Echelon Neuron C - Manual (Page 118)

106 Using Functional Blocks to Implement a Device Interface
added per line. In this way, a functional block can contain an NV array with the
elements declared as consecutive NV members.
At the end of the member list there is an optional item that permits the
specification of a director function. The director function specification begins
with the director keyword, followed by the identifier that is the name of the
function, and ends with a semicolon.
Example:
network output SNVT_amp nvoAmpere;
extern void MeterDirector(unsigned fbIdx, unsigned cmd);
fblock SFPTopenLoopSensor {
nvoAmpere implements nvoValue;
director MeterDirector;
} fbAmpereMeter;
See The Director Function on page 113 for more details about directors.
After the member list, the functional block declaration continues with the name
of the functional block itself. A functional block can be a single declaration, or it
can be a singly dimensioned array.
If the functional block is implemented as an array as shown in the example
below, then each network variable that implements a member of that functional
block must be declared as an array of at least the same size. When implementing
the fblock array’s member with an array network variable element, the starting
index of the first network variable array element in the range of array elements
must be provided in the implements statement. The Neuron C compiler
automatically adds the following network variable array elements to the fblock
array elements, distributing the elements consecutively.
Example:
network output SNVT_lev_percent nvoValue[6];
// The following declares an array of four fblocks,
// with "nvoAnalog" members implemented by the
// network variables nvoValue[2] .. nvoValue[5],
// respectively.
fblock SFPTanalogInput {
nvoValue[2] implements nvoAnalog;
} myFb[4];
You can provide an optional external name for each functional block. To specify
an external name, use the external_name keyword, followed by a string of up to
16 characters in parentheses. The string becomes part of the device interface
which is exposed to network tools.
Alternatively, you can provide an optional external name that is specified by a
language string in a resource file using the external_resource_name keyword. In
this case, the device interface information contains a scope and index pair (the
first number is a scope, then a colon character, then the second number is an
index). The scope and index pair identifies a language string in a resource file,
which a network tool can access for a language-dependent name of the functional
block. You can use the scope and index pair to reduce memory requirements and