Reference Manual
748384-C
September 2003
Rosemount Analytical Inc. A Division of Emerson Process Management
Introduction 1-5
NGA2000 Reference
Binding
Binding is the process of connecting various
variables in the analyzer module with
equivalent variables in the I/O modules.
Normally the LON expects to bind individual
variables, but the NGA system simplifies
this by binding whole groups of them at
once. Once they are bound, an update to
one variable on one node will automatically
cause the variable bound to it on another
node to be updated as well. This allows the
I/O module to track the main reading (PVA)
of the analyzer automatically, and it allows
the I/O module to change the range of the
analyzer by updating its CRANGE0 vari-
able, thus changing the analyzer's
CRANGE variable which is bound to
CRANGE0.
Subsequent revisions of the control module
software (from V2.3) will allow you to bind
all the I/O modules at once, rather than
making you bind each one, waiting for the
system to reset between each module.
Binding is only necessary for systems with
I/O modules. Systems that have no control
module, and which rely on a computer to
get data from analyzers, do not need to do
any binding.
Controller Module Memory Issues
The control module has a restricted amount
of memory, just as do all computers. It can
therefore handle only a certain number of
analyzers and I/O modules. It stores all of
the data from each module within itself. If
an analyzer module is removed and re-
placed, the control module will remember
the data from the analyzer, so if the ana-
lyzer is replaced the control module can
recognize it and bring it back on line imme-
diately. However this also means that the
control module will remember all the ana-
lyzers it has ever seen, so that it will even-
tually run out of memory. The limit with a
V2.2 control module is about 6 analyzers.
With a V3.0 control module it is 15 analyz-
ers.
Replacing an Analyzer
If you replace an analyzer with a new one,
you will have to reset the control module so
that it can recognize the new analyzer. If
you run out of memory in the process, the
control module may hang and not complete
the initialization. In this case, press the
"RE-INIT" button and rebind all the I/O
module all over again. If the control module
is so lost that the "RE-INIT" button doesn't
work, remove power from it briefly and re-
place the power, and then press the
"RE-INIT" button as soon as it appears.
Then go through the binding process again.
This procedure should be improved with the
V3.0 control module software.
Multiple Control Modules
In V3.1 or earlier, it is not possible to con-
nect more than one control module on a
system. If it is desired to connect them to a
single computer, it is necessary to use
"Routers" (a component sold by Echelon
Corporation) to isolate the control modules
from each other.