channel (Z.100)

Concrete graphical grammar

<channel definition area> ::=
<channel symbol>
is associated with {<channel name>
{ [{<channel identifiers> | <block identifier> | <gate> }]
<signal list area> [ <signal list area>] }set }
is connected to
{ <block area> {<block area> | <frame symbol>}
[<channel substructure association area>] }set

<channel identifiers> can be specified if and only if the enclosing diagram is a <block substructure diagram> directly enclosed by a <block definition>. <block identifier> can be specified if and only if the enclosing diagram is a <channel substructure diagram>. The <channel identifiers> identify external channels connected to the <block substructure diagram> delimited by the <frame symbol>. The <block identifier> identifies an external block as a channel endpoint for the <channel substructure diagram> delimited by the <frame symbol>. When the <channel symbol> is connected to a <frame symbol>, then the <gate> it is associated with is a gate defined for that block type by means of a <gate> or a <graphical gate constraint> associated with the block type diagram.

<channel symbol> ::=
<channel symbol 1>
| <channel symbol 2>
| <channel symbol 3>
| <channel symbol 4>
| <channel symbol 5>

<channel symbol 1> ::=

<channel symbol 2> ::=

<channel symbol 3> ::=

<channel symbol 4> ::=

<channel symbol 5> ::=

For each arrowhead on the <channel symbol>, there must be a <signal list area>. A <signal list area> must be unambiguously close enough to the arrowhead to which it is associated.

The arrowheads for <channel symbol 4> and <channel symbol 5> are placed at the end(s) of the channel and indicate that the channel has no delay.

Semantics

A channel represents a transportation route for signals. A channel can be considered as one or two independent unidirectional channel paths between two blocks or between a block and its environment.

The Signal-identifier-set in each Channel-path in the Channel-definition contains the signals that may be conveyed on that Channel-path.

Signals conveyed by channels are delivered to the destination endpoint.

Signals are presented at the destination endpoint of a channel in the same order they have been presented at its origin point. If two or more signals are presented simultaneously to the channel, they are arbitrarily ordered.

A channel with delay may delay the signals conveyed by the channel. That means that a First-In-First-Out (FIFO) delaying queue is associated with each direction in a channel. When a signal is presented to the channel, it is put into the delaying queue. After an indeterminate and non-constant time interval, the first signal instance in the queue is released and given to one of the channels or signal routes which is connected to the channel.

Several channels may exist between the same two endpoints. The same signal type can be conveyed on different channels.

If one endpoint of a channel is a <textual typebased block definition>, the other endpoint may be the same <textual typebased block definition>. The <number of block instances> must then be greater than one for the <textual typebased block definition>.

Model

A channel with both endpoints being gates of one <textual typebased block definition> represents transportation routes from each of the blocks in the set to all other blocks in the set.

A channel with one endpoint being a gate of a <textual typebased block definition> represents individual channels to or from each of the blocks in the set. The individual channels will all have the same delaying property as the expanded channel.