Echelon IzoT Commissioning Tool - Manual (Page 24)

to be performed on the values stored in the network variables. For example, a configuration property
may specify a minimum change that must occur on a physical input to a device before the
corresponding output network variable is updated. Like network variables, configuration properties
have types that determine the type and format of the data they contain.
Functional Blocks
Applications in devices are divided into one or more functional blocks. A functional block is a
collection of network variables and configuration properties that work together to perform a single
task. These network variables and configuration properties are called the functional block members.
For example, a digital input device could have four digital input functional blocks that contain the
configuration properties and output network variable members for each of the four hardware digital
inputs on the device. A functional block is an implementation of a functional profile.
Functional Profiles
A functional profile defines mandatory and optional network variable and configuration property
members for a type of functional block. For example, the standard functional profile for a light
actuator has mandatory SNVT_switch input and output network variables, optional
SNVT_elapsed_tm and SNVT_elec_kwh output network variables, and a number of optional
configuration properties. The following diagram illustrates the components of the standard light
actuator functional profile:
Lamp Actuator
Mandatory network variables
Configuration properties
Optional network variables
nviLampValue
SNVT_switch
nv1
SFPTLampActuator
nvoLampValueFb
SNVT_switch
nv2
nvoEnergyCnt
SNVT_elec_kwh
nv4
nvoRunHours
SNVT_elapsed_tm
nv3
Mandatory Optional
SCPT_location
SCPTinFbDly
SCPT_def_output
SCPTrunHrInit
SCPTrunHrAlarm
SCPTenrgyCntInit
When a functional block is created from a functional profile, the application designer can determine
which of the optional configuration properties and network variables to implement.
Standard Network Variable and Configuration Property Types
Every network variable and configuration property has a type, which determines the content and
structure of the data. To enable devices from different manufacturers to interoperate, the following
standard types are defined:
• Standard Network Variable Types (SNVTs, pronounced snivits). SNVTs contain many common
operational data types. For example, SNVT_temp_p is a network variable type for network
variables containing temperature as a fixed-point number.
8 Introduction