APPENDIX A: APPLICATION NOTES READING LONG INTEGERS FROM MEMORY MAP
PQM POWER QUALITY METER – INSTRUCTION MANUAL A–21
The most significant bit of the High Order register is not set, therefore the DATA VALUE is as
calculated. Applying the Units & Scale parameters to the DATA VALUE, we multiply the DATA
VALUE by 0.01 kW. Therefore the resultant value of 3 Phase Real Power as read from the
memory map is 51911.21 kW.
3. Reading a negative 3 Phase Real Power actual value from the PQM:
4. Following the method described above:
DATA VALUE = (FF3A × 2
16
) + EA7Bhexadecimal
= (65338 × 2
16
) + 60027converted to decimal
= 4282051195decimal
5. The most significant bit of the High Order register is set, therefore the DATA VALUE is
calculated as:
DATA VALUE = DATA VALUE – 2
32
= 4282051195 – 4294967296
= –12916101
Applying the Units & Scale parameters to the DATA VALUE, we multiply the DATA VALUE by
0.01 kW. Therefore the resultant value of 3 Phase Real Power as read from the memory
map is –129161.01 kW.
REGISTER ACTUAL VALUE
(hex)
DESCRIPTION UNITS & SCALE FORMAT
02F0
02F1
FF3A
EA7B
3 Phase Real Power (high)
3 Phase Real Power (low)
0.01 x kW F4
Courtesy of NationalSwitchgear.com
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