CN102193893A - Serial port 232/422 signal output switching method - Google Patents

Abstract

The invention provides a serial port 232/422 signal output switching method. The serial port 232/422 signal output switching method comprises the following steps of: jointing interface functions A and B which are formed on upper computer software with corresponding commands in a singlechip program; controlling output states of corresponding pin signals by using the commands of the singlechip program and controlling switching of a peripheral logic circuit so as to realize different processes on a standard signal output from the serial port; and finally realizing switching between an RS232 signal and an RS422 signal which are output from the serial port. Compared with the prior art, the method has a simple operation; and corresponding switching operation can be realized by simply clicking a mouse by calling control under an operating system instead of powering off a host and dismantling a chassis.

Description

A kind of serial ports 232/422 signal output switching method

 

Technical field

The present invention relates to that RS232, RS422 communications protocol, single-chip microcomputer use, C programmer is write, circuit board principle design and fabric swatch, mainly be applied to computing machine, communication and association area, specifically a kind of serial ports 232/422 signal output switching method.

Background technology

Present conventional mainboard is externally exported rs 232 serial interface signal will realize that the blocked operation of exporting between 232 signals and output 422 signals is more loaded down with trivial details, needs to divide following several steps to carry out usually:

1) host computer is carried out power operation, take cabinet apart;

2), on mainboard, find the respective patch cord group, manual operation jumper cap, short circuit respective patch cord signal according to motherboard manual;

3) re-power to mainboard, whether the checking operation of doing is correct, recovers computer housing.

Summary of the invention

The purpose of this invention is to provide a kind of serial ports 232/422 signal output switching method.Under X86 framework operating system, need not outage and dismounting mainframe box, in mainboard (host computer) normal operating conditions, realize the quick switching between mainboard serial ports output RS232 signal and the RS422 signal.

The objective of the invention is to realize in the following manner, adopt being used of upper computer software, single-chip microcomputer and logical circuit, the hardware and software combination, utilize upper computer software to form different interface functions, with each interface function respectively with Single Chip Microcomputer (SCM) program in the corresponding command be connected mutually, utilize the order of Single Chip Microcomputer (SCM) program to control the output state of its respective pins signal, then control the peripheral logical circuit conversion, realization is carried out different processing to serial ports outputting standard signal, finally realizes the conversion between serial ports output RS232 and the RS422 signal.

Control procedure is divided foregrounding and consistency operation two parts, wherein:

Foregrounding: under Windwos operating system, call interface function;

Consistency operation: interface function control single chip computer program → Single Chip Microcomputer (SCM) program control single chip computer respective pins signal output state → single-chip microcomputer leg signal output state control peripheral circuit logical channel selection → different logical channel is carried out different processing → serial ports output RS232 signal or RS422 signal to serial ports outputting standard signal, and step is as follows:

Serial port of mainboard outputting standard rs 232 serial interface signal TXD2, RXD2, if this conversion of signals will be become the output of RS232 signal, then under Windows operating system, call interface function A, interface function A utilizes TXD3, RXD3 serial ports passage, its command information is passed to the Single Chip Microcomputer (SCM) program of single-chip microcomputer PCI16F87XA inside, the single-chip microcomputer internal processes takes orders, and make corresponding control action: control its output pin " 13 " CONTROL2 and be low level state output for " 0 ", be connected to the GATE control pin of N-channel MOS pipe MMBT3904 because of the CONTROL2 signal, therefore this metal-oxide-semiconductor presents " disconnection " state, therefore the TQ2-5V relay presents the not state of nature of energising, the standard TXD2 of final serial port of mainboard output, the RXD2 signal is the RS232 signal condition through the treatment conversion of MAX211E chip;

In the time above-mentioned serial ports will being converted to the output of RS422 signal, only need under Windows operating system, to call interface function B, the same control single chip computer program of this interface function B, then the output high level state that changes its pin " 13 " CONTROL2 is " 1 ", follow-up " CONTROL2 " signal of high level state that presents is with conducting metal-oxide-semiconductor MMBT3904, the TQ2-5V relay is closed because of powering on, the standard TXD2 of serial ports output, RXD2 signal be from another logical channel output, and be the RS422 signal condition by the treatment conversion of LTC485 chip.

The beneficial effects of the utility model are:

1) simple to operate, need not main frame outage and dismounting cabinet, only need under operating system, to call control, the simple click mouse just can be realized corresponding blocked operation;

2) switch rapidly, whole process only needed just can finish in 2～3 seconds, and the whole process of old-fashioned switching needs the time of 15～20min approximately, and user's time has been saved in new-type switching greatly;

3) operation is reliable, and the maloperation possibility that can effectively avoid manual switchover to exist has been protected electricity piece to greatest extent.

Description of drawings

Fig. 1 is the single chip machine controlling circuit schematic diagram;

Fig. 2 is a RS232/RS422 signal switching circuit schematic diagram;

Fig. 3 is the serial ports voltage transitions chip circuit schematic diagram after the RS232 signal switches;

Fig. 4 is a RS232/RS422 voltage commutation circuit schematic diagram.

Embodiment

Explain below with reference to Figure of description method of the present invention being done.

