SA9110A

10/18

sames

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.

K

O

=

I

M

I

R

* 6 * 10

-6

Where

I

M

= Measured current on the current sensor

I

R

= Rated current on the current sensor

E

Error ratio between the device and the Wh standard

K

O

= Offset constant (-127 ... 127)

Note that K

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

Bit

Function

Description

number number

1

31..28

Sign of Register 1

A '1' indicates a negative register value

1

27..0

Register 1

Contents of register 1 in binary coded decimal

2

31..28

Sign of Register 2

A '1' indicates a negative register value

2

27..0

Register 2

Contents of register 2 in binary coded decimal

3

31..28

Sign of Register 3

A '1' indicates a negative register value

3

27..0

Register 3

Contents of register 3 in binary coded decimal

4

31..28

Sign of Register 4

A '1' indicates a negative register value

4

27..0

Register 4

Contents of register 4 in binary coded decimal

5

31..28

Sign of Register

A '1' indicates a negative register value

'Total'