可编程控制器（programmable logical controller，简称PLC）已经越来越多地应用于工业控制系统中，并且在自动控制系统中起着重要的作用。所以，对PLC的正确选择是重要的。
面对众多生产厂家的各种类型PLC，它们各有优缺点，能够满足用户的各种需求，但在形态、组成、功能、网络、编程等方面各不相容，没有一个统一的标准，无法进行横向比较。下面提出在自动控制系统设计中对PLC选型的一些看法，可以在挑选PLC时作为参考。
可以通过以下几方面的比较，挑选到适合的产品。
这一点尤为重要。在自动控制系统设计之初，就应该对控制点数（数字量及模拟量）有一个准确的统计，这往往是选择PLC的首要条件，一般选择比控制点数多10%~30%的PLC。这有几方面的考虑：
1、可以弥补设计过程中遗漏的点；
2、能够保证在运行过程中个别点有故障时，可以有替代点；
3、将来增加点数的需要。
工作环境是PLC工作的硬性指标。自控系统将人们从繁忙的工作和恶劣的环境中解脱出来，就要求自控系统能够适应复杂的环境，诸如温度、湿度、噪音、信号屏蔽、工作电压等，各款PLC不尽相同。一定要选择适应实际工作环境的产品。
ALLEN BRADLEY 150-A54NCD 150A54NCD
ALLEN BRADLEY 1400-PD52A 1400PD52A
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ALLEN BRADLEY 1336-B020-AA-EN-HAS1-L6 DRIVE 20HP 460VAC/60HZ 3PHASE * NO BOX*
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ALLEN BRADLEY 1326AS-B440G-21 SERIES A **
ALLEN BRADLEY 1326AB-C3E-11-2287B 1326ABC3E112287B
ALLEN BRADLEY 1326AB-B740C-21-L 1326ABB740C21L
ALLEN BRADLEY 1326AB-B430G-M2K4L * IN BOX*
ALLEN BRADLEY 1326AB-B420H-M2L 1326ABB420HM2L
ALLEN BRADLEY 100-B400NA3 100B400NA3
ABB Memory 86-192K Allen Bradley Stromberg 200039
8520-ASM3 ALLEN BRADLEY ELECTRONIC CIRCUIT BOARD
8500-B1D-K1B ALLEN BRADLEY SERVO MOTORS REMANUFACTURED
6180-EIKEGZDBEZZ ALLEN BRADLEY MONITORS CRT REMANUFACTURED
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**SEALED**Allen Bradley 1770-KFC15/1770KFC15 **** **WARRANTY**
* * Allen Bradley 2711-K9C3 PanelView 900 Color Operator Interface w/ DH-485