485 Output both ends (A 10. B A) there is no change in the voltage output, is abnormal, because the computer industrial computer and pLC they collect a variety of signals and information, through the computer, pLC collection and shaping, through coding, converted into control and digital signal, and then through the 485 chip for loading amplification output (A 10. B A) the 5v variable voltage, through the two core wire can be connected to transmit multiple control and display mechanisms, 485 (A 10. B a) The advantages of transmission anti-interference ability is strong, the transmission distance is far, the control point is more. If there is no voltage change at both ends of the 485 transmission, the 485 chip is damaged.
If there is no voltage between the two output terminals, it is abnormal.