Signal switching is performed on cards that are inserted into the mainframe rack. 信号切换是在插入到主机的开关卡上完成的。
Unlike switching current signals to an ammeter, switching a current source to multiple loads usually does not require maintaining the current path at all times. 与将多个电流信号切换至单台安培表不同，将一个电流源切换至多个负载通常不需要任何时候到维持电流通路的连续性。
