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小型可编程序控制器(下称PC)在使用中普遍存在“内存”有余而嫌I/O点数不足的问题。目前PC的市场价格基本上仍与I/O点数成比例。即便选用专门的扩展单元,也需增加主机费用的2/3。为此,我们从充分利用PC的内存出发,用组合编码法扩展I/O点数。方法简单可行,经济实用。1.输入点数扩展设PC的现有输入点数为n,将它分成点数分别为P和Q的两组(n=P+Q)。若两组中各取一点进行组合,则可有P×Q种不同的组合。如果把输入信号同时向每组各一点进行输入,则允许有p×Q个输入信号与其对应。当P=Q=n/2时,PC的n个输入端子允许相应的输入信号数最多,为(n/2)~2个。PC输入端子数和采用组合编码方式输入后允许相
Small programmable logic controller (hereinafter referred to as PC) in the widespread use of “memory” but I / O lack of points. At present, the market price of PCs is still basically proportional to the number of I / O points. Even if the use of specialized expansion unit, also need to increase the cost of host 2/3. To this end, we take full advantage of the memory of the PC, the combination of coding method to expand I / O points. The method is simple and feasible, economical and practical. 1. Enter Number of Points Extension Set the PC’s existing input points to n and divide it into two groups of points P and Q (n = P + Q). If two points in each group are combined, there may be P × Q different combinations. If input signals are simultaneously input to each group, p × Q input signals are allowed to correspond to them. When P = Q = n / 2, the PC’s n input terminals allow the corresponding maximum number of input signals, from (n / 2) ~ 2. The number of PC input terminals and the use of combined encoding input allows the phase