User`s guide

1 Getting Started
1-12
System Concepts
A more detailed understanding of Real-Time Workshop and the Real-Time
Windows Target can help you when creating and running your real-time
applications.
This section includes the following topics:
• “Simulink External Mode” on page 1-12
• “Data Buffers and Transferring Data” on page 1-13
Simulink External Mode
External mode requires a communications interface to pass parameters
external to Simulink, and on the receiving end, the same communications
protocol must be used to accept new parameter values and insert them in the
proper memory locations for use by the real-time application. In some
Real-Time Workshop targets such as Tornado/VME targets, the
communications interface uses TCP/IP protocol. In the case of the Real-Time
Windows Target, the host computer also serves as the target computer.
Therefore, only a virtual device driver is needed to exchange parameters
between MATLAB and Simulink memory space and memory that is accessible
by the real-time application.
Signal acquisition — You can capture and display signals from your real-time
application while it is running. Signal data is retrieved from the real-time
application and displayed in the same Simulink Scope blocks you used for
simulating your model.
Parameter tuning — You can change parameters in your Simulink block
diagram and have the new parameters passed automatically to the real-time
application. Simulink external mode changes parameters in your real-time
application while it is running in real time.
As a user of the Real-Time Windows Target, you will find that the
requirements for setup are minimal. You start by enabling external mode. You
then choose the RTW system target file from the
Simulation Parameters
dialog
Real-Time Workshop tab. The MEX-file interface is automatically
selected when you choose the target file. Then, after you have built the
real-time application, you are ready for external mode operation.