Echelon FTXL - Manual (Page 196)

184 Determining Memory Usage for FTXL Applications
Table 48. RAM Usage per Application Buffer
Application Buffer Type Bytes Required
Input buffer 1710
Output nonpriority buffer 1118
Output priority buffer 1118
The default numbers for each type of buffer are: 5 input buffers, 5 output
nonpriority buffers, and 1 output priority buffer. Thus, the RAM usage for the
default number of application buffers is approximately 15 KB.
Memory for L
ON
W
ORKS
Resources
Each FTXL device uses L ON W ORKS resources, such as network variables defined
for the device, address table entries, and aliases supported by the device.
The FTXL LonTalk protocol stack allocates memory only for resources that are in
use. For example, it allocates memory for address table entries only if the
address is bound. However, when you calculate memory requirements, you
should assume that all resources are in use.
Table 49 lists the amount of memory required for each type of L
ON W ORKS
resource. The number of bytes required for each type of resource is an estimate;
you should round these numbers upward when you use them in memory usage
calculations. For example, as network variables can vary in their actual sizes, so
the table uses an average value.
Table 49. RAM Usage per LonWorks Resource
Resource Type Bytes Required
Static network variable 320 + SD_length + NV_length
Dynamic network variable 331 + SD_length + NV_length
Alias 220
Address table entry 67
Notes:
• SD_length is the length of the self-documentation string for the network
variable
• NV_length is the declared size of the network variable (for changeable-
type network variables, NV_length is the maximum size of the network
variable)
In addition to RAM, L ON W ORKS resources also require memory for constant data.
This constant data must be included in both the total RAM size and the total
flash memory size, because all of the constant data is typically loaded from flash
memory into RAM. Table 50 on page 185 lists the amount of flash memory