For a system with the same number of i/o points,the cost of using plc is lower than that of dcs(about 40%can be saved).PLC does not have a dedicated operating station,and the software and hardware it uses are common,so the maintenance cost is much lower than that of dcs.If the controlled object is mainly equipment chain and relatively few loops,it is more appropriate to use PLC.
相同i/o点数的系统，用plc比用dcs，其成本要低一些（大约能省40%左右）。plc没有专用操作站，它用的软件和硬件都是通用的，所以维护成本比dcs要低很多。如果被控对象主要是设备连锁、回路相对很少，采用plc较为合适。
HP/Agilent 8753C/SN:3317U01887 Network Analyzer, 300 kH
HP/Agilent 8591C/SN:3916A03491 Cable TV Spectrum Analyz
HP/Agilent 11793A Microwave Converter
HP/Agilent 8591C Cable TV Spectrum Analyzer, 1 MHz to 1
HP/Agilent 8648D/SN:3847A02898 Signal Generator,9 KHz –
HP/Agilent 8970B Noise Figure Meter, 10 MHz to 2047 MHz
