SA9603C
6. Register Values
a.
The active and reactive energy measured per count, may be calculated by
applying the following formula:
V
I
*
K
Energy per Count
=
Watt seconds
Where
V
I
K
=
=
=
Rated Voltage
Rated Current
9281
for Active Energy
9281
2
*
for Reactive Energy
π
b.
c.
The mains frequency may be calculated as follows:
Crystal frequency
Register Value 8
*
Frequency =
To calculate the measured voltage, the following formula may be used:
V n
*
Vmeasured =
14000
t
*
Where
V
t
n
=
=
=
rated mains voltage
time difference between successive reads
difference in register values between
successive reads
7. Software Flow
The SA9603C is able to execute code written for the SA9103C without any
modifications. (Ensure that only bits of the serial command to the device is set that
need to be set.)
It is suggested that the DUMP command is used in cases where more than one
register is continuously read. The DUMP command initiates a serial transmission
of successive register values, starting with the specified register. The Dump
command does not reset the register values.
New software should be developed in such a way that registers are never resettled
and must allow for register overflow. Register overflow is easily taken into account
by software running on a controlling microcontroller. The software subtracts the
previous register value from the current register value in order to determine the
actual change in register value. Note that the mains frequency register value only
needs to be scaled, in order to calculate the true mains frequency in Hertz.
The SA9603C integrated circuit only transmits the register values after completion
of the current measurement cycle (8 mains periods maximum).
The delay of 8 mains periods may be calculated from the period value of the
frequencyreturnedbytheinitialread, andupdatedwitheachsubsequentfrequency
reading.
10/18
sa m e s
SAMES [ SAMES ]
