Description
PLC的快速信号在慢速反应的DCS的操作站上显示。经测定,一个微动开关的动作要经过几秒以上的时间才能在DCS的操作站上表现出来。有的DCS甚至需要8秒。另一个互联办法是把PLC的个别信号用硬线连到DCS的输入板上,这样输入的点数很少,成本比较高。有的DCS在DCS网络上设计一个结点,该结点专门用来读取PLC的信号。把PLC的信号送入DCS的网络是比较困难的。缺点是开发接口的费用很高。即使开发成功,接口也经常发生故障。一个典型例子是燃汽轮机和锅炉联合发电的电厂,燃汽轮机从美国或其它国家进口,燃汽轮机的控制系统(PLC)和主设备一起配成,而锅炉的控制系统由用户自己选配,用户很想把两者的信息在一个操作站上显示。为开发这个操作站,开发费用在几万美金以上。即使开发成功,也经常发生故障。
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