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About MAX232 Experts please come in [Copy link]

First of all, the company produces instruments. The signal processing part of the instrument is controlled by a single-chip microcomputer, and then the data is sent to the computer through MAX232. The software on the computer is written in VB, and there is no data processing, just displaying the data. I would like to ask, why does the computer sometimes freeze when the instrument is connected to the computer? Even the COM port of the computer is burned when connected? In addition, the single-chip microcomputer and MAX232 are normal, but the connection between the instrument and the computer is intermittent? Today's serial communication is very mature, will there be a current shock problem?

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There are many cases of serial ports burning out. I have encountered it twice. Just replace the serial port chip and it will be fine  Details Published on 2013-12-24 08:31
 

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The MAX232 chip plays the role of RS232 and TTL level conversion, so it won't burn out normally?! Did you get the power from the COM port of the computer? Generally, just connect RX and TX! The other pins can be left empty, it's very stable, and I haven't heard of anyone burning out the COM port of a computer.
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There are many cases where the serial port is burned. I have encountered it twice. Just replace the serial port chip.  Details Published on 2013-12-24 08:31
 
 

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If it burns, the possible reasons are as follows: 1. After your instrument is powered on, the voltage of RX and TX connected to the PC is not TTL level, that is, it may be greater than 5V (or even greater than 9V), which may cause the computer com port to burn. 2. If max232 is directly connected to the mcu, check whether the pin status of the mcu is high or low after powering on. And analyze its impact on max232. 3. Sort out your thoughts, use a logic analyzer to connect the port line connected to the pc end, and observe if there is any abnormality. Generally, there will be no problem on the computer side, it is probably that your max232 side is not fixed properly.
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It is best to turn off the power when plugging and unplugging the serial port. Do not hot-plug, otherwise it is easy to burn the serial port: For example, when plugging and unplugging, sometimes TXD is connected to the computer serial port first, and GND is connected later, resulting in a voltage difference greater than 12V, causing damage to the serial port. So the above problems can also be caused by your frequent hot plugging
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First of all, the switching power supply that powers the circuit board outputs a stable +5v voltage. There is no problem. The 16th and 15th pins of MAX232 are connected to the +5v voltage and ground, not the power from the com port. The 13th and 14th pins of max232 are directly connected to the computer through the serial port line, and the 11th and 12th pins are directly connected to the mcu. The connection between the instrument and the computer is not generally faulty, only a few instruments will have this problem, but these few instruments give me a headache. Thank you sunnylong for your advice. If there are other possibilities, please tell me! Thank you!
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Are pins 13 and 14 directly connected to the computer via a serial port line? Add a 100 ohm resistor between pins 13 and 14 and the output to the serial port to limit the current. This should prevent the serial port of the device from being burned out.
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Oh, it's a problem with the finished product! I thought it was a problem in your development process! As above.
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Our company sells MAX232. If you have any needs, please contact me at QQ313431273. Email: pdf13143468372@163.com

4902.jpg (18.47 KB, downloads: 9)

4902.jpg
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I'll send you a simple picture, take a look, it's absolutely fine
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Sometimes it is the communication chip of the PC host, or your 232 is broken. You cannot connect more than 4 232 chips in parallel, which will cause the chips to burn out. If you send multiple addresses in the form of a bus, you can use two transistors to replace the 232 chip. It is very useful. I have encountered it.
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I burned mine once, and now I don't dare to try it again.
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Mine burned once, and both COM ports on a computer were destroyed. Now I don't dare to try again.
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No way, that's too much, how many volts do you use to power the MAX232???
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Is the voltage unstable? @The computer will explode^_^
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The five capacitors are 1uF electrolytic capacitors, but the voltage measured at the second and sixth pins of max232 is +5.64V and -5.42V.

When performing serial communication, max232 heats up.

What's going on? Please help me! ~
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Please send out this part of your circuit, otherwise it is impossible to judge
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Is your connection correct? These two pins should be at +10V and -10V.
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Add coupling capacitors to RX and TX
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There are so many stories about MAX232? I have never heard of it before. The only time I heard someone burnt out the 232 interface was because his system was made of RC and voltage reduction. It would be strange if it didn't burn out. I used 0.1uF capacitors, and I have been using them for 3 years, and all the products have never had any problems.
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The same thing happened to me.
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