普宁县
在PLC控制系统中，电源占有极重要的地位。电网干扰串入PLC控制系统主要通过PLC系统的供电电源（如电源、I/O电源等）、变送器供电电源和与PLC系统具有直接电气连接的仪表供电电源等耦合进入的。现在，对于PLC系统供电的电源，一般都采用隔离性能较好电源，而对于变送器供电的电源和PLC系统有直接电气连接的仪表的供电电源，并没受到足够的重视，虽然采取了一定的隔离措施，但普遍还不够，主要是使用的隔离变压器分布参数大，抑制干扰能力差，经电源耦合而串入共模干扰、差模干扰。所以，对于变送器和共用信号仪表供电应选择分布电容小、抑制带大（如采用多次隔离和屏蔽及漏感技术）的配电器，以减少PLC系统的干扰。
位保证电网馈点不中断，可采用在线式不间断供电电源（UPS）供电，提高供电的安全可靠性。并且UPS还具有较强的干扰隔离性能，是一种PLC控制系统的理想电源。
2电缆选择的敖设
为了减少动力电缆辐射电磁干扰，尤其是变频装置馈电电缆。笔者在某工程中，采用了铜带铠装屏蔽电力电缆，从而降低了动力线生产的电磁干扰，该工程投产后取得了满意的效果。
上世纪60年代后期，根据当时汽车市场需求和计算技术的发展，在美国麻萨诸塞州Bedford的Bedford Associates,向美国汽车制造业提议开发一种Modular Digital Controller（MODICON）取代继电控制盘。其它一些公司也建议以计算机为基础的方案。其核心思想是采用软件编程方法代替继电控制的硬接线方式，并备有生产现场大量使用的输入传感器和输出执行器的接口，以便于进行大规模生产线的流程控制。这就是以后被称为Programmable Logic Controller的由来。MODICON 084是世界上种投入商业生产的PLC。
0年代是PLC崛起，首先在汽车工业获得大量应用，在其它产业部门也开始应用的时期。80年代是它走向成熟，全面采用微电子及微处理器技术；大量推广应用，并奠定其在工业控制中不可动摇地位的时期。在此阶段PLC销售始终以两位数百分点的速度增长，前六年的增长率超过35%，后四年稳定发展，年增长率约12%。90年代又开始了它的第三个发展时期。随着PLC的IEC 61131的正式颁布，推动了PLC在技术上发动新的突破：在系统体系结构上，从传统的单机向多和分布式及远程控制系统发展；在编程语言上，文本化和图形化的语言多样性，创造了更具表达控制要求、文字处理、通信能力的编程环境。
从应用范围和应用水平上，除了继续发展机械加工自动生产线的控制系统外，则是发展以PLC为基础的DCS系统、监控和数据采SCADA系统、柔性制造系统（FMS）、安全联锁保护（ESD）系统、运动控制系统等，全方位地产提高PLC的应用范围和水平。
进入90年代后期，由于用户对开放性的强烈要求和压力，由于信息技术的大力推动，PLC如果还停留在原有的专用而又封闭的系统概念上，它将坐以待毙。于是PLC进入了其发展的第四阶段。其特征是：
SMIB-UGSM-Interbus-S User Guide
SM-INTERBUSInterbus-S Solutions Module
SM-KEYPADLED Keypad 7 digit LED data display Configured for Unidrive SP
SM-KEYPAD PLUS LCD Keypad back-lit dual language on-screen help remote mountable
SMPB-UG SM-Profibus User Guide
SM-PELVPELV Solutions Module - Isolated I/O to NAMUR NE37 specification for chemical industry applications
SM-PELV PELV Solutions Module - Isolated I/O to NAMUR NE37 specification for chemical industry applications
SM-PROFIBUS Profibus-DP Solutions Module - Fieldbus Option Only
SM-PROFIBUSProfibus-DP Solutions Module - Fieldbus Option Only
SM-RESOLVERResolver Solutions Module providing a resolver feedback port w/simulated encoder output
SM-SERCOSSERCOS Solutions Module
SM-SLMSLM Solutions Module
SMUE-UGSM-Uni Encoder User Guide
SM-UNI ENCODERUniversal Encoder Plus Solutions Module provides an additional increamental or Absolute encoder feedback port and simulated encoder output.
