Echelon Neuron C - Manual (Page 206)

186 Functional Block Declarations
the program. The array entry is an unsigned short. Its declaration, in the
<echelon.h> file, is:
extern const unsigned short fblock_index_map[ ];
The value for each network variable is set to the global index of the functional
block of which it is a member. If the network variable is not a member of any
functional block, the value for its entry in the fblock_index_map array is set to
the value 0xFF.
Accessing Members and Properties of a
Functional Block from a Program
The network variable members and configuration property (implemented as
network variable) members of a functional block can be accessed from a program
just as any other variable can be accessed. For example, they can be used in
expressions, as function parameters, or as operands of the address operator or
the increment operator. To access a network variable member of a functional
block, or to access a network variable configuration property of a functional block,
the network variable reference can be used in the program just as any other
variable would be.
However, to use a CP family member, you must specify which family member is
being accessed, because more than one functional block could have a member
from the same CP family. The syntax for accessing a configuration property from
a functional block’s property list is:
fb-context :: property-identifier [ index-expr ]
fb-context :: property-identifier
fb-context : identifier [ index-expr ]
identifier
The particular family member is identified by a qualifier that precedes it. This
qualifier is called the
context . The context is followed by two consecutive colon
characters, and then the name of the property. Because there cannot be two or
more properties with the same SCPT or UCPT type that apply to the same
functional block, this restriction means that each property is unique within a
particular context. The context uniquely identifies the property. For example, a
functional block array, fba, with 10 elements, could be declared with a property
list referencing a CP family named xyz. There would then be 10 different
members of the CP family xyz, all with the same name. However, adding the
context, such as fba[4]::xyz, or fba[j]::xyz, uniquely identifies the CP family
member.
Example:
// Continuing from the example earlier in the chapter
// that declared MyFb1[2] and MyFb2[2] ...
void f(void)
{
MyFb1[0]::nvoData = muldiv( rawData,
MyFb1[0]::cpGain.multiplier,
MyFb1[0]::cpGain.divider
);
}