GE PQMII - Page 188

7–18 PQMII POWER QUALITY METER – INSTRUCTION MANUAL
CHAPTER 7: APPLICATIONS
Blocks 0 and 1 are reserved for Data Logger Data Interval information. Block 2 contains
header information for both Data Logs. The first 32 registers of Block 2 are reserved for
Data Log 1 header information, and the remaining 32 registers are reserved for Data Log 2
header information. The first register of Data Log information resides at Register 0 of Block
3. This leaves 196224 bytes of data storage.
FIGURE 7–3: Data Log Configuration
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 0AB2
and 0AB3 in the memory map. The Log Start Address consists of the block number (0AB2)
and the register number (0AB3) which represents the location of the first record within the
Data Log memory structure. 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 log pointers contain a value from 0 to 196607 representing a byte within the data Log
memory structure. Add 1 to this number and then divide this number by 64 (number of
registers in a Block). Then divide this number by 2 (number of bytes in a register), and
truncate the remainder of 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
pointer: “Log 2 Pointer to First Item of First Record” was 34235, then the Block and Register
numbers containing 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. These calculations can
be avoided by using the pre-calculated values for Block Number and Record number
located just prior to the pointer (0AB7 and 0AB8).
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 26 bytes, and there were 28 bytes of memory left in the memory
structure, the Data Logger will not use those last 28 bytes, regardless of the mode of
operation. The Data Logger uses the following formula to determine the total record space
available:
BLOCK 3
FIRST RECORD OF DATA
LOG 1 HEADER
RESERVED
RESERVED
LOG 2 HEADER
BLOCK 1534
BLOCK 1535
REGISTER0
REGISTER0
REGISTER0
REGISTER0
REGISTER32 REGISTER33
REGISTER63
REGISTER63
REGISTER63
REGISTER63
BLOCK 2
BLOCK 1
BLOCK 0
REGISTER0
REGISTER0
REGISTER63
REGISTER63