TwinCAT 3 Library及功能块操作说明: IF条件句的对象实例怎么释放比较好?TwinCAT 3运用中发现如果把功能块实例放在IF语句中运行，运行时当IF条件不满足时，功能块之前得有些状态还在保持。 | 倍福虚拟学院

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1. 自定义库添加说明文档restructured Text
2. 如何查看，设置和固定TwinCAT 3中的库文件版本？打开他人程序PLC References下库缺失（库感叹号）怎么处理？
3. 如何在声明时，对功能块引脚进行初始化参数赋值？
4. 请问Function Block和Function使用有什么区别？
5. 在ST语言中和梯形图中分别如何添加功能块？
6. 添加库文件报错，提示it is being used by another process
7. Real浮点数计算值为0是什么原因？
8. IF条件句的对象实例怎么释放比较好?TwinCAT 3运用中发现如果把功能块实例放在IF语句中运行，运行时当IF条件不满足时，功能块之前得有些状态还在保持。
9. 带占空比的方波输出是哪个功能块，在哪个库里？
10. TwinCAT 3中的库文件SysFile和SysDir是干什么的？

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TwinCAT 3 Library及功能块操作说明

8. IF条件句的对象实例怎么释放比较好?TwinCAT 3运用中发现如果把功能块实例放在IF语句中运行，运行时当IF条件不满足时，功能块之前得有些状态还在保持。

答：

IF不满足，只是功能块不执行，值保持是正常现象。可以对功能块清零，再加一个Elsif做清零就行。

2017.12.18 冯建鹏编辑