Method for realizing serial port isolation and serial port isolating circuit

Abstract

The invention provides a method for realizing serial port isolation and a serial port isolating circuit. The method comprises the following steps: converting RS232 level signals output by an RS232 level serial port into impulse signals by a first transformer module, converting the impulse signals into transistor-transistor logic (TTL) level signals, and then outputting the TTL level signals to a TTL level serial port; according to the received TTL level signals output by the TTL level serial port, selecting to output high-frequency signals to a second transformer module or third transformer module; converting the received high-frequency signals into RS232 negative level signals by the second transformer module, converting the received high-frequency signals into RS232 positive level signals by the third transformer module, and then outputting the RS232 positive level signals to the RS232 level serial port. The invention can effectively inhibit static electricity and surge, and preventan earth loop and surge from damaging a device serial port or interfering the normal operation of the device.

Description

technical field [0001] The invention relates to the technical field of serial port signal isolation, in particular to a method for realizing serial port isolation through a transformer and a serial port isolation circuit. Background technique [0002] In the communication equipment, a serial port is generally led out on the single board as a communication port for debugging and monitoring of the single board. However, sometimes the communication equipment and the computer host do not share the same ground, or there is an uncertain potential difference between the ground planes of the two communication equipment, and when connecting the serial port, it is usually hot-swappable, and the discharge and surge between the two It is easy to cause damage to the serial port, or interfere with the normal operation of the communication equipment. [0003] In order to solve the above problems, the existing technology often uses the serial port to take power and add a photocoupler to fo...

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Problems solved by technology

[0005] Although this approach is feasible, it needs to take power from the input terminal TXD to provide RS232 level, which makes the load of TXD signal larger

In addition, the RS232 negative voltage at the input is provided by the TXD negative level signal. If the TXD signal line sends continuous bytes 0x00 (that is, TXD is positive except for the stop bit), the RS232 negative voltage provided to the RXD signal line May be insufficient

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