DOCA0091EN-08

### Readout Example of a Modbus Register

The table below shows how to read the rms current on phase 1 (I1) in register 12016.

• The address of register 12016 equals 12016 - 1 = 12015 = 0x2EEF.

• The Modbus address of the Modbus slave is 47 = 0x2F.

Request from the Master

Response from the Slave

Field Name

Example

Field Name

Example

0x2F

0x2F

Function code

0x03

Function code

0x03

0x2E

Data length in bytes

0x02

0xEF

Register value (MSB)

0x02

Number of registers (MSB)

0x00

Register value (LSB)

0x2B

Number of registers (LSB)

0x01

CRC (MSB)

0xXX

CRC (MSB)

0xXX

CRC (LSB)

0xXX

CRC (LSB)

0xXX

The content of register 12016 (address 0x2EEF) is 0x022B = 555.

The rms current on phase 1 (I1) is thus 555 A.

### Readout Example of the Table of Legacy Dataset Common Registers

The table below shows how to read the table of legacy dataset common registers. This table starts at register 12000 and consists of 113 registers.

• The address of register 12000 = 0x2EDF.

• The table length is 113 registers = 0x71.

• The number of bytes is 113x2 = 226 bytes = 0xE2.

• The Modbus address of the slave is 47 = 0x2F.

Request from the Master

Response from the Slave

Field Name

Example

Field Name

Example

0x2F

0x2F

Function code

0x03

Function code

0x03

0x2E

Data length in bytes

0xE2

0xDF

Value of register 12000 (MSB)

0xXX

Number of registers (MSB)

0x00

Value of register 12000 (LSB)

0xXX

Number of registers (LSB)

0x71

Value of register 12001 (MSB)

0xXX

CRC (MSB)

0xXX

Value of register 12001 (LSB)

0xXX

CRC (LSB)

0xXX

0xXX

0xXX

Value of register 12112 (MSB)

0xXX

Value of register 12112 (LSB)

0xXX

CRC (MSB)

0xXX

CRC (LSB)

0xXX