Working with Simulink Blocks
Modeling Instantaneous Events
When working with SimElectronics software, your model may
include Simulink blocks that create instantaneous changes to
the physical system inputs through the Simulink-PS Converter block,
such as those associated with events or discrete sampling. When you
build this type of model, make sure the corresponding zero crossings
are generated.
Many blocks in the Simulink library generate these zero
crossings by default. For example, the Pulse Generator block produces
a discrete-time output by default, and generates the corresponding
zero crossings. To model instantaneous events, select Use
local settings or Enable all for
the Zero crossing control option under the model's
Solver Configuration Parameters to generate zero crossings. For more
information about zero crossing control, see Zero-crossing control in
the Simulink documentation.
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Using Simulink Blocks to Model Physical Components
To run a fast simulation that approximates the behavior of the
physical components in a system, you may want to use Simulink blocks
to model of one or more physical components.
The Modeling
an Integrated Circuit demo uses Simulink to model a physical
component. The Simulink Logical Operator block implements the
behavioral model of the two-input NOR gate, as shown in the following
figure.
Using Simulink in this manner introduces algebraic loops,
unless you place a lag somewhere between the physical signal inputs
and outputs. In this case, a first-order lag is included in the Logic2Volts
& Propagation Delay subsystem to represent the delay due to gate
capacitances. For applications where no lag is required, use blocks
from the Physical Signals sublibrary in the Simscape Foundation
Library to implement the desired functionality.
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 | Specifying Parameters that Affect All SPICE-Compatible Blocks
| | Simulating an Electronic System |  |
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