# ReleaseNotes.Version_2_1

## Information

This is a major change with respect to previous versions of the Modelica Standard Library, because many new libraries and components are included and because the input/output blocks (Modelica.Blocks) have been considerably simplified:

- An input/output connector is defined without a hierarchy (this is possible due to new features of the Modelica language). For example, the input signal of a block "FirstOrder" was previously accessed as "FirstOrder.inPort.signal[1]". Now it is accessed as "FirstOrder.u". This simplifies the understanding and usage especially for beginners.
- De-vectorized the Modelica.Blocks library. All blocks in the Modelica.Blocks library are now scalar blocks. As a result, the parameters of the Blocks are scalars and no vectors any more. For example, a parameter "amplitude" that might had a value of "{1}" previously, has now a value of "1". This simplifies the understanding and usage especially for beginners.
  If a vector of blocks is needed, this can be easily accomplished by adding a dimension to the instance. For example "Constant const[3](k={1,2,3}" defines three Constant blocks. An additional advantage of the new approach is that the implementation of Modelica.Blocks is much simpler and is easier to understand.

The discussed changes of Modelica.Blocks are not backward compatible. A script to automatically convert models to this new version is provided. There might be rare cases, where this script does not convert. In this case models have to be manually converted. In any case you should make a back-up copy of your model before automatic conversion is performed.

The following new libraries have been added:

Modelica.Electrical.Digital | Digital electrical components based on 2-,3-,4-, and 9-valued logic according to the VHDL standard
Modelica.Electrical.Machines | Asynchronous, synchronous and DC motor and generator models
Modelica.Math.Matrices | Functions operating on matrices such as solve() (A*x=b), leastSquares(), norm(), LU(), QR(), eigenValues(), singularValues(), exp(), ...
Modelica.StateGraph | Modeling of discrete event and reactive systems in a convenient way using hierarchical state machines and Modelica as action language. It is based on JGrafchart and Grafcet and has a similar modeling power as StateCharts. It avoids deficiencies of usually used action languages. This library makes the ModelicaAdditions.PetriNets library obsolete.
Modelica.Utilities.Files | Functions to operate on files and directories (copy, move, remove files etc.)
Modelica.Utilities.Streams | Read from files and write to files (print, readLine, readFile, error, ...)
Modelica.Utilities.Strings | Operations on strings (substring, find, replace, sort, scanToken, ...)
Modelica.Utilities.System | Get/set current directory, get/set environment variable, execute shell command, etc.

The following existing libraries outside of the Modelica standard library have been improved and added as new libraries (models using the previous libraries are automatically converted to the new sublibraries inside package Modelica):

Modelica.Blocks.Discrete | Discrete input/output blocks with fixed sample period (from ModelicaAdditions.Blocks.Discrete)
Modelica.Blocks.Logical | Logical components with Boolean input and output signals (from ModelicaAdditions.Blocks.Logical)
Modelica.Blocks.Nonlinear | Discontinuous or non-differentiable algebraic control blocks such as variable limiter, fixed, variable and Pade delay etc. (from ModelicaAdditions.Blocks.Nonlinear)
Modelica.Blocks.Routing | Blocks to combine and extract signals, such as multiplexer (from ModelicaAdditions.Blocks.Multiplexer)
Modelica.Blocks.Tables | One and two-dimensional interpolation in tables. CombiTimeTable is available in Modelica.Blocks.Sources (from ModelicaAdditions.Tables)
Modelica.Mechanics.MultiBody | Components to model the movement of 3-dimensional mechanical systems. Contains body, joint, force and sensor components, analytic handling of kinematic loops, force elements with mass, series/parallel connection of 3D force elements etc. (from MultiBody 1.0 where the new signal connectors are used; makes the ModelicaAdditions.MultiBody library obsolete)

As a result, the ModelicaAdditions library is obsolete, because all components are either included in the Modelica library or are replaced by much more powerful libraries (MultiBody, StateGraph).

The following new components have been added to existing libraries.

Modelica.Blocks.Logical.
Pre | y = pre(u): Breaks algebraic loops by an infinitesimal small time delay (event iteration continues until u = pre(u))
Edge | y = edge(u): Output y is true, if the input u has a rising edge
FallingEdge | y = edge(not u): Output y is true, if the input u has a falling edge
Change | y = change(u): Output y is true, if the input u has a rising or falling edge
GreaterEqual | Output y is true, if input u1 is greater or equal than input u2
Less | Output y is true, if input u1 is less than input u2
LessEqual | Output y is true, if input u1 is less or equal than input u2
Timer | Timer measuring the time from the time instant where the Boolean input became true
Modelica.Blocks.Math.
BooleanToReal | Convert Boolean to Real signal
BooleanToInteger | Convert Boolean to Integer signal
RealToBoolean | Convert Real to Boolean signal
IntegerToBoolean | Convert Integer to Boolean signal
Modelica.Blocks.Sources.
RealExpression | Set output signal to a time varying Real expression
IntegerExpression | Set output signal to a time varying Integer expression
BooleanExpression | Set output signal to a time varying Boolean expression
BooleanTable | Generate a Boolean output signal based on a vector of time instants
Modelica.Mechanics.MultiBody.
Frames.from_T2 | Return orientation object R from transformation matrix T and its derivative der(T)
Modelica.Mechanics.Rotational.
LinearSpeedDependentTorque | Linear dependency of torque versus speed (acts as load torque)
QuadraticSpeedDependentTorque | Quadratic dependency of torque versus speed (acts as load torque)
ConstantTorque | Constant torque, not dependent on speed (acts as load torque)
ConstantSpeed | Constant speed, not dependent on torque (acts as load torque)
TorqueStep | Constant torque, not dependent on speed (acts as load torque)

The following bugs have been corrected:

Modelica.Mechanics.MultiBody.Forces.
LineForceWithMass Spring | If mass of the line force or spring component is not zero, the mass was (implicitly) treated as "mass*mass" instead of as "mass"
Modelica.Mechanics.Rotational.
Speed | If parameter exact=false, the filter was wrong (position was filtered and not the speed input signal)

Other changes:

- All connectors are now smaller in the diagram layer. This gives a nicer layout when connectors and components are used together in a diagram
- Default instance names are defined for all connectors, according to a new annotation introduced in Modelica 2.1. For example, when dragging connector "Flange_a" from the Rotational library to the diagram layer, the default connector instance name is "flange_a" and not "Flange_a1".
- The Modelica.Mechanics.Rotational connectors are changed from a square to a circle
- The Modelica.Mechanics.Translational connectors are changed from a green to a dark green color in order that connection lines can be better seen, especially when printed.
- The Modelica.Blocks connectors for Real signals are changed from blue to dark blue in order to distinguish them from electrical signals.

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