Connection Type attribute

A connection may be explicitly specified as either VIRTUAL or PHYSICAL, but not both. For example:

connect ? sender[2]      receiver[0]  virtual

connect ? AtoD_driver[0] FIRfilter[0] physical

Physical connections are directly mapped onto wires;. virtual connections are more flexible. See here for more about the differences between virtual and physical connections. Some implementations support only PHYSICAL connections.

If neither VIRTUAL nor PHYSICAL is specified, the configurer uses a default setting, which is determined as follows. Connections are normally virtual by default. This behaviour can be changed using the DEFAULT CONNECT statement. The configurer command-line option –p can be used to make all connections physical by default. The configurer reports any clashes between these different ways of specifying the default type of a connection.

Sometimes the configurer is not able to make a connection virtual. This can happen if either of the following conditions is true:

If this happens, the connection falls back to being physical. If a virtual connection was explicitly requested (using the VIRTUAL attribute), the configurer gives a warning message. If there are not enough spare wires in the configuration to accommodate an extra physical connection, the configurer gives an error message.