Notifying, Monitoring, and Reactive Ports

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Overview of Signal Input Ports of SimEvents Blocks Notifying Ports Monitoring Ports Reactive Ports Connecting Event-Based Signal Generators to Reactive Ports

Overview of Signal Input Ports of SimEvents Blocks

Signal input ports of SimEvents blocks fall into these categories:

• Notifying ports, which notify the preceding block when a certain event has occurred

• Monitoring ports, which help you observe signal values

• Reactive ports, which listen for updates or changes in the input signal and cause an appropriate reaction in the block possessing the port

The distinctions are relevant when you use the Event-Based Random Number or Event-Based Sequence block. For details, see these topics:

• Event-Based Random Number reference page

• Event-Based Sequence reference page

• Generating Random Signals

• Using Data Sets to Create Event-Based Signals

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Notifying Ports

Notifying ports, listed in the table below, notify the preceding block when a certain event has occurred. When the preceding block is the Event-Based Random Number or Event-Based Sequence block, it responds to the notification by generating a new output value. Other blocks ignore the notification.

List of Notifying Ports

Signal Input Port	Block	Generate New Output Value Upon
Attribute name (e.g. Attribute1, Attribute2)	Set Attribute	Entity arrival
in	Signal Latch	Write event
e1, e2	Entity Departure Function-Call Generator	Entity arrival
	Signal-Based Function-Call Generator	Relevant signal-based event, depending on configuration of block
t	Signal-Based Function-Call Generator	Relevant signal-based event, depending on configuration of block
t	Infinite Server	Entity arrival
	N-Server	Entity arrival
	Single Server	Entity arrival
t	Time-Based Entity Generator	Simulation start and subsequent entity departures
ti	Schedule Timeout	Entity arrival
x	X-Y Signal Scope	Sample time hit at in signal input port

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Monitoring Ports

Monitoring ports, listed in the table below, help you observe signal values. Optionally, you can use a branch line to connect the Event-Based Random Number or Event-Based Sequence block to one or more monitoring ports. These connections do not cause the block to generate a new output, but merely enable you to observe the signal.

List of Monitoring Ports

Signal Input Port	Block
Unlabeled	Discrete Event Signal to Workspace
in	Signal Scope
	X-Y Signal Scope
ts, tr, vc	Instantaneous Event Counting Scope
Unlabeled	Event to Timed Signal

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Reactive Ports

Reactive ports, listed in the table below, listen for relevant updates in the input signal and cause an appropriate reaction in the block possessing the port. For example, the p port on a switch listens for changes in the input signal; the block reacts by selecting a new switch port.

List of Reactive Ports

Signal Input Port	Block	Relevant Update
en	Enabled Gate	Value change from nonpositive to positive, and vice versa
p	Input Switch	Value change
	Output Switch
	Path Combiner
ts, tr, vc	Entity Departure Counter	Sample time hit at ts port Appropriate trigger at tr port Appropriate value change at vc port
	Event-Based Entity Generator
	Release Gate
	Signal-Based Function-Call Generator
	Signal-Based Function-Call Event Generator
wts, wtr, wvc, rts, rtr, rvc	Signal Latch	Sample time hit at wts or rts port Appropriate trigger at wtr or rtr port Appropriate value change at wvc or rvc port
Unlabeled input port	Event Filter	Depends on block parameter values. Choices are: Sample time hit Appropriate trigger Appropriate value change
Unlabeled input port	Initial Value	Sample time hit

For triggers and value changes, "appropriate" refers to the direction you specify in a Type of change in signal value or Trigger type parameter in the block's dialog box.

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Connecting Event-Based Signal Generators to Reactive Ports

To connect an event-based signal generator to a reactive port, you must use a workaround because you cannot connect the Event-Based Random Number block directly to a reactive input port of a SimEvents block or indirectly, via a single-input-single-output (SISO) block that supports event-based input signals.

The following model shows an invalid connection of the Event-Based Random Number block.

In this model, the Event-Based Random Number block is directly connected to the p input port of an Output Switch block. The p input port of the Output Switch block is a reactive port. This connection is invalid because the Event-Based Random Number block cannot infer from the p input port of the Output Switch block when to generate a new random number. The Output Switch block is designed to listen for changes in its p input signal and respond when a change occurs. The Output Switch cannot cause changes in the input signal value or inform the random number generator when to generate a new random number.

The following model shows a workaround to this invalid connection.

In this workaround, the Event-Based Random Number block is not directly connected to the p input port of the Output Switch block. Instead, a Signal Latch block stores each value that the Event-Based Random Number block generates.

When an entity departs the Output Switch block, the #d output signal of that block increments by a value of 1 and triggers a write-to-memory event in the Signal Latch block. In this model, the value of the Read from memory upon parameter of the Signal Latch block is set to Write to memory event. This setting means that each time the Event-Based Random Number block writes a new value to the Signal Latch block, the Signal Latch block outputs its current stored value to the p input port of the Output Switch block.

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Notifications and Queries Among Blocks

Interleaving of Block Operations

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