SA9110A
Offset Adjustment
The precision of this device does not require any offset adjustment for Class 1
metering. This facility has been provided to compensate for poor PCB layout or
circumstances requiring precision well beyond a Class 1 rating.
The offset of the device may be adjusted by programming a different offset into the
device during calibration. To calaculate the offset the following procedure should
be followed:
Measure the linearity error at the current where offset correction is needed.
I
M
* E
RR
K
O
=
I
R
* 6 * 10
-6
Where
I
M
= Measured current on the current sensor
I
R
= Rated current on the current sensor
E
RR
= Error ratio between the device and the Wh standard
K
O
= Offset constant (-127 ... 127)
Note that K
O
must be programmed as a integer value.
Meter/Manufacturers Identification Data
A total of eleven 4 bit words are available to store relevant data such as the meter
and manufacturer identification codes. For the optical interface protocol, the 4-bit
words are converted to 8-bit words (ASCII-format).
Writing to RAM
The memory is configured as ten 32 bit words. The programming data must be
written to the device as a bitstream containing a total of 320 bits. ROM-locations
will not be overwritten.
Word
number
1
1
2
2
3
3
4
4
5
Bit
number
31..28
27..0
31..28
27..0
31..28
27..0
31..28
27..0
31..28
Function
Sign of Register 1
Register 1
Sign of Register 2
Register 2
Sign of Register 3
Register 3
Sign of Register 4
Register 4
Sign of Register
'Total'
Description
A '1' indicates a negative register value
Contents of register 1 in binary coded decimal
A '1' indicates a negative register value
Contents of register 2 in binary coded decimal
A '1' indicates a negative register value
Contents of register 3 in binary coded decimal
A '1' indicates a negative register value
Contents of register 4 in binary coded decimal
A '1' indicates a negative register value
10/18
sames
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