GE Power Quality Meter Series, Инструкция по эксплуатации

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A-14 PQM Power Quality Meter GE Power Management
A.1 PQM APPLICATION NOTES APPENDIX A
A
the division to determine the Block number. Multiplying the remainder of the division by 64 will determine the
Register number. For example, if the Log Start Address was 34235, then the Block and Register numbers con-
taining the first record of Log 2 are:
Block Number = (34235 + 1) / 64 / 2 = 267.46875
Therefore, Block Number 267 contains the starting record.
Record Number = 0.46875
×
64 = 30
Therefore, Register Number 30 contains the first byte of Log 2 data
This location will always be the starting address for Data Log 2 for the given configuration. Adding or deleting
parameters to the configuration will change the Log 2 Starting Address.
The Data Logs will use the maximum amount of memory available, minus a 1 record buffer, based upon the
user configuration. For Example, if the Record Size for a given configuration was 24 bytes, and there were 40
bytes of memory left in the memory structure, the Data Logger will not use that last 40 bytes, regardless of the
mode of operation. The Data Logger uses the following formula to determine the total record space available…
Total Space = (65152 / Record Size) – 1
As in the example, the total space calculated would be 65152 / 24 – 1 = 2713.67. This equates to 2713 records
with 40 bytes of unused memory at the end of Block 511. The total amount of space used in the structure can
also be found in the Log Header in the Log Total Records field.
When the Data Log is configured for Circulate mode of operation, the memory structure is the same as for
Run to Fill mode. To read the Log data, you must use the Log Starting Address, Log Record Size, and Log
Total Records information from each of the Log Headers. The Log Starting Address for Log 2 can be deter-
mined as shown in the previous calculation for Run to Fill mode. The total space occupied in the memory struc-
ture by either log is determined by multiplying the Log Total Records by the Log Record Size and adding this
value to the Log Starting Address. It is important to note that the Log Starting Address is always referenced to
the first Register of Block 0, or the first byte of the Data Log memory structure.
Once you have separated the Data Log data from the Headers, you will then need to interpret the data into a
structured format. Each Record is comprised of user-defined parameters. These parameters are implemented
into the user-defined structure in a specific order based upon selection into either, or both, Data Log(s).
Address 1270h in the PQM Memory Map is the Holding Register for the first available parameter for use by the
Data Logs. The Data Logs will place the user-selected parameters into their respective Record structures
based upon their respective order in the PQM Memory Map. For example, if Positive kWh, Frequency and Cur-
rent Unbalance were selected to be measured parameters, they would be placed into the Record structure in
the following order:
Unbalance 2 bytes (16 bit value)
Frequency 2 bytes (16 bit value)
Positive kWh 4 bytes (32 bit value)
The DATA LOG PARAMETERS table on the following page illustrates the order of parameters and their size.
Therefore, the Record size would be 8 bytes. To put a time value associated with each Record, you must read
the Log Time and Date from the Header. This is the time of the last Record in the Log. To time stamp the first
Record used, multiply the Log Time Interval by the Log Records Used and subtract this number from the time
associated with the last Record. To determine the time associated with any Record, add the Log Time Interval
times the Record to be read to the time associated with the first Record in the Log.
For example:
Log Time Interval: 3600
Log Time - Hours/Minutes: 02 30
Log Time - Seconds:
30300