【正文】 因?yàn)檩斎氩蓸与A段僅在輸入刷新階段進(jìn)行，PLC在一個(gè)工作周期的大部分時(shí)間是與外設(shè)隔離的，而工業(yè)現(xiàn)場(chǎng)的干擾常常是脈沖、短時(shí)間的，誤動(dòng)作將大大減小。如FX1S額定電壓AC100V—240V，而電壓允許范圍在AC85V—264V之間。使用兩個(gè)光傳感器來監(jiān)控車輛的進(jìn)出并完成計(jì)數(shù)工作，車輛進(jìn)入時(shí)經(jīng)過兩個(gè)傳感器使顯示數(shù)字加一，車輛外出時(shí)經(jīng)過兩個(gè)傳感器使顯示數(shù)字減一，但當(dāng)車輛只經(jīng)過一個(gè)傳感器時(shí)不計(jì)數(shù)。s lives. Early automatic control system relies on the relay Contactor to achieve, and its features are: simple structure, low cost, antiinterference capability, can achieve centralized control and remote control, but the introduction of fixed wiring, versatile and flexible of the poor and by the switch contacts, the low frequency contacts easily damaged, poor reliability.1969, a programmable logic controller PLC (Programmable Logic Controller), its features are: a logic control, timing, counting, and other functions, intuitive programming language used ladder diagram language, software changes convenience, versatility and flexibility good.At present, the major PLC programmable controller is a small, lowcost, standardized, highspeed, intelligent, highcapacity, in the direction of the network, and puter technology, formation of industrial control systems, distributed Control Systems DCS (Distributed Control System), fieldbus control system FCS (Field bus Control System), the PLC will enable more powerful, more reliable, more convenient to use, a wider scope. The design is based on the storage of vehicles PLC management systems, LED used two vehicles in the ga