GE PQM II, Instruction Manual

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CHAPTER 7: APPLICATIONS
PQMII POWER QUALITY METER – INSTRUCTION MANUAL 7–17
• Register number of Next Record to Write : A pointer to the register containing the
last record in the Data Log.
• Log Pointer to First Item of Record After Last : A pointer to the next record to be
written into the Data Log.
• Log Status: The current status of the Data Log ; i.e.: Running or Stopped.
• Log Records Used : The number of records written into the Data Log.
• Log Time Remaining Until Next Reading : A counter showing how much time
remains until the next record is to be written into the Data Log.
7.6.2 Modes of Operation
The Data Logger has 2 modes of operation, Run to Fill and Circulate. In the Run to Fill
mode, the Data Log will stop writing records into the memory structure when there is not
enough memory to add another record. Depending on the size of each record, the Data
Log may not necessarily use the entire 196,608 bytes of storage available. In the Circulate
mode, the Data Log will continue to write new Records into the Log beyond the last
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.
7.6.3 Accessing Data Log Information
The Data Log can be accessed using the EnerVista PQMII Setup Software or manually via
the serial port. Access via the EnerVista PQMII Setup Software is described in
Data Logger
on page 4–12. Access manually via the serial port as follows:
1. Set the Block of data you wish to access at 1268h in the PQMII Memory Map.
2. 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 spreadsheet for analysis. 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 1535. This requires 1536 reads of 128 bytes each. The data can then be
interpreted based upon the parameter configuration.
7.6.4 Interpreting Data Log Information
Using two (2) Data Logs in the “Run to Fill” mode, the Data Log is configured as shown
below.