GE Power Quality Meter Series Instruction Manual page 263

APPENDIX A
available Record space. The Log will overwrite the first Record after the Header and continue to overwrite the
Records to follow until the user wishes to stop logging data. The Log will act as a rolling window of data in time,
going back in time as far as the amount of records times the Log Time Interval will allow in the total space of
memory available.
a) ACCESSING THE DATA LOG INFORMATION
The Data Log can be accessed in two ways: using PQMPC via the serial port. Access via PQMPC is as
described in Chapter 6: SOFTWARE. Access is manually via the serial port as follows:
• Set the Block of data you wish to access at 1268h in the PQM Memory Map
• Read the required amount of data from the 64 Registers in the Block
Accessing the Data Log in this manner assumes that the user knows which Block they wish to access, and
knows the size of each Record based upon the parameters they have selected to log.
The easiest way to access the data in the Data Log is to read the entire log and export this data into a spread-
sheet for analysis (this is the method incorporated by PQMPC). This requires defining the Block to be read,
starting at Block 0, and reading all 128 bytes of data in each of the 64 Registers within the Block. You would
then define Blocks 1,2,3 etc. and repeat the reading of the 64 Registers for each block, until Block 511. This
requires 512 reads of 128 bytes each. The data can then be interpreted based upon the parameter configura-
tion.
b) INTERPRETING THE DATA LOG INFORMATION
Using 2 Data Logs in the Run to Fill mode, the Data Log is configured as follows:
BLOCK 3
Blocks 0 and 1 are reserved for Data Logger Data Interval information. Block 2 contains the Header informa-
tion for both Data Logs. The first 32 registers of Block 2 are reserved for Data Log 1 Header Information, and
the remaining 32 registers of Block 2 are reserved for Data Log 2 Header Information. The first register of Data
Log information resides at Register 1 of Block 3. This leaves 65152 bytes of storage for data.
The location of the first Record in Log 2 will depend upon the Log configuration. Its location is determined by
reading the Log 2 Header value for Log Start Address at location 0AAEh in the memory map and performing a
calculation. The Log Start Address is a value from 0 to 65535 representing the first byte of the first Record
within the Data Log memory structure. Add 1 to this number and then divide this number by 64 (number of
Records in a Block). Then divide this number by 2 (number of bytes in a record), and truncate the remainder of
GE Power Management
RESERVED
RESERVED
LOG 1 HEADER
FIRST RECORD OF DATA
Figure A–2: DATA LOG CONFIGURATION
PQM Power Quality Meter
A.1 PQM APPLICATION NOTES
LOG 2 HEADER
32 33
A
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