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Method and system for polarity detection of rs-485 interface based on electric energy meter communication protocol

A technology of RS-485 and polarity detection, applied in the direction of data exchange through path configuration, bus network, etc., can solve the problems of easy reverse polarity and complicated polarity detection methods, and achieve convenient construction and later maintenance, Realize the effect of simple and reliable, simple and reliable networking

Active Publication Date: 2016-04-20
BEIJING SMARTCHIP MICROELECTRONICS TECH COMPANY +3
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Solve the problem that the existing polarity detection method is too complicated and the polarity is easily reversed

Method used

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  • Method and system for polarity detection of rs-485 interface based on electric energy meter communication protocol
  • Method and system for polarity detection of rs-485 interface based on electric energy meter communication protocol
  • Method and system for polarity detection of rs-485 interface based on electric energy meter communication protocol

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Embodiment

[0061] like image 3 As shown, the polarity detection method flow process provided by the invention is:

[0062] 1. When the RS-485 interface communicates, according to the requirements of the multi-function energy meter protocol (DL / 645-1997), the leading byte 0xfe and the frame header 0x68 should be transmitted first during communication, and then the address bits, data bits and so on.

[0063] 2. If the leading byte 0xfe is used to judge, the probability of misjudgment is high, so the frame header 0x68 is used to judge, that is, the RS-485 receiver receives the differential signal between A and B and stores it in an 8-bit shift register. The data in the register is judged on the falling edge of the clock. If the data in the register is 0x68, it means that the polarity detection is correct; if the data in the register is 0x79, it means that the polarity detection is wrong; if the data in the register is not 0x68 or 0x97, It means that the data has not yet been transmitted, ...

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Abstract

The invention relates to an RS-485 interface polarity detecting method and system based on an electric energy meter communication protocol. The method comprises the steps: (1) storing signals received by an RS-485 receiver in a register, (2) judging stored data, (3) switching a polarity switch, and (4) finishing the detection and starting to receive following data. The system comprises phase inverters, a receiver unit, a transmitter unit and a polarity detecting unit. The polarity detecting unit comprises a clock circuit, a polarity detecting circuit and the shifting register. A signal input pin of the transmitter unit is connected with one phase inverter. A signal input pin of the receiver unit is connected with the other phase inverter. When networking of an RS-485 module is performed, A and B polarities can be changed at random; a pull-up resistor and a pull-down resistor are only additionally arranged on a concentrator or a collector, and the networking is easy and reliable.

Description

technical field [0001] The invention relates to an electrical device, in particular to a method and a system for detecting the polarity of an RS-485 interface based on the communication protocol of an electric energy meter. Background technique [0002] In the electric power industry, the communication protocol of the multi-function electric energy meter (DL / T645-1997) is generally used as the remote control communication protocol of the electric meter. [0003] RS-485 is an interface standard that has the following characteristics that make it the preferred serial interface standard: [0004] 1) The level of the RS-485 interface is low, which is not easy to damage the chip of the interface circuit, and the level is compatible with the TTL level, which can be easily connected to the TTL circuit. [0005] 2) The maximum data transmission rate of the RS-485 interface is 10Mbps. [0006] 3) The maximum communication distance of the RS-485 interface is 4000 feet (about 1219 me...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04L12/40
Inventor 胡鹏飞袁玉湘姜学平
Owner BEIJING SMARTCHIP MICROELECTRONICS TECH COMPANY