User Manual

198 Appendix E: Appendix E
Determining Memory Usage for LonTalk
Stack Applications
Node Data Bytes Required
Notes:
• Node_SD_length is the length of the self-documentation string for the
node
• NV_SD_length is the length of the self-documentation string for all
network variables (both static and dynamic)
The following table describes the amount of non-volatile memory required for the
application data.
Application Data Bytes Required
Header 16
Configuration Network Variables
(
)
∑
j
j
CPNVlen
File-based CPs File_length
Application-specific data Data_length
Notes:
• File-based CPs are configuration properties that are defined in
configuration files
• CPNVlen
j
is the configuration network variable length of a specific
configuration NV value – the application data includes the sum of the
configuration NV lengths of all configuration NV values
• File_length is the size of the writeable configuration file for the
configuration properties
• Data_length is the length of any addition application-specific data
Memory Usage Examples for Data
The following table shows the approximate amount of RAM that is required for
various example LonTalk Stack applications. Each row of the table represents a
different application by varying the number of network variables, transmit
transactions, receive transactions, aliases, and address table entries. The values
for all columns except the network variable column represent values calculated
by the LonTalk Interface Developer utility.
Note: The listed amounts of memory are based on FTXL device application
requirements. These numbers may vary for LonTalk Stack device applications,
and the may differ based on the host processor and the compliler.
The table assumes that each network variable has a length of 2 bytes, and has a
5-byte self-documentation string associated with it. The table also assumes the
default number of application buffers (5 input buffers, 5 output nonpriority
buffers, and 1 output priority buffer). Varying the number of application buffers