ABB PNI800 处理器单元 PNI800A 网络接口模块

ABB PNI800 处理器单元 PNI800A 网络接口模块

ABB PNI800 处理器单元 PNI800A 网络接口模块

DCS是从传统的仪表盘发展而来。因此，DCS从先天性来说较为侧重仪表的控制。PLC从传统的继电器回路发展而来的，最初的PLC甚至没有模拟量的处理能力。因此，PLC从开始就强调的是逻辑运算能力。

DCS在发展的过程中，虽然是各厂家自成体系，但大多数系统的内部通讯协议不尽相同，但操作级的网络平台都选用了以太网络，只要网络到的地方，就可以随意增减节点数量和布置节点位置。另外，新型的通用操作站，基于windows系统的OPC、DDE等开放协议，各系统也可以很方便的通讯，以实现资源共享。

对于PLC系统来说，很少有扩展的需求，因为PLC系统一般针对于设备来使用。一般来讲，PLC少有兼容性的要求，比如两个或两个以上的系统要求资源共享，对PLC来讲也是很困难的事。而且PLC一般都采用专用的网络结构，比如西门子的MFI总线型网络，甚至增加一台操作员站都不容易或成本很高。但随着科技的发展，PLC的可拓展性也越来越强。

ABB PNI800 处理器单元 PNI800A 网络接口模块

DCS evolved from traditional dashboards. Therefore, DCS is more focused on the control of instruments from the congenital point of view. PLC developed from the traditional relay circuit, the original PLC did not even have analog processing capacity. Therefore, the PLC has emphasized logical computing power from the beginning.

DCS in the process of development, although the manufacturers are their own system, but most of the internal communication protocols of the system are not the same, but the network platform of the operation level is selected Ethernet network, as long as the network to the place, you can arbitrarily increase or decrease the number of nodes and layout node location. In addition, the new general operation station, based on the windows system OPC, DDE and other open protocols, the system can also be very convenient communication, in order to achieve resource sharing.

For PLC systems, there is little need for expansion, because PLC systems are generally used for equipment. In general, there are few compatibility requirements for PLC, such as two or more systems requiring resource sharing, which is also very difficult for PLC. And PLC generally use a dedicated network structure, such as Siemens' MFI bus network, and even adding an operator station is not easy or costly. However, with the development of science and technology, the scalability of PLC is becoming more and more strong.