Echelon LNS DDE Server - Manual (Page 106)

Properties
The LNS DDE Server provides access to additional properties besides the network
variable, configuration property, and message values described in Chapters 5, 6, and
7. The available properties are dependent on the DDE topic. The following sections
describe these properties.
Specifying a Property
A property topic is specified using the standard or custom topic format described in
Chapter 4. The topic specifies a category of properties, and the item includes the
property name. The following table lists the topic type, item syntax, and example
application, topic, and item specifications for each category.
Category Topic Type Item Syntax Example Specifications
System
Properties System Property Application : LNSDDE
Topic : LNS DDE Test.System
Item : Point.InError
Device and
Router
Properties Dev Device.property Application : LNSDDE
Topic : LNS DDE Test.HVAC.Dev
Item : AO –1.State
LonMark
Object
Properties LM Device.lmo.property Application : LNSDDE
Topic : LNS DDE Test.HVAC.LM
Item : AO –1.SA Temp PID.Request.Override
Point
Properties LMNV, DevNV, Netvar,
NV, DevCP, LMCP,
LMNVCP, DevNVP, or
NVCP Device[.lmo].nv.property
or
device[.lmo][.nv].cp.property Application : LNSDDE
Topic : LNS DDE Test.HVAC.LMNV
Item: AI –1.SA Temp.Analog.DDE_ReadCount
System Properties
System properties provide access to values that apply to a entire LNS network.
The properties are accessed through the system topic, using the following syntax:
Network_name.system
The network_name is the name of the network as defined in the LNS database.
It is case sensitive.
Point.Count R Number of points accessed in the network.
The count is not exact. The server keeps all points ever accessed in a single device in the
point cache for as long as at least one point is still accessed in the same device. After the
last point is no longer accessed, there is a delay of about 15 seconds until the device and all
points belonging to it are deleted from the LNS DDE Server point cache, and the count of
points is decreased.
Point.Active R Number of points currently being accessed in the network.
The active count is not identical to the total count of points accessed. The points marked
active are the points that are currently being read from devices or the LNS database.
8-2 Using Properties