Echelon LNS - Manual (Page 154)

LNS Programmer's Guide 140
nviValue
nvi_NV1
Device One
Device Three
Device Two
nviTemp
nviTemp2
Hub Network Variable
Target Network Variables
Device Four
nvoStatus
Device Six
Device Five
Target Network Variables
nvoSetPoint
nvoControl
Hub Network Variable
Figure 6.4 Example Connections
Connection Rules
There are several rules you need to consider when creating connections. For network
variable connections, the LNS Object Server enforces these rules:
• Network variables can only be connected to network variables.
• The hub must be either the only input or the only output in the
connection.
• There must be one hub, and at least one target, in each connection.
• All the network variables in the connection must have compatible types.
If SNVTs are used, the LNS Object Server will validate that all members
are the same SNVT type. For non-standard network variables types, the
LNS Object Server will verify that all members are the same length, if
length information is available. If length information for a network
variable is not available, the LNS Object Server will treat the network
variable as typeless. The LNS Object Server allows typeless network
variables to be bound to any other network variable type. It is the
responsibility of the LNS application to prevent nonsensical connections
from being formed from typeless network variables.
• A polled output network variable can only be connected to polling input
network variables.
• Authenticated inputs can only be bound to authenticated outputs.
Authenticated outputs may be connected to unauthenticated inputs.
• Devices can have no more than one output and, in some cases, one input
network variable within a given connection group (i.e. those connections
that share the same network variable selector)
The LNS Object Server allows the use of network variable aliases. Aliasing allows a
network variable to have multiple selector values. In addition, the relaxed connection
constraints that are available with newer versions of the Neuron Chip firmware
sometimes allow selector values to be used more than twice in a given device. Alias table