RS-485标准，增加了多点、双向通信能力，即允许多个发送器连接到同一条总线上，同时增加了发送器的驱动能力和冲突保护特性，扩展了总线共模范围，后命名为TIA/EIA-485-A标准。本代码用c语言编写，描述出rs485通讯原理。-RS-485 standard, multi-point, two-way communications capability, which allows multiple transmitters connected to the same bus, while increasing the drive capability of the transmitter and protection features of conflict, expands the bus common mode range, named after the The TIA/EIA-485-A Standard. The code using the c language, describe rs485 communication principle.