Installation manual

Publication 1747-RM001G-EN-P - November 2008
C-10 Memory Usage
Estimating Total Memory Usage of Your System Using a SLC 5/02
Processor
__________ 1. Calculate the total instruction words used by the instructions in your program and enter the result.
Refer to the table on page -7.
__________ 2. Multiply the total number of rungs by 0.375 and enter the result.
__________ 3. If you are using a 1747-L524 and have enabled the Single Step Test mode, multiply the total number
of rung by 0.375 and enter the result.
__________ 4. Multiply the total number of data words (excluding the status file and I/O data words by 0.25 and
enter the result.
__________ 5. Add 1 word for each data table file used and enter the result.
__________ 6. Multiply the highest numbered program file used by 2 and enter the result.
__________ 7. Multiply the total number of I/O data words by 0.75 and enter the result.
__________ 8. Multiply the total number of I/O slots, used or unused, by 0.75 and enter the result.
__________ 9. To account for processor overhead, enter 204
Total: __________ 10. Total steps 1 through 9. This is the estimated total memory usage of your application system.
Remember, this is an estimate, actual compiled programs may differ by ±12%.
11. 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 1747-L524, 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%.