Serial port expanding circuit of dynamic management and control system and working method of serial port expanding circuit

Abstract

The invention provides a serial port expanding circuit of a dynamic management and control system. The serial port expanding circuit is electrically connected to RXD, TXD and I / O ports of a microprocessor. The serial port expanding circuit is characterized by being composed of an analog switch chip, a decoder chip, multiple first level switching circuits and multiple second level switching circuits, and expanding of input and output ports of the microprocessor is achieved; the first level switching circuits achieve switching of RS232 levels to TTL levels; the second level switching circuits achieve switching of the TTL levels to the RS232 levels. The invention further discloses a working method of the serial port expanding circuit. The working method involves expanding of TXD and expandingof RXD. By means of the serial port expanding circuit, expanding of the RXD and TXD ports of the microprocessor can be effectively achieved, and optocouplers are utilized to achieve switching of theTTL and RS232 levels; not only are signals reliably transmitted, but also the load capability can be improved; the serial port expanding circuit achieves optoelectronic isolation, is resistant to impact, and improves the anti-jamming performance of circuit expanding.

Description

technical field [0001] The invention belongs to the technical field of electricity and relates to an expansion circuit, in particular to a serial port expansion circuit of a dynamic management and control system and a working method thereof. Background technique [0002] In an environmental protection dynamic management and control system, it is often necessary to centrally collect, analyze and present the data of multiple online devices, and send the data of each enterprise to the central management platform for unified presentation in real time, which is convenient for the competent department to observe law enforcement. The data collected by the equipment in real time is accurately transmitted to the central platform. The online management and control system uses serial port communication to replace the analog quantity, which avoids the cumulative error caused by AD conversion and calculation. In this case, the online management and control system must have multiple RS232 ...

AI Technical Summary

Problems solved by technology

[0004] At present, the introduction of serial port expansion, such as the use of serial port expansion chip GM8125, etc., because such chips are expensive and some have been discontinued, this method can no longer meet the actual requirements.

There is a simple method of switching with a multi-way switch + RS232 chip, but with the development of microprocessors, the power supply voltage is getting lower and lower, most of them are 3.3V at present, and the internal resistance of the multi-way switch increases with the decrease of the power supply voltage. Large, causing serious signal attenuation between the microprocessor and the RS232 chip, resulting in deformation, which cannot meet the requirements of normal communication; at the same time, the current application of optocouplers in serial port expansion only plays the role of photoelectric isolation, and has not yet been able to realize TTL And RS232 level conversion function, also did not make full use of the anti-interference effect of the optocoupler

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