User`s guide

4 External Mode
4-20
Limitations
In general, you cannot change a parameter if doing so results in a change in the
structure of the model. For example, you cannot change:
• The number of states, inputs, or outputs of any block
• The sample time or the number of sample times
• The integration algorithm for continuous systems
• The name of the model or of any block
• The parameters to the Fcn block
If you cause any of these changes to the block diagram, then you must rebuild
the program with newly generated code.
However, parameters in transfer function and state space representation
blocks can be changed in specific ways:
• The parameters (numerator and denominator polynomials) for the Transfer
Fcn (continuous and discrete) and Discrete Filter blocks can be changed (as
long as the number of states does not change).
• Zero entries in the State Space and Zero Pole (both continuous and discrete)
blocks in the user-specified or computed parameters (i.e., the A, B, C, and D
matrices obtained by a zero-pole to state-space transformation) cannot be
changed once external simulation is started.
• In the State Space blocks, if you specify the matrices in the controllable
canonical realization, then all changes to the A, B, C, D matrices that
preserve this realization and the dimensions of the matrices are allowed. For
a discussion of controllable canonical realizations, see Linear Systems
Theory by C.T. Chen.
TCP Implementation
The Real-Time Workshop provides code to implement both the client and
server side based on TCP. You can use socket-based external mode
implementation provided by the Real-Time Workshop with the generated code,
provided that your target system has an external mode server. For example,
the Tornado environment and generic real-time targets contain an external
server.