第章可编程序控制器的基础知识yy.ppt

KT is time relay, KM1 and KM2 are two contactors control electrical machines M1, M2 running.SB1 is startup button, SB2 is stop button with the control function as follows; press SB1, M1 start running, after 10 seconds, M2 start running; press SB2, M1,M2 stop running at the same time. 梯形图中继电器线圈是广义的 ，除了输出继电器、辅助继电器线圈外，还包括定时器、计数器、移位寄存器以及各种算术运算等。 Relay loop in trapezoid diagram consists timer, counter, shift register, various arithmetic operation as well as output relay and assistant relay loops. 梯形图的母线中无电流。No electricity in generatrix . 梯形图中只出现输入继电器的触点，而不出现输入继电器的线圈。输入继电器的触点表示相应的输入信号。 Only input relay spot appears in trapezoid diagram and the loop does not appear. The input spot denotes corresponding input signal. 输出继电器供PLC作输出控制用。 Output relay work as PLC output controller. PLC运行的顺序是“从左到右，从上到下”，逐一处理，扫描方式工作 PLC running sequence is “from left to right, from up to down”, dealing one by one, scanning manner working. 用户程序执行时，输入触点和输出线圈的状态是从I/O映象寄存器中读取的，不是执行时现场开关的实际状态。梯形图中前面程序执行的结果马上可以被后面的程序执行所利用。 As user’s program running, the state of input spot and output loop is read in from I/O mapping register rather than the actual state of local switch as executing. Results of former program in trapezoid can be used by latter program at once. §1-4-2 语句表 sentence table 是一种与汇编语言类似的助记符编程表达式 A mnemonic symbol program expression that is similar to assembly language PLC的语句：操作码 + 操作数 操作码：用来指定要执行的功能，告诉CPU该进行什么操作。 操作数：包含为执行该操作所必须的信息。告诉CPU用什么地方的数据来执行此操作。 operand：include the necessary information for operation. inform CPU the address of the data for executing the operation PLC sentence：operation code+ operand Operation code: specify function to be executed, notify CPU what operation to do 操作数的分配原则 为了让CPU区别不同的编程元件，每个独立的元件应指定一个互不重复的地址。 To make CPU differentiating various components, each of independent component should specify address that is not repeated to each other. 所指定的地址必须在该型机器允许的范围之内。超出机器允许的操作参数，PLC不响应，并以出错处理。 The specified address should be within allowable range. If