Rockwell Automation D64046.5.1 U MNL WIN DDMC - Manual (Page 153)

Reference Information
Appendix A
A-9
Amount of Program File Memory Needed for DFA CAR File
A DFA instruction uses program memory for the contents of the CAR file.
(The DFA CAR uses 223 words of program memory in the PLC-5
processor and 210 words of program memory in the PLC-5/250 processor.)
Therefore, the total amount of program memory used is different
depending on if you are using a PLC–5 processor or a PLC-5/250
processor.
PLC-5 Processor
To determine the amount of program memory used per DFA instruction in
the PLC-5 processor, use the following formula:
17 words + 4 words per I/O programmed
–or–
17 words + (4 (# of inputs defined))
For example, consider that we have 2 DFA instructions with 4 inputs each:
2 DFA instructions (17 words + (4 (4)) =
2 (17 + 16) =
2 (33) =
66 words of program file memory
PLC-5/250 Processor
To determine the amount of program memory used per DFA instruction in
the PLC-5/250 processor, use the formula from Table A.L depending on
your number of I/O.
Table A.L
Formulas for Determining Amount of Program File Memory for DFA
Instructions in the PLC-5/250
Number of I/O: Formula:
8 194 words + (number of I/O points defined x 20)
16 224 words + (number of I/O points defined x 20)
32 288 words + (number of I/O points defined x 20)