User`s guide

Polling Mode
10-11
• Signal tracing through scope objects — Neither through scope objects of type
host (xPC Target Explorer or scripts) or type target (scopes on the target
screen if property
Enable target scope is enabled)
• Signal monitoring — You cannot run a GUI interface on the host PC using
an environment that depends on communication between the host and target
computers.
• Applications using the xPC Target API
• The Internet browser interface
• Other utilities like
xpctargetspy
The only rapid-prototyping feature available is signal logging, because the
acquisition of signal data runs independently from the host, and logged data is
retrieved only after the execution is stopped. Nevertheless, being able to log
data allows gathering good enough information about the behavior of the target
application. Signal logging becomes a very important feature in polling mode.
Multirate Simulink Models Cannot Be Executed in Multitasking Mode on
the Target PC
Because of the polling mode execution scheme, executing Simulink-based
target applications in multitasking mode is not possible. The modeling of
function-call subsystems to handle asynchronous events (interrupts) is not
possible either. This can be a hard restriction, especially for multirate systems.
Multirate systems can be executed in single-tasking mode, but because of its
sequential execution scheme for all subsystems with different rates, the CPU
will most likely overload for the given base sample time. As an important
consequence, polling mode is only a feasible alternative to interrupt mode if the
model has a single rate or if it can be converted to a single-rate model. A
single-rate model implies continuous states only, discrete states only, or mixed
continuous and discrete states, if the continuous and discrete subsystems have
the same rate. Use the
Format -> Sample time color feature of Simulink to
check for the single rate requirement. Additionally, set the tasking mode
property in the
Simulation menu Configuration Parameters -> Solver pane
to
SingleTasking to avoid a possible switch to multitasking mode. For more
information on single-tasking mode compared to multitasking mode, see the
Real-Time Workshop user’s documentation.