Allen-Bradley Logix5000 Series Application Book page 20

20 CompactFlash Commands
Publication LOGIX-AP007B-EN-P - January 2007
For example, the tag MYDINTS[100] will be 4 times 100 elements, or 400
bytes of data. Similarly, if a UDT is used, 1 instance of that UDT will be the
sum of the sizes of all the data types within the structure.
When reading or writing to the CompactFlash card, it is
TIP
best to use UDT tags. This lets you mix different data types
together and lets you know the number of bytes that will
need to be transferred to and from the card.
The following is a UDT that is the recipe for making waffles.
As you can see, the total size of the recipe is 72 bytes. This means that you
would want to read or write 72 bytes of data to the CompactFlash card. This
would be entered into the Bytes_to_RW element of the CF_File_Structure
UDT.