AC-Coupled RS-485

485总线节点数据跟单位负载有关，单位负载的定义则是根据标准的485总线接收器的输入阻抗（12Kohm）来定义的，485总线负载电阻Rload不能大于375欧姆，所以标准的RS485总线能够驱动32个单位负载（即32个12Kohm并联）。像有些收发器datasheet中会给出1/4 unit load，那么节点数就为128个。

AC 耦合只是提供了一个数据链路的功能隔离吧，user's guide中给出的AC耦合的优点：

 AC-coupling allows transceivers to operate with large common-mode offsets, enabling long-distance communication without routing an additional ground wire. AC-coupling also protects the transceivers against high-voltage DC faults (for example, if the differential bus is shorted to a power supply). This protection is useful in industrial applications that require data transfers across long distances with a minimum number of wires.

你好，那请问，下面第二个图中是RS485全双工，是否能直接将AB线断开，通过电容耦合方式（类似于AC耦合半双工方案）隔开实现AC耦合隔离全双工？谢谢。