LED Module
27/09/2013 09:40
By this method, a certain degree of reduced signal reflection . However, in practical LED Bulb applications, due to the characteristic impedance of the transmission cable and communication baud rate and other applications related to the environment , the characteristic impedance and termination resistors not exactly equal , so we can not completely avoid signal reflections from occurring.
3, the distributed capacitance on RS-485 bus transmission performance
RS-485 transmission cable is usually more for twisted pair, twisted pair between two parallel wires will produce capacitors. Meanwhile, the cable and the earth also exist between similar small capacitor. Since RS-485 signals are transmitted on the bus by the countless " 1" and " 0 " bits composed , so when faced with such a special byte 0x01 , level "0" makes the distributed capacitance to get adequate time to charge , when the level "1 " suddenly came when the charge accumulation capacitor can not let go within a short time , thus leading to a distorted signal , thus affecting the quality of the entire data transfer .
So, on the one hand we want to try to use the distributed capacitance smaller cable that is of good quality as the communication line, the other to minimize the communication baud rate, given sufficient time to discharge capacitor .
4 , to develop a simple and reliable RS-485 communication protocol
