Echelon LonTal Stack - Manual (Page 83)

LonTalk Stack Developer’s Guide 71
predefines the _FTXL and _MODEL_FILE macros, so that you can use #ifdef or
#ifndef compiler directives to control conditional compilation of source code that
is used for standard Neuron C compilation and as an LonTalk Stack model file.
All constructs not specifically mentioned as unacceptable or ignored are
acceptable.
Anonymous Top-Level Types
Anonymous top-level types are not valid. The following Neuron C construct is
not valid:
network output struct {int a; int b;} nvoZorro;
This statement is not valid because the type of the nvoZorro network variable
does not have a name. The LonTalk Interface Developer utility issues an error
when it detects such a construct.
Using a named type solves the problem, for example:
typedef struct {
int
a;
int b;
} Zorro;
network output Zorro nvoZorro;
The use of anonymous sub-types is permitted. For example, the LonTalk
Interface Developer utility allows the following type definition:
typedef struct {
int a;
int b;
struct
{
long x;
long y;
long z;
} c;
} Zorro;
network output Zorro nvoZorro;
Legacy Neuron C Constructs
You must use the Neuron C Version 2.1 syntax described in this manual. You
cannot use legacy Neuron C constructs for defining L ON M ARK -compliant
interfaces. That is, you cannot use the config modifier for network variables,
and you cannot use Neuron C legacy syntax for declaring functional blocks or
configuration properties. The legacy syntax used an sd_string() modifier
containing a string that starts with a ‘&’ or ‘@’ character.
Using Authentication for Network Variables
Authentication is a special acknowledged service between one source device and
one or more (up to 63) destination devices. Authentication is used by the
destination devices to verify the identity of the source device. This type of service
is useful, for example, if a device containing an electronic lock receives a message
to open the lock. By using authentication, the electronic lock device can verify