SM-WinderSM Speed and Torque based Centerwind Preprogrammed Option Module
SNCDD-001.5mso-spacerun: yes> Sync in/out cable 7 Pin Mini-DIN connector on one end and an 8 Pin Mini -DIN connector on the other 1.5 ft Length (FM3/4 to FM3/4)
SP1201-LCDUnidrive SP with LCD Keypad 230Vac Max Cont Output Current (hp): Normal Duty - 5.2A (1.5hp) Heavy Duty - 4.3A (1hp)
SP1201-LEDUnidrive SP with LED Keypad 230Vac Max Cont Output Current (hp): Normal Duty - 5.2A (1.5hp) Heavy Duty - 4.3A (1hp)
SP1201-NKPUnidrive SP without Keypad 230Vac Max Cont Output Current (hp): Normal Duty - 5.2A (1.5hp) Heavy Duty - 4.3A (1hp)
SP1202-LCDUnidrive SP with LCD Keypad 230Vac Max Cont Output Current (hp): Normal Duty - 6.8A (2hp) Heavy Duty - 5.8A (1.5hp)
SP1202-LEDUnidrive SP with LED Keypad 230Vac Max Cont Output Current (hp): Normal Duty - 6.8A (2hp) Heavy Duty - 5.8A (1.5hp)
SP1202-NKPUnidrive SP without Keypad 230Vac Max Cont Output Current (hp): Normal Duty - 6.8A (2hp) Heavy Duty - 5.8A (1.5hp)
SP1203-LCDUnidrive SP with LCD Keypad 230Vac Max Cont Output Current (hp): Normal Duty - 9.6A (3hp) Heavy Duty - 7.5A (2hp)
SP1203-LEDUnidrive SP with LED Keypad 230Vac Max Cont Output Current (hp): Normal Duty - 9.6A (3hp) Heavy Duty - 7.5A (2hp)
SP1203-NKPUnidrive SP without Keypad 230Vac Max Cont Output Current (hp): Normal Duty - 9.6A (3hp) Heavy Duty - 7.5A (2hp)
SP1204-LCDUnidrive SP with LCD Keypad 230Vac Max Cont Output Current (hp): Normal Duty - 11A (3hp) Heavy Duty - 10.6A (3hp)
SP1204-LEDUnidrive SP with LED Keypad 230Vac Max Cont Output Current (hp): Normal Duty - 11A (3hp) Heavy Duty - 10.6A (3hp)
SP1204-NKPUnidrive SP without Keypad 230Vac Max Cont Output Current (hp): Normal Duty - 11A (3hp) Heavy Duty - 10.6A (3hp)
SP1401-LCDUnidrive SP with LCD Keypad 460Vac Max Cont Output Current (hp): Normal Duty - 2.8A (1.5hp) Heavy Duty - 2.1A (1hp)
SP1401-LEDUnidrive SP with LED Keypad 460Vac Max Cont Output Current (hp): Normal Duty - 2.8A (1.5hp) Heavy Duty - 2.1A (1hp)
SP1401-NKPUnidrive SP without Keypad 460Vac Max Cont Output Current (hp): Normal Duty - 2.8A (1.5hp) Heavy Duty - 2.1A (1hp)
SP1402-LCDUnidrive SP with LCD Keypad 460Vac Max Cont Output Current (hp): Normal Duty - 3.8A (2hp) Heavy Duty - 3.0A (2hp)
SP1402-LEDUnidrive SP with LED Keypad 460Vac Max Cont Output Current (hp): Normal Duty - 3.8A (2hp) Heavy Duty - 3.0A (2hp)
SP1402-NKPUnidrive SP without Keypad 460Vac Max Cont Output Current (hp): Normal Duty - 3.8A (2hp) Heavy Duty - 3.0A (2hp)
SP1403-LCDUnidrive SP with LCD Keypad 460Vac Max Cont Output Current (hp): Normal Duty - 5.0A (3hp) Heavy Duty - 4.2A (3hp)
SP1403-LEDUnidrive SP with LED Keypad 460Vac Max Cont Output Current (hp): Normal Duty - 5.0A (3hp) Heavy Duty - 4.2A (3hp)
SP1403-NKPUnidrive SP without Keypad 460Vac Max Cont Output Current (hp): Normal Duty - 5.0A (3hp) Heavy Duty - 4.2A (3hp)
SP1404-LCDUnidrive SP with LCD Keypad 460Vac Max Cont Output Current (hp): Normal Duty - 6.9A (5hp) Heavy Duty - 5.8A (3hp)
SP1404-LEDUnidrive SP with LED Keypad 460Vac Max Cont Output Current (hp): Normal Duty - 6.9A (5hp) Heavy Duty - 5.8A (3hp)
SP1404-NKPUnidrive SP without Keypad 460Vac Max Cont Output Current (hp): Normal Duty - 6.9A (5hp) Heavy Duty - 5.8A (3hp)
SP1405-LCDUnidrive SP with LCD Keypad 460Vac Max Cont Output Current (hp): Normal Duty - 8.8A (5hp) Heavy Duty - 7.6A (5hp)
SP1405-LEDUnidrive SP with LED Keypad 460Vac Max Cont Output Current (hp): Normal Duty - 8.8A (5hp) Heavy Duty - 7.6A (5hp)
SP1405-NKPUnidrive SP without Keypad 460Vac Max Cont Output Current (hp): Normal Duty - 8.8A (5hp) Heavy Duty - 7.6A (5hp)
SP1406-LCDUnidrive SP with LCD Keypad 460Vac Max Cont Output Current (hp): Normal Duty - 11A (7.5hp) Heavy Duty - 9.5A (5hp)