Triconex 3501E应用于电工电气机械设备卡件模块

Triconex 3501E应用于电工电气机械设备卡件模块

Triconex 3501E应用于电工电气机械设备卡件模块

1、输入采样阶段在输入采样阶段

PLC以扫描方式依次地读入所有输入状态和数据，并将它们存入I/O映象区中的相应得单元内。输入采样结束后，转入用户程序执行和输出刷新阶段。在这两个阶段中，即使输入状态和数据发生变化，V/O映象区中的相应单元的状态和数据也不会改变。因此，如果输入是脉冲信号，则该脉冲信号的宽度大于一个扫描周期，才能在任何情况下，该输入均能被读入。

2、用户程序执行阶段

在用户程序执行阶段，PLC总是按由上而下的顺序依次地扫描用户程序(梯形图)。在扫描每一条梯形图时，又总是先扫描梯形图左边的由各触点构成的控制线路，并按先左后右、先上后下的顺序对由触点构成的控制线路进行逻辑运算，然后根据逻辑运算的结果，刷新该逻辑线圈在系统RAM存储区中对应位的状态;或者刷新该输出线圈在/O映象区中对应位的状态;或者确定是否要执行该梯形图所规定的特殊功能指令。

即，在用户程序执行过程中，只有输入点在I/O映象区内的状态和数据不会发生变化，而其他输出点和软设备在/O映象区或系统RAM存储区内的状态和数据都有可能发生变化，而且排在上面的梯形图，其程序执行结果会对排在下面的凡是用到这些钱圈或数据的梯形图起作用相反，排在下面的梯形图，其被刷新的逻辑线圈的状态或数据只能到下一个扫描周期才能对排在其上面的程序起作用。在程序执行的过程中如果使用立即/O指令则可以直接存取I/O点。即使用/O指令的话，输入过程影像寄存器的值不会被更新，程序直接从I/O模块取值，输出过程影像寄存器会被立即更新，这跟立即输入有些区别。

3、输出刷新阶段

当扫描用户程序结束后，PLC就进入输出刷新阶段。在此期间，CPU按照/O映象区内对应的状态和数据刷新所有的输出锁存电路，再经输出电路驱动相应的外设。这时，才是PLC的真正输出。

Triconex 3501E应用于电工电气机械设备卡件模块

1, input sampling stage in the input sampling stage

The PLC successively reads all input status and data in a scanning manner and stores them in the corresponding cell in the I/O map area. After the end of the input sampling, the user program execution and output refresh phase. In these two stages, even if the input state and data change, the state and data of the corresponding cell in the V/O map area will not change. Therefore, if the input is a pulse signal, the width of the pulse signal is greater than one scan cycle, so that the input can be read in any case.

2. User program execution stage

In the execution phase of the user program, the PLC always scans the user program in sequence from top to bottom (ladder diagram). When scanning each ladder diagram, it always scans the control line composed of each contact on the left side of the ladder diagram first, and carries out logical operations on the control line composed of contacts in the order of first left and then right, first up and then down, and then refreshes the status of the corresponding bit of the logic coil in the system RAM storage area according to the results of logical operations; Or refresh the state of the corresponding bit of the output coil in the /O map area; Or determine whether to execute the special function instructions specified in the ladder diagram.

That is, during the execution of the user program, only the status and data of the input point in the I/O image area will not change, while the status and data of other output points and software devices in the /O image area or the system RAM storage area are likely to change, and the status and data are listed above. The results of the program execution will have an effect on any ladder diagram below that uses these loops or data. In contrast, in the ladder diagram below, the status or data of the logic coil that is refreshed will have an effect on the program above it only until the next scan cycle. I/O points can be accessed directly if immediate /O instructions are used during program execution. Even if the /O instruction is used, the value of the input process image register is not updated, the program is directly taken from the I/O module, and the output process image register is updated immediately, which is somewhat different from the immediate input.

3. Output refresh phase

When the scanning user program is finished, the PLC enters the output refresh stage. During this period, the CPU refreshes all output latches according to the corresponding state and data in the /O map area, and then drives the corresponding peripherals through the output circuit. At this time, is the real output of PLC.