SA9103C
The register access codes which can be written to the SA9103C via the serial
communications port are shown in the table below.
REGISTER
ACTIVE
RE-ACTIVE
VOLTAGE
FREQUENCY
Data on SOUT
8
9
10
11
12
13
14
15
0
1
2
3
4
5
6
7
READ
$01
$81
$C1
$41
RESET
$02
$82
$C2
-
READ-RESET
$03
$83
$C3
-
FIRST BYTE
DR-00835
SECOND BYTE
From the two bytes of data output by the device, the value for the register can
be derived as shown:
Register value =
(First Byte * 256) + Second Byte
The most significant bit of the 16 bit energy register (active or reactive) is an
indication of the direction of the energy flow (0 = positive, 1 = negative).
6.
Register Values
a.
The active and reactive energy measured per count, may be calculated by
applying the following formula:
V*I
Energy per Count
=
K Watt seconds
Where
V
I
K
=
=
=
Rated Voltage
Rated Current
9281
for Active Energy
9281 * 2 for Reactive Energy
π
b.
The mains frequency may be calculated as follows:
Crystal frequency
Frequency =
Register Value * 8
To calculate the measured voltage, the following formula may be used:
V*n
Vmeasured = 14000 t
*
Where
V
=
rated voltage
t
=
time difference between successive reads
n
=
difference in register values between
successive reads
sames
c.
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SAMES [ SAMES ]
