Network variable types (type) – Echelon Neuron C User Manual
Page 183
Neuron C Reference Guide
163
connections can still cause changes to such a
configuration network variable.
eeprom
The network variable is placed in EEPROM or flash
memory instead of RAM. All variables are placed in RAM
by default. EEPROM and flash memory are only
appropriate for variables that change infrequently, due to
the overhead and execution delays inherent in writing
such memory, and due to the limited number of writes for
such memory devices.
far
The network variable is placed in the
far
section of the
variable space. In Neuron C, variables are placed in
near
memory by default, but the
near
memory areas are
limited in space. The maximum size of
near
memory
areas is 256 bytes of RAM and 255 bytes of EEPROM, but
could be less in some circumstances.
offchip
This keyword places the variable in the
off-chip
portion of
the variable space. By default, the linker places variables
in either space as it chooses, depending on availability. If
the requested memory is not available, the link fails.
onchip
This keyword places the variable in the
on-chip
portion of
the variable space. By default, the linker places variables
in either space as it chooses, depending on availability. If
the requested memory is not available, the link fails.
uninit
This keyword prevents compile-time initialization of
variables. This is useful for eeprom variables that should
not or need not be written by program load or reload.
A
different
mechanism,
subject to your network
management tool, is used to determine whether
configuration properties, including configuration network
variables, are initialized after loading or commissioning
the device. The uninit keyword cannot be used to prevent
configuration network variables from being initialized by
the network management tool. See your network tool's
documentation for details.
Network Variable Types (type)
A network variable can be declared using any of the following types:
• A standard network variable type (SNVT) as described in Chapter 3,
How
Devices Communicate Using Network Variables,
of the
Neuron C
Programmer's Guide
. Use of a SNVT promotes interoperability. See
for a list of SNVTs.
• A user network variable type (UNVT) as described in Chapter 3,
How
Devices Communicate Using Network Variables,
of the
Neuron C
Programmer's Guide.
UNVTs are defined using the NodeBuilder
Resource Editor as described in the
NodeBuilder FX User’s Guide.
• Any of the variable types specified in Chapter 1,
Overview,
of the
Neuron C Programmer's Guide
, except for pointers. The types are those
listed below: