Description
PLC的程序一般不能按事先设定的循环周期运行。PLC程序是从头到尾执行一次后又从头开始执行。（现在一些新型PLC有所改进，不过对任务周期的数量还是有限制）而DCS可以设定任务周期。比如，快速任务等。同样是传感器的采样，压力传感器的变化时间很短，我们可以用200ms的任务周期采样，而温度传感器的滞后时间很大，我们可以用2s的任务周期采样。这样，DCS可以合理的调度控制器的资源。
Cisco IGX 8410RM-AC 2x NPM-32 WAN Switch
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Lucent Avaya P333R-LB 24 Port Load Balancing Switch
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New Surplus Nortel Passport 8608GBIC DS1404015 8x GBIC
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Juniper P-4FE-TX 4 Port Fast Ethernet PIC TX M20 M40
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New Surplus Nortel 8348TX DS1404077 Routing Sw 10/100TX
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Juniper PE-10CHE1-RJ48 10PORT CHANNELIZED E1 IPI6146EAA
