Description :
o For Data logging Flash Memory is used so data will be fetched in the form of multiple records.
Flash page size is of 256 bytes.
o The record length is based on Channel number for log selection
o So in from below equation we can get how many records we can get from 1 page i.e.
Records per page = (Integer) (256 / Total Bytes in 1 record)
o Example for Fetching data :
Example 1 :
If we have selected 8 channels for periodic data logging so that
Total Bytes in 1 record = 12 + (2 * 8) = 28
Record Per page = 256 / 28 = 9(Odd Number)
So in this case for fetching data, follow below procedure:
1. Write Hold Data = 1
2. Write Fetch Data = 1
3. Data for first 4 records are loaded into data registers
4. Write Fetch Data = 1
5. Data for record number 5 to 9 will be loaded into data registers
6. Write Fetch data = 1
7. Data for record number 10 to 13 will be loaded into data registers
8. Write Fetch data = 1
9. Data for record number 14 to 18 will be loaded into data registers
10. So in same manner data registers will be filled with 4 records first and then 5 records.
11. After all data fetch Write Hold Data = 0.
Example 2 :
If we have selected 24 channels for periodic data logging so that
Total Bytes in 1 record = 12 + (2 * 24) = 60
Record Per page = 256 / 60 = 4(Even Number)
So in this case for fetching data follow below procedure:
1. Write Hold Data = 1
2. Write Fetch Data = 1
3. Data for first 2 records are loaded into data registers
4. Write Fetch Data = 1
5. Data for record number 3 - 4 will be loaded into data registers
6. Write Fetch data = 1
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