Serial ports 232/422 signal output switching method of the present invention, control procedure is divided foregrounding and consistency operation two parts, wherein:

Foregrounding: under Windwos operating system, call interface function;

Consistency operation: interface function control single chip computer program → Single Chip Microcomputer (SCM) program control single chip computer respective pins signal output state → single-chip microcomputer leg signal output state control peripheral circuit logical channel selection → different logical channel is carried out different processing → serial ports output RS232 signal or RS422 signal to serial ports outputting standard signal, 1～3 is specifically described in conjunction with the accompanying drawings

Serial port of mainboard outputting standard rs 232 serial interface signal TXD2, RXD2, if we want this conversion of signals is become the output of RS232 signal, then under Windows operating system, call interface function A, interface function A utilizes TXD3, RXD3 serial ports passage (information interaction passage between single-chip microcomputer and the mainboard) passes to its command information the Single Chip Microcomputer (SCM) program of single-chip microcomputer PCI16F87XA inside, the single-chip microcomputer internal processes takes orders, and make corresponding control action: control its output pin " 13 " and (CONTROL2) export for " 0 " (low level) state, be connected to the GATE control pin of N-channel MOS pipe MMBT3904 because of the CONTROL2 signal, therefore this metal-oxide-semiconductor presents " disconnection " state, therefore the TQ2-5V relay presents state of nature (not energising), the standard TXD2 of final serial port of mainboard output, the RXD2 signal is the RS232 signal condition through the treatment conversion of MAX211E chip.

When we want above-mentioned serial ports is converted to RS422 signal when output, only need under Windows operating system, to call interface function B, the same control single chip computer program of this interface function control, then changing its pin " 13 " output state (CONTROL2) is " 1 " (high level), follow-up " CONTROL2 " signal of high level state that presents is with conducting metal-oxide-semiconductor MMBT3904, the TQ2-5V relay is closed because of powering on, the standard TXD2 of serial ports output, RXD2 signal be from another logical channel output, and be the RS422 signal condition by the treatment conversion of LTC485 chip.

When we think once more above-mentioned serial ports to be converted to the output of RS232 signal, only need calling interface function A once more, specific implementation process front is by the agency of, repeats no more here.

For avoiding MAX211 chip and LTC485 chip to influence each other, we also control the input voltage of two kinds of chips in the control signal conversion, for keep and signal switches synchronously, the realization of " CONTROL2 " signal is also used in the switching of voltage, the specific implementation circuit is seen accompanying drawing 4 explanations.

If switch to the RS422 signal, this circuit can be realized the conversion process between standard serial port signal to 422 signal simultaneously, if switch to the RS232 signal, then need utilize accompanying drawing 3 circuit to realize the conversion process of standard serial port signal to 232 signal.

Claims (1)

1. serial ports 232/422 signal output switching method, it is characterized in that utilizing the interface function A and the B of upper computer software formation, with each interface function respectively with Single Chip Microcomputer (SCM) program in the corresponding command be connected mutually, utilize the order of Single Chip Microcomputer (SCM) program to control the output state of its respective pins signal, then control the peripheral logical circuit conversion, realization is carried out different processing to serial ports outputting standard signal, finally realizes the conversion between serial ports output RS232 and the RS422 signal;

Control procedure is divided foregrounding and consistency operation two parts, wherein:

Foregrounding: under Windwos operating system, call interface function;

Consistency operation: interface function control single chip computer program → Single Chip Microcomputer (SCM) program control single chip computer respective pins signal output state → single-chip microcomputer leg signal output state control peripheral circuit logical channel selection → different logical channel is carried out different processing → serial ports output RS232 signal or RS422 signal to serial ports outputting standard signal, and step is as follows:

Serial port of mainboard outputting standard rs 232 serial interface signal TXD2, RXD2, if this conversion of signals will be become the output of RS232 signal, then under Windows operating system, call interface function A, interface function A utilizes TXD3, RXD3 serial ports passage, its command information is passed to the Single Chip Microcomputer (SCM) program of single-chip microcomputer PCI16F87XA inside, the single-chip microcomputer internal processes takes orders, and make corresponding control action: control its output pin " 13 " CONTROL2 and be low level state output for " 0 ", be connected to the GATE control pin of N-channel MOS pipe MMBT3904 because of the CONTROL2 signal, therefore this metal-oxide-semiconductor presents " disconnection " state, therefore the TQ2-5V relay presents the not state of nature of energising, the standard TXD2 of final serial port of mainboard output, the RXD2 signal is the RS232 signal condition through the treatment conversion of MAX211E chip;

In the time above-mentioned serial ports will being converted to the output of RS422 signal, only need under Windows operating system, to call interface function B, the same control single chip computer program of this interface function B, then the output high level state that changes its pin " 13 " CONTROL2 is " 1 ", follow-up " CONTROL2 " signal of high level state that presents is with conducting metal-oxide-semiconductor MMBT3904, the TQ2-5V relay is closed because of powering on, the standard TXD2 of serial ports output, RXD2 signal be from another logical channel output, and be the RS422 signal condition by the treatment conversion of LTC485 chip.

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