S800、S900是用于过程控制站的分布式I/0，它们通过Prof ibusDP现场总线与其所属的控制器
通信，既可以安装在控制室，也可以安装在现场以尽量接近现场变送器和执行器，从而 节省电缆并
减少安装费用。
S800 1/0及s900 I/0 具有以下优点:
●灵活性:对安装数量没有限制，可小数量安装，也可大量安装，可以安装在室内，也可安装在室
外，可以安装在墙上，也可安装在机柜中。
●模块化:可一步一步扩展，不会因自身限制而影响系统扩展。
●经济性:节省硬件，电缆，从而节省安装及维护费用.
●可靠性:因其自诊断及冗余等特性，可平滑的实现自动切换。
Glossary
Process station:
This term is used to describe AC800F controllers (field controllers) and rack-mounted controllers. A process station can be designed to be redundant
configuration and non-redundant configuration.
AC800F :
This term is used to describe the AC800F Field Controller type of process station. A redundant process station consists of 2
AC800F controller.
Rack mounted process station:
This term is used to describe a rack-mounted type of process station. A redundant process station contains 2 rack-mounted CPUs.
This term is used to describe a single, non-redundant process station.
In the investment of modern automation system, due to the hardware equipment
