Echelon IzoT BACnet Developes - Manual (Page 17)

Refer to the sample source code, in particular BACsimple.nc to see how
this is used.
3. BAClon\mapping.nc
a. This file contains the actual mapping tables that map Network Variables to
BACnet Objects
4. BAClon\mapping.h
a. A header file that contains mapping macros as used by mapping.nc. It can be
extended by the user if required to support UNVTs etc.
Mapping BACnet Objects to Network Variables
Network Variables are mapped to BACnet Objects via entries in this file. There are 4
tables, one table for each BACnet Object type (AI, AO, etc.). Each table has entries,
described in order below:
1. Mapping type - mapAnaTooSNVT_temp_p ( )
This is a C macro that maps the BACnet Object Type to the SNVT type. This
example obviously maps a BACnet Analog Input or Output to a SNVT_temp_p.
Note that SNVT_temp_p is a ‘simple’ Network Variable, a complex case is
described below.
2. Description
Any text string will suffice here. BACnet string lengths are limited to 32
characters.
3. L ON W ORKS Network Variable name
Mapping BACnet Objects to non-Network Variables
“Normal” Variables are mapped in a very similar fashion to Network Variables. Different
macro names are used. For reference, these can be seen in the sample mapping.nc files.
An example is provided here:
mapAnaToNormalVarFloat ( "Loopback Analog Float:AI", floatLoopback ),
mapAnaToNormalVarSShort ( "Loopback Analog Int8:AI", int8Loopback ),
Using BACnet and LONWORKS with the FT 6000 EVK 17