Trane Engineered Smoke Control System, Application Manual

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Chapter 8 Network variable bindings
130 BAS-APG001-EN
UUKL binding list (automatic self-test trigger and
status)
Table 37 shows an example list of actuator failure status bindings. Only
dedicated smoke control systems require a scheduled self-testing. Once
the self-test is triggered, a status signal is sent to the panel trouble LED
to blink.
Custom binding report
It is strongly recommended that a custom binding report be done during
and at the end of each custom binding session. The *.csv (comma
separated variables) is the most useful type for this report. It can easily
be opened as a spreadsheet and formatted. If it is necessary to repair the
custom bindings later, this file can be used as a resource to recreate the
custom bindings.
Understanding bindings
Network variable (NV) bindings provide a valuable way to share data on
a LonTalk
®
link, but there are some limitations to keep in mind during
the system design process. This section will help you understand the
essential concepts involved in bindings, as well as their limitations.
The Echelon Corporation, the company that created LonWorks
®
and the
LonTalk protocol, refers to bindings as connections . Echelon defines
connections as “the implicit addressing established during binding. A
connection links one or more logical outputs, network variables, to one or
more logical inputs.”
Bindings provide a very efficient way to communicate. Data updates are
sent from the output NV(s) to the input NV(s)
only when necessary . When
they are sent, they get to their destination quickly—typically, in less than
a half-second.
An update to an output NV occurs when either of the following occur:
•
A binary value changes state
•
An analog value changes by more than a pre-programmed delta value
•
A heartbeat timer expires
This peer-to-peer event-driven communications model often provides
better performance than a master-slave and/or scan-type communications
model. It is one of the key advantages of LonTalk.
Table 37. Actuator failure status bindings
Function Originator Network variable Destination
systemSelfTest MP580-2 nvoSwitch13 Mechanical system/nviSwitch36
selfTestEnable Mechanical system nvoSwitch04 MP580-2/nviSwitch05