可编程控制器PLC的应用绝大部分都是通过编写梯形图的方式实现程序控制的，但对于智能低压开关系统来讲，其分、断的控制往往要求由主控操作室远程控制来完成。按传统的方法，主控室要对某一个开关柜进行操作，须先发一个控制命令，PLC接收到该控制命令后，再由PLC程序执行该命令，该段程序必须用梯形图或逻辑指令编程，当开关柜数目巨大或要求多路设备同时控制时，PLC的程序编写就比较复杂，尤其是采用脉冲型输出控制而不是用电平保持型控制时更是如此。因为开关柜的分、合控制须两路继电器输出分别控制“分闸”和“合闸”，而不是由单路继电器保持输出控制，使继电器输出与开关柜分合一致。考虑这些因素，本文采用串行通讯实现PLC的控制，PLC本机无须任何梯形图或逻辑指令，这样不仅实现简单而且方便可靠。
PLC most of the preparation ladder through the realization of the program control, But for intelligent systems in terms of low-voltage switches, broken, broken by the control often requires the control room to operate remote control to complete. By the traditional method, a main control room to carry out a switchboard operation, the subject of a control order, PLC received the control orders, by the PLC program implementation of the order, The above procedures must be used or ladder logic programming instructions, when the huge number of switchgear or request multiple simultaneous control of equipment, PLC programming more complicated, particularly by using pulse-output control rather than power to maintain peace-control centers. Switchboard because the hours cooperation to control two sep (2006-12-31, WORD, 37KB, 下载40次)