RS-485 communication interface polarity detection device, method and chip

A technology of RS-485 and communication interface, which is applied in the field of RS-485 communication interface chip, can solve problems such as difficult implementation and complicated polarity detection method, and achieve the effect of increasing cost

Active Publication Date: 2013-12-04
HANGZHOU VANGO TECH
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Problems solved by technology

[0027] The purpose of the present invention is to provide a RS-485 communication interface polarity detection device, method and RS-485 co

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  • RS-485 communication interface polarity detection device, method and chip
  • RS-485 communication interface polarity detection device, method and chip
  • RS-485 communication interface polarity detection device, method and chip

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Embodiment Construction

[0044] The technical solution for implementing the present invention can be divided into two parts: detection and adjustment.

[0045] The polarity detection method can refer to image 3 , Figure 4 and Figure 5 As shown, the specific process is as follows.

[0046] When the RS-485 interface communicates, the differential signal mode on the A and B signal lines is defined by the RS-485 communication protocol. During communication, the start bit of each frame of data is '0', and the logic level of the subsequent address bits, data bits, and parity bits depends on the specific data, and both '0' and '1' are possible. The stop bit is '1' and may last for a long time. Therefore, two time periods can be defined, one is the duration of the start bit, address bit, data bit and parity bit, which is defined as T1. The maximum value of T1 occurs when the number of start bits, address bits, data bits and parity bits is the largest, and the communication code rate is the slowest. As...

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Abstract

The invention discloses an RS-485 communication interface polarity detection device, an RS-485 communication interface polarity detection method and an RS-485 communication interface chip, wherein the RS-485 communication interface polarity detection device includes a clock circuit and a polarity detection circuit; the polarity detection circuit times signals received by a receiver unit through using a clock provided by the clock circuit, and judges the polarity of an RS-485 communication interface according to the lasting time of '' 1 '' or '' 0 '' electric levels in the signals; and therefore, the RS-485 communication interface chip can be adjusted inside, and with no cost increased and no performance index modified, requirements of a non-polarity RS-485 system can be satisfied.

Description

【Technical field】 [0001] The invention belongs to the field of electric devices, and relates to an RS-485 communication interface polarity detection device, a method and an RS-485 communication interface chip. 【Background technique】 [0002] RS-485 is an interface standard, and it has the following characteristics that make it the preferred serial interface standard: [0003] 1) The RS-485 interface uses a combination of a balanced driver and a differential receiver, which enhances the ability to resist common-mode interference, that is, it has good anti-noise interference. [0004] 2) The maximum data transmission rate of the RS-485 interface is 10Mbps. [0005] 3) The standard value of the maximum transmission distance of the RS-485 interface is 4000 feet (about 1219 meters), which can actually reach 3000 meters [0006] 4) The RS-485 interface allows up to 256 transceivers to be connected on the bus, so that users can easily form a network using the RS-485 interface ...

Claims

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Application Information

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IPC IPC(8): G01R31/02
Inventor 钟书鹏姜学平
Owner HANGZHOU VANGO TECH
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