Echelon FTXL - Manual (Page 195)

FTXL User’s Guide 183
call to the LonInit() function (you could also call it after the FTXL device is
commissioned or during peak activity). For the FTXL_Simple_0.elf file shown
above, the uordblocks field is 134 244 bytes (131 KB). Thus, the RAM
requirement for the application includes the 593 496 bytes from the flash
requirement plus the 134 244 bytes from the heap requirement, for a total RAM
requirement of 727 740 bytes (711 KB).
Remember that the flash and RAM requirements are estimates, because a
production application will likely not include the malloc.h file, nor call the
mallinfo() function and associated printf() functions. In addition, for some
applications, not all of the code and uninitialized data need to reside both in flash
and RAM.
Memory Use for Transactions
The FTXL LonTalk protocol stack allocates memory for transactions at runtime,
as they are needed. On the Stack Configuration page of the LonTalk Interface
Developer utility, you can specify a maximum allowed values for the number of
simultaneous receive transactions and for the number of simultaneous transmit
transactions. These values limit the amount of memory that the FTXL LonTalk
protocol stack allocates for transactions.
Table 47 lists the amount of memory required for each type of transaction. The
number of bytes required for each type of transaction is an estimate; you should
round these numbers upward when you use them in memory usage calculations.
Table 47. RAM Usage per Transaction Record
Transaction Type Bytes Required
Transmit transaction 196
Receive Transaction 400
Memory Use for Buffers
The Buffer Configuration page of the LonTalk Interface Developer utility allows
you to specify the number of input, output, and priority output application
buffers that your FTXL application should use. The values that you specify in
the utility are defined in the FtxlDev.h file that the utility generates.
The FTXL LonTalk protocol stack uses the number of application buffers that you
specify to allocate memory for both the application buffers and related internal
buffers. Some of the internal buffers are allocated in advance, and some are
allocated on an as-needed basis.
Table 48 on page 184 lists the amount of memory required for each type of
application buffer. The number of bytes required for each type of application
buffer is an estimate; you should round these numbers upward when you use
them in memory usage calculations.