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Anonymous users2024-02-071. You can take 2 converters.
Port 485 is docked, and the end of 232 is connected to the 2 serial ports of the computer, and then use the serial port debugging tool to send it to see if the reception is normal.
2. If it is the whole line, you can exclude the 485 converter first, and then use a multimeter.
The short circuit method measures the quality of the 485 communication line. The best way is to form a serial communication line, which can communicate normally, and the RS232-485 converter must have no problem.
The 485 communication line adopts the principle of differential mode transmission, so it must take twisted pair.
The network cable is composed of 4 pairs of twisted pairs, so take the network cable, choose one of the pairs, be careful not to be self-defeating, the network cable is a pair of strands, and the method of trying to thicken the line to improve the quality of communication is counterproductive).
Some construction personnel draw for a convenient time, and put ordinary power cords or parallel wires.
It is quite dangerous to do 485 communication lines, because the longer the distance between these parallel lines, the greater the interference generated by the line itself, and the worse the anti-interference ability, until it is impossible to communicate.
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Anonymous users2024-02-061. You can take 2 converters to dock with port 485, and connect 2 serial ports to the computer at the end of 232, and then use the serial port debugging tool to send it to see if the reception is normal.
2. If it is the whole line, you first exclude the 485 converter, and then use the multimeter short circuit method to measure the quality of the 485 communication line. The best way is to form a serial communication line, which can communicate normally, and there is definitely no problem with the RS232-485 converter.
485 communication line Huiyin Road adopts the principle of differential mode transmission, so it is necessary to take the twisted pair (the network cable is composed of 4 pairs of twisted pairs, so take the network cable, choose one of the pairs, do not be self-defeating, the network cable is a pair of shares, and the method of trying to thicken the line to improve the quality of communication is counterproductive).
It is quite dangerous for some construction personnel to make 485 communication lines for the convenience of ordinary power lines or parallel banquet lines, because the longer the distance between these parallel lines, the greater the interference generated by the line itself, and the worse the anti-interference ability, until it is impossible to communicate.
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Anonymous users2024-02-05Broken wire measurement method: using the on-off test function of the multimeter, the red and black watch pens are placed on both ends of the side line, if the conduction is not broken, the non-conduction wire may be broken, (it may also be a mixed wire).
Mixed line test method: basically the same as the above, also using the on-off test.
If your multimeter does not have the on-off test function, you can use the resistance level, and the resistance value obtained by the test is very small, which is on, and it is off anyway.
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Anonymous users2024-02-04Jump the multimeter to the diode or resistance setting.
This method is called "school line".
One person will connect one end to the ground, and the other person will use two wires of the watch pen at the other end to measure (by color, one watch pen is grounded, and the other watch pen is in contact with the wire according to the color), and only one is through. The line number of the pass will be marked with all 9 lines at a time.
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Anonymous users2024-02-03The first step in learning the multimeter is to master the use of buzzer and diode gear, and most of the maintenance measurements in life can be used.
The bad part is the transformer, the transformer in the circuit can be used for the audio output transformer for transistor radio, the secondary is used as the primary of the step-up transformer, the tap in the middle of the primary is not used, and the taps at both ends are used as the secondary of the step-up transformer. If you can't find a suitable transformer, you can also use the silicon steel sheet of the radio output transformer to make your own, and use a high-strength enameled wire with a diameter of 0 25mm for 110 turns for the primary stage, and a high-strength enameled wire with a diameter of 0 21mm for 520 turns for the secondary. A layer of insulating paper should be added between the primary stages, and attention should be paid to the eponymous end of the primary stage coil. >>>More
The principle and maintenance of pointer multimeter, the role of components, maintenance methods, and internal structure are explained in detail.
Turn the digital multimeter to the current gear, take the red and black stylus to the two sides of the contact switch under the float, there is a current display to prove that it is energized, and there is no current display to the line is faulty.
This is the IGBT produced by "Fairchild", 25A1200V, according to the pins shown below. >>>More
Friend, first use the resistance gear of the multimeter by 10k gear to measure the insulation resistance of the motor binding post to the ground, if it is very large, then the motor is not grounded, if it is very small, then the motor winding coil or lead wire is grounded, that is, burned. In addition, use the multimeter resistance gear by 1 gear to measure the resistance between the windings of each phase of the binding post, if the resistance is very low, and the three phases are not the same, then it means that there is a breakdown phenomenon in the winding, if they are almost the same, then it means that it is good.