Echelon LonTal Stack - Manual (Page 177)

LonTalk Stack Developer’s Guide 165
sync | synchronized
Specifies that all values assigned to this network variable must be
propagated, and in their original order. This flag is passed on to your
LonTalk Stack application, and must be enforced by your application.
This keyword is mutually exclusive with the polled keyword.
polled
For an output network variable, specifies that the value of the network
variable is to be sent only in response to a poll request from a device that
reads this network variable. When this keyword is omitted for an output
network variable, its value is propagated over the network every time the
variable is assigned a value. However, any reader device can always poll the
outputs of writer devices to which it is connected, whether or not the output
is declared as polled.
Unlike for native Neuron C, the polled network modifier is permitted for
input network variables (as well as output network variables) in model files.
The polled modifier, when used with the declaration of an input network
variable, indicates that the application uses the LonPollNv() LonTalk API
function with this network variable.
If you use the NodeBuilder Code Wizard to generate your model file, the code
wizard does not insert the polled modifier for input network variables. You
can edit the code produced by the code wizard to add the polled modifier.
You can perform all normal network variable operations with a polled input
network variable; however, the LonPollNv() function requires the network
variable to be connected to one or more output network variables. If you call
LonPollNv() without having made such a connection, you will not receive
any data. If you call LonPollNv() for a network variable that is not an input
network variable and that has not been declared with the polled modifier,
the LonPollNv() function returns an error.
The polled modifier can cause an address table entry to be used to allow the
input to poll a group connection to the input.
This keyword is mutually exclusive with the sync keyword.
changeable_type
Declares that the network variable can have its type changed by a network
management tool. The changeable_type modifier can only appear once per
network variable declaration, and must appear after the sync or polled
modifiers, if either is used.
sd_string ( C-string-const )
Sets a network variable's self-documentation (SD) string of up to 1023
characters. This modifier can only appear once per network variable
declaration. If any of the sync, polled, or changeable_type keywords is
used, then the sd_string must follow these other keywords. Concatenated
string constants are permitted. Each variable's SD string can have a
maximum length of 1023 bytes.
The use of any of the following Neuron C keywords causes the compiler to
take control over the generation of self-documentation strings: fblock,
config_prop, cp, device_properties, nv_properties, fblock_properties,
or cp_family.