DI810 3BSE008508R1 ABB

PLC has formed micro,small,medium,large and giant PLC in the 1990s.According to the number of I/O points,it can be divided into:

lMicro PLC:32I/O

lSmall PLC:256I/O

lMedium PLC:1024I/O

lLarge PLC:4096I/O

lGiant PLC:8195I/O

In recent years,there are large-scale systems that support 300 loops and 65,000 I/O points in a single machine,corresponding to medium-sized PLCs and above,all of which use 16-bit to 32-bit CPUs.Micro and small PLCs originally used 8-bit CPUs.Now,according to the requirements of communication and other aspects,some are also Use a 16-bit to 32-bit CPU instead.Due to I/O

PLC sales below 64 points account for 47%of the entire PLC,and 64 points to 256 points account for 31%,which together account for 78%of the entire PLC sales,so more research should be done on micro and small PLCs.

PLC在90年代已经形成微、小、中、大、巨型多种PLC。按I/O点数分，可分为:

l微型PLC:32I/O

l小型PLC:256I/O

l中型PLC:1024I/O

l大型PLC:4096I/O

l巨型PLC:8195I/O

近年来有单机支持300回路和65000点I/O的大型系统对应中型PLC以上，均采用16位~32位CPU，微、小型PLC原采用8位CPU，现在根据通讯等方面要求，有的也改用16位~32位CPU。由于I/O

64点以下PLC销售额占整个PLC的47%，64点~256点的占31%，合计位整个PLC销售额的78%，所以对微、小型PLC应多加研究。