Rockwell Automation 1761 MicroLogix 1000 Programmable Controllers - Manual (Page 313)

Reference
Programming Reference
B–25
Estimating Memory Usage for Your Control System
Use the following to calculate memory usage for your control system.
The result of this calculation will be the estimated
total memory remaining in your selected
controller.
Subtract the total memory usage from 1024.
Note The calculated memory usage may vary from the
actual compiled program by
±
12%.
1. Determine the total instruction words used by the
instructions in your program and enter the result.
Refer to the table on page B–21.
2. Multiply the total number of rungs by 0.75 and
enter the result. Do not count the END rungs in
each file.
3. To account for controller overhead, use 177.
4. To account for application data, use 110.
5. Total steps 1 through 4. This is the estimated total
memory usage of your application system.
Remember, this is an estimate, actual compiled
programs may differ by
±
12%.
6. To determine the estimated amount of memory
remaining in the controller you have selected, do
the following:
Total Memory Usage:
177
110
1024
-
Total Memory
Remaining:
Total Memory Usage
(from above):