Editing Modbus protokoll rs485 (section)

===  DDS578R Energy Meter ===

MODBUS-RTU communication protocol Description:

1.the data format: <br>
Address + function code + data + CRC check code<br>
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2.the register type<br>
This meter uses two types of registers, individually addressed<br>
The first is the data register, read-only, using the command code 0x04 to read.<br>
The second category is the parameter register, readable and writable, using the command code 0x03<br>
read, write parameters using 0x10<br>
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3.the data format<br>
Float type data: Read the internal data within the meter in line with IEEE-754 standardv
floating-point number, data format is 32-bit 4-byte single-precision floating-point data format.<br>
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4、Data register list<br>

{| class="wikitable"
! colspan="4"| Data register address !! colspan="6"| Register Description
|-
| adr || fc  || highByte || lowByte || Description     || unit ||  Format        || Mode
|-
| xx  || 03  || 00        ||    00   || A phase voltage || V    || Floating point || Read-only
|-
| xx  || 03  || 00        || 02      || B phase voltage || V    || Floating point || Read-only
|-
| xx  || 03  || 00        || 04      || C phase voltage || V    || Floating point || Read-only
|-
| xx  || 03  || 00        || 08      || A line current  || A    || Floating point || Read-only
|-
| xx  || 03  || 00        || 0A      || B line current  || A    || Floating point || Read-only
|-
| xx  || 03  || 00        || 0C      || C line current  || A    || Floating point || Read-only
|-
| xx  || 03  || 00        || 10      || Total active power || KWh || Floating point || Read-only
|-
| xx  || 03  || 00        || 12      || A phase active power || KWh || Floating point || Read-only
|-
| xx  || 03  || 00        || 14      || B phase active power || KWh || Floating point || Read-only
|-
| xx  || 03  || 00        || 16      || C phase active power || KWh || Floating point || Read-only
|-
| xx  || 03  || 00        || 18      || Total reactive power || KWh || Floating point || Read-only
|-
| xx  || 03  || 00        || 1A      || A phase reactive power || Var || Floating point || Read-only
|-
| xx  || 03  || 00        || 1C      || B phase areactive power || Var || Floating point || Read-only
|-
| xx  || 03  || 00        || 1E      || C phase reactive power || Var || Floating point || Read-only
|-
| xx  || 03  || 00        || 2A      || A phase power factor ||  || Floating point || Read-only
|-
| xx  || 03  || 00        || 2E      || B phase power factor ||  || Floating point || Read-only
|-
| xx  || 03  || 00        || 2C      || C phase power factor ||  || Floating point || Read-only
|-
| xx  || 03  || 00        || 36      || frequency || frequency  || Floating point || Read-only
|-
| xx  || 03  || 01        || 00      || Total active electricity power  || KWh  || Floating point || Read-only
|-
| xx  || 03