RS-232 is also called serial port, or serial port for short. It is a serial communication technology standard. Most desktop computers now have an RS-232 port. RS-232 port mechanical plug is generally DB-9 pin, there are 9 signal lines, of which there are three commonly used signal lines: TXD (send), RXD (close) and GND (ground). The TXD is normally at a voltage of approximately -9V (level 1); as a digital signal, the TXD has another level state of +9V (level 0). When two RS-232 ports communicate with each other, TXD receives the RXD of the other party, RXD receives the other party's TXD, and GND contacts the other party's GND. Most microcontrollers have a serial port. The pins are TX and RX and GND. The TX of the microcontroller is usually voltage, about +5V (level 1); as a digital signal, TX. There is another level 0V (Level 0). When the two serial ports of the single chip communicate with each other, the TX receives the RX of the other party, and the RX receives the TX of the other party, and the GND is connected to the GND of the other party. The computer's RS-232 port can be converted to a microcontroller serial port using a level shifter. The typical integrated circuit model is MAX232.
Isolation voltage, also called discharge voltage or breakdown voltage, refers to a voltage difference between two mutually isolated sides. When the voltage difference is large enough to reach a certain value, the isolated two sides will produce discharge or breakdown without isolation.
The relationship between the air breakdown voltage and the interelectrode distance under the conditions of a uniform electric field, a gas pressure of 1 atm, and a temperature of 20°C. The larger the distance, the greater the isolation voltage, which is basically a proportional relationship, approximately 30 kV/cm. The figure can be found out, 1cm breakdown voltage is 30kV, 5cm breakdown voltage is 150kV.
RS-232 is a commonly used serial communication interface. Two RS-232 devices that communicate with each other sometimes need to isolate the RS-232 port. The advantages are: 1. Ground potential isolation. Two RS-232 devices may use different power supplies. The GND and RS-232 of this power supply GND is generally the same (not isolated). If the RS-232 ports of these two machines are directly connected, then it is equivalent to connect the GND of the two machines' power together. If the potentials of the GND grounds of the two power supplies themselves have a potential difference, it will cause RS. Damage to the -232 interface even burned the machine. 2. Optical isolation or magnetic isolation is equivalent to a filter, so it can filter out high-frequency RS-232 interference signals and increase the anti-interference ability of RS-232.
At present, the electrical isolation of RS-232 serial port adopts optocoupler or magnetic coupler. Since the optocoupler or the magnetocoupler is an integrated circuit and the internal space of the integrated circuit is small, the isolation voltage is low. Our commonly used optocouplers are available in standard DIP6 or DIP8 packages. The overall size is less than 8 x 8mm, and the internal silicon size is even smaller. The maximum isolation voltage is only 2500V. Magnetocoupler is also an integrated circuit, the indicator is called 6000V isolation voltage, but the actual isolation voltage is not necessarily stronger than the optocoupler. If you want to increase the isolation voltage, you cannot use optocouplers or magnetocouplers. BOSS electronic engineers tried to use fiber optics or radio frequency in order to increase the isolation voltage of RS-232. Serial port fiber optic converters are too costly and must be wired with fiber optic cables, and are not easy to use. Wireless serial converters have radio frequency interference problems and are not sufficiently reliable in industrial applications.
The RS-232 high-voltage isolator must also be an important indicator: passive. When Bosch Electronics conducts high-voltage breakdown tests on the BS232 series of products, if an active isolator is used, it is often the case that the transformer of the power supply itself is isolated by a low voltage (1KV). Bosch Electronics' product improvement plans are as follows: 1. The active high-speed RS-232 isolator uses the RS-232/5V power supply/RS-232 three-way isolation scheme, that is, the power supply and both sides of the RS-232 are Isolated and powered by a separate power supply. 2. Use passive RS-232 isolator, especially isolator with space isolation technology.
Bo Shi Electronic's BS232K RS-232 Space Isolator is a new RS-232 isolator. It does not use optocoupler nor magnetocoupler, but separates two RS-232 ports in space. 1cm or more. Divided into two layers above and below in this 1cm space, the propagation is the polarized light of the laser, and in fact there is nothing in this space except air. The larger the distance, the greater the isolation voltage, which is basically a positive proportional relationship, about 30 kV/cm, so the BS232K can achieve 30 KV voltage isolation of the RS-232 serial port without power supply.
The shape of the BS232K is DB-9 (bore)/DB-9 (needle) adapter box size, and 1 cm of isolated space can be seen from the RS-232 isolated from the optional brown casing. Bo Shi also can provide custom 5cm isolation space, isolated 150KV RS-232 passive space separator.
If the hole holder end of the BS232K type RS-232 space isolator is directly connected to the RS-232 socket (pin holder) of a data terminal equipment (DTE) such as a PC, the other end (pin holder) of the BS232K type is equivalent to one. New electrically isolated RS-232 port. If the end of the base of the BS232K type RS-232 space isolator is directly plugged into the RS-232 socket (hole seat) of a data communication equipment (DCE) such as MODEM, the other end of the BS232K type (hole seat) is equivalent to a new one. Electrically isolated RS-232 port. Note: The BS232K only isolates and transmits only the RS-232 receiver, transmitter, and receiver.
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