and system clock are initialized, it will wait for 5s, then detect the corresponding baud rate selection IO port and power carrier mode select IO port to complete all initialization. After the program starts normal operation, the MCU will continuously receive the serial port signal and the power carrier signal, and will forward the signal after receiving the signal check.
984 controllers are available in four generic hardware classes: Large, rugged, high-performance chassis mount controllers Rugged, midrange-performance slot mount controllers, which reside in a primary housing beside 800 Series I/O Modules Host-based controllers built on various industry-standard computer cards designed to reside in and execute control logic from a host computer Low-cost, easy-to-install compact controllers, for applications with less demanding environmental and performance requirements The family approach to 984 controller design allows you to make choices based on controller capacity (the number of discrete and analog/register points available for application programming, the number of I/O drops it supports), throughput (the rate at which it solves logic and updates I/O modules), and environmental hardness (the design standards its hardware implementation must meet).
A major advantage of the family approach to 984 controller design is product compatibility. Regardless of its computational capacity, performance characteristics, or hardware implementation, each 984 controller is architecturally consistent with other 984s. The 984 instruction set (the functional capabilities of the controller, part of the system firmware stored in executive PROM) comprises logic functions common to other 984s. This means that user logic created on a midrange or high-performance unit such as a 984-685 or a 984B can be relocated to a smaller controller such as a 984-145 (assuming sufficient memory in the smaller machine) and that logic created on a smaller controller is upwardly compatible to a larger unit. As your application requirements increase, it is relatively easy to upgrade your controller hardware without having to rewrite control logic. Also, training costs and learning curves can be reduced, since users familiar with one 984 model automatically have a strong understanding of others.
Modicon PC0984 Programmable Controller
Modicon PC 0984 Programmable Controller,Communication Processor,Processor Module,CPU Module
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