The xTIMEcomposer simulator can optionally generate a VCD (value change dump) trace file which describes external and/or internal simulation state. This file can then be viewed in the VCD viewer built in to xTIMEcomposer Studio, or in an 3rd party VCD viewer such as GTKWave. This mechanism is typically used to visualize the transitions on the ports/pins（典型地被用于观察ports/pins的变化）, although you can also use it to examine internal machine state such as the instructions/functions executed（也可用于观察指令函数的状态机） and the state of other machine resources such as channels, clock blocks（或者诸如channel,clock block之类的资源状态）.
From within xTIMEcomposer Studio, the VCD tracing can be enabled using:
Run-> Run Configurations -> Simulator -> Signal Tracing -> Enable signal tracing
->Check thisbox, (Box:Enable signal tracing)
->then clickthe ADD button situated within the Trace Tile Options group.
->Check the portsbox.
When the projectis run, a .vcd file is produced and added at the top level of the releventproject directory. Double-click on this file to load it into the built-in VCDviewer.
->Double-clickon XS1_PORT_1A in the signals view to import the associated signals into theWaves view. Click the zoom fit button located in the Waves view toolbar toexamine the activity on the port.
问题：VCD出错，不能生成.vcd文件，不知为什么？
->发现在run configurations->XScope->Mode被设为Real-Time Mode，改设成Disable后，VCD正常工作。如果没有disable XScope Mode，那么就会出现下面的XScopePlugin Error:
