中间层由带以太网接口的现场控制单元设备PLC组成；
The middle layer is composed of the field control unit device PLC with Ethernet interfaces.
网络接口单元（NIU）是控制计算机与通信网络进行交互的一种接口设备。
Network interface unit (NIU) is an interface device between the control computer and the communication network.
国际标准IEC60044-7/8规定了电子式互感器和二次设备的数字接口，首先提出了合并单元的定义。
IEC60044-7/8 prescribes that merging unit is the digital interface of electronic transducer and secondary equipment.
应用推荐