Modelica编码标准/ Modelica语句

Question

欢迎大家，

2020年新年快乐

我正在64位windows 7系统上使用Openmodelica 1.14发行版。

我在OMSimulator中的“时间”声明遇到了一些麻烦。在寻找解决方案时，我遇到了一个Openmodelica中的封闭票#2664。我仍然可以在Openmodelica的当前版本中看到报告的问题。

我正在包括有关的文件，票# 2664。

model SimpleTest "just a simple model - Compilation etc."
  Modelica.Blocks.Interfaces.IntegerInput u annotation(Placement(visible = true, transformation(origin = {-100, 40}, extent = {{-10, -10}, {10, 10}}, rotation = 0), iconTransformation(origin = {-80, 40}, extent = {{-10, -10}, {10, 10}}, rotation = 0)));
  Modelica.Blocks.Interfaces.IntegerOutput y annotation(Placement(visible = true, transformation(origin = {100, 20}, extent = {{-10, -10}, {10, 10}}, rotation = 0), iconTransformation(origin = {100, 20}, extent = {{-10, -10}, {10, 10}}, rotation = 0)));
algorithm
  when change(u) then
    y := y + 2;
  end when;
  annotation(Icon(coordinateSystem(extent = {{-100, -100}, {100, 100}}, preserveAspectRatio = true, initialScale = 0.1, grid = {2, 2})), Diagram(coordinateSystem(extent = {{-100, -100}, {100, 100}}, preserveAspectRatio = true, initialScale = 0.1, grid = {2, 2}), graphics = {Rectangle(origin = {-6.15, 2.93}, fillColor = {0, 133, 199}, fillPattern = FillPattern.HorizontalCylinder, extent = {{-77.89, 83.75}, {88.14, -92.53}})}));
end SimpleTest;

SimpleTest.mo是否符合Modelica标准？

在编译SimpleTest.mo时，它抛出翻译警告

Assuming fixed start value for the following 1 variables:
         y:DISCRETE(flow=false fixed = false ) SimpleTest type: Integer

如何避免此错误？

Answer 1

这只是一个警告。当您定义这样的离散变量时，它依赖于它在一个时间条件中的前一个值，它必须有一个固定的开始值。仅仅提供一个开始值是编译器的一个猜测值，当您修复它时，您会告诉编译器它必须使用这个值进行初始化。

如果不提供开始值，则将其设置为零，如果不修复该值，编译器将自动修复它(导致警告)。

简单的例子：

Integer y(start=0, fixed=true);

应用于您的模型：

model SimpleTest "just a simple model - Compilation etc."
  Modelica.Blocks.Interfaces.IntegerInput u annotation(Placement(visible = true, transformation(origin = {-100, 40}, extent = {{-10, -10}, {10, 10}}, rotation = 0), iconTransformation(origin = {-80, 40}, extent = {{-10, -10}, {10, 10}}, rotation = 0)));
  Modelica.Blocks.Interfaces.IntegerOutput y(start=0, fixed=true) annotation(Placement(visible = true, transformation(origin = {100, 20}, extent = {{-10, -10}, {10, 10}}, rotation = 0), iconTransformation(origin = {100, 20}, extent = {{-10, -10}, {10, 10}}, rotation = 0)));
algorithm
  when change(u) then
    y := y + 2;
  end when;
  annotation(Icon(coordinateSystem(extent = {{-100, -100}, {100, 100}}, preserveAspectRatio = true, initialScale = 0.1, grid = {2, 2})), Diagram(coordinateSystem(extent = {{-100, -100}, {100, 100}}, preserveAspectRatio = true, initialScale = 0.1, grid = {2, 2}), graphics = {Rectangle(origin = {-6.15, 2.93}, fillColor = {0, 133, 199}, fillPattern = FillPattern.HorizontalCylinder, extent = {{-77.89, 83.75}, {88.14, -92.53}})}));
end SimpleTest;