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49 Publication LOGIX-AP007B-EN-P - January 2007

Appendix

Expand the Code to Support More than 4500

Bytes of Data

Introduction

This appendix describes how to expand the code to support more than 4500

bytes of data.

Modify the Application to

Access More Data

The baseline application supports reading or writing 4500 bytes of data to

CompactFlash card. If you need to access more data, modify the baseline

application.

For example, you might have three groups of data that you want to write to the

CompactFlash card. One group will be 250 bytes, one will be 3000 bytes, and

the last will be 10,000 bytes. The first two will not warrant any changes to the

baseline application, but the last will. You will need to expand three tag’s array

sizes.

Before writing to the CompactFlash card, calculate how big to make those

three arrays. Do not increase them to 10,000 bytes. Be sure to take into

consideration that of the 450 bytes, 8 bytes are checksum information, leaving

442 bytes for user data.

Step 1:

Actual_Bytes_to_RW = Bytes_to_RW + (TRN (Bytes_to_RW/442) * 8) + (If

the MOD (Bytes_to_RW/442) > 0 then 8 else 0)

Step 2:

450 [TRN(Actual_Bytes_to_RW/450) +(if the MOD (Actual_Bytes_to_RW)

> 0 then 1 else 0]

Topic Page

Modify the Application to Access More Data 49

Access 10,000 Bytes Example 50

Modify the Arrays 51

Modify the Data Element 51

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SanDisk CompactFlash 5000 Bedienerhandbuch Seite 49