The network variable initializer, The network variable property list – Echelon FTXL User Manual

Page 150

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138

Neuron C Syntax for the Model File

The Network Variable Initializer

initial-value

or

initializer-list

Specifies an initial value (or values) for the network

variable. All network variables, especially input network
variables, should be initialized to a reasonable default

value.

The initial value should be chosen such that if a device is reset, the initial value
can be used for subsequent calculations prior to the variable’s being updated from

the network, and these calculations will not cause the device to create a

hazardous condition or to create an error condition. Initializers should not be
propagated over the network, regardless of whether the network variables are

declared input or output. See

Network Variable and Configuration Property

Declarations

on page 68 for more information about initializers.

Example:

network input SNVT_temp nv_temp = 2960;

// 23 C, 73.4 F

The Network Variable Property List

A network variable property list declares instances of configuration properties

defined by CP family declarations and configuration network variable
declarations that apply to a network variable.
The syntax for the

nv-property-list

specification is:

nv_properties {

property-reference-list

}

property-reference-list

:

property-reference-list , property-reference

property-reference

property-reference

:

property-identifier

[ =

initializer

] [

range-mod

]

property-identifier

[

range-mod

] [ =

initializer

]

range-mod

:

range_mod_string (

concatenated-string-constant

)

property-identifier

:

[

property-modifier

]

identifier

[

constant-expression

]

[

property-modifier

]

identifier

property-modifier

:

static | global

The network variable property list begins with the

nv_properties

keyword. It

then contains a list of property references, separated by commas, exactly like the

device property list and functional block property lists. Each property reference

must be the name of a previously declared CP family or the name of a previously
declared configuration network variable. The rest of the syntax is very similar to

the device property list and functional block property list syntax.

Following the

property-identifier

, there can be an optional

initializer

, and an

optional

range-mod

.

You cannot have more than one configuration property of any given SCPT or
UCPT type that applies to the same network variable.

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