User`s guide

General xPC Target™ Troubleshooting
• Spurious CPU overloads — Commonly caused by factors outside of the
model desig n. These overloads are most likely caused by one of the
following:
- BIOS settings (enabled Advanced Power Management, USB ports in
the target PC BIOS, or Plug and Play (PnP) (see “Target PC BIOS” on
page 15-24)
- System management interrupts (SMIs)
Dealing with Small Model Sample Times
If the model has too small a sample time, a CPU overload can occur. This
error indicates that to run the target application, executing one step of the
model requires more time than the sample time for the model (
Fixed step
size
property) allows.
When this error occurs, the target object property
CPUoverload changes from
none to detected. To correct the issue, perform one of the f ollowing:
• Change the model
Fixed step size property to a l arger value and rebuild
the m odel. Use the Solver node in the Simulink model Configuration
Parameters dialog.
Remember that I/O can add significant latency to your model. You can use
the xPC Target Interactive Guide
(
http://www.mathworks.com/support/product/XP/productnews/-
interactive_guide/xPC_Target_Interactive_Guide.html
)
to find latency numbers for boards supported by the b lock library. For
example, if your application includes the National Instruments
®
PCI-6713
board, and you want to use four outputs.
1 Look up the board in the xPC T arget Interactive Guide.
From the table, the D/A latency is
1+2.4N.
2 To get the latency for four outputs, calculate the latency
1+(2.4 x 4) = 10.6 microseconds
3 Include this value in your sample time calculations.
• Run the target application on a target PC with a faster processor.
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