Installation manual

Publication 1747-RM001G-EN-P - November 2008
C-4 Memory Usage
Estimating Total Memory Usage of Your System Using a Fixed or
SLC 5/01 Processor
__________ 1. Calculate the total instruction words used by the instructions in your program and enter the result.
Refer to the table on page C-2.
__________ 2. Multiply the total number of rungs by 0.375 and enter the result.
__________ 3. Multiply the total number of data words (excluding the status field and I/O data words) by 0.25 and
enter the result.
__________ 4. Add 1 word for each data table file and enter the result
__________ 5. Multiply the highest numbered program file used by 2 and enter the result.
__________ 6. Multiply the total number of I/O data words by 0.75 and enter the result.
__________ 7. Multiply the total number of I/O slots, used or unused, by 0.75 and enter the result.
__________ 8. To account for processor overhead, enter 65 if you are using a fixed controller, enter 67 if you are
using a 1747-L511 or 1747-L514.
Total: __________ 9. Total steps 1 through 8. This is the estimated total memory usage of your application system.
Remember, this is an estimate, actual compiled programs may differ by ±12%.
10. If you wish to determine the estimated amount of memory remaining in the processor you have
selected, do the following:
If you are using a fixed controller or 1747-L511, subtract the total from 1024. If you are using a
1747-L514, subtract the total from 4096.
The result of this calculation will be the estimated total memory remaining in your selected
processor.
TIP
The calculated memory usage may vary from the
actual compiled program by ±12%.