APL field switch with automatic protocol detection

A protocol detection circuit for detecting a field device protocol of a field device attached to a channel having a data line is sequentially connected to the data line through a controller that communicates with the field device through the protocol detection circuit. After the protocol detection is completed, the protocol detection circuit is disconnected from the field device. The channel may be one of a plurality of channels; the controller may also connect and disconnect the protocol detection circuit to and from one channel, whereby the protocol detection circuit may be used with any channel. After identifying a protocol of the field device, a protocol adapter may be inserted into the channel to enable data conversion between the field device protocol and another protocol used by the channel for data transmission. 用于检测附接到具有数据线的通道的现场设备的现场设备协议的协议检测电路通过控制器顺序地连接到数据线，该控制器通过协议检测电路与现场设备通信。协议检测完成之后，协议检测电路与现场设备断开连接。通道可以是多个通道中的一个；控制器还可以将协议检测电路与一个通道连接和断开连接，由此协议检测电路可以与任何通道一起使用。在标识出现场设备的协议之后，可以将协议适配器插入到通道中，以实现现场设备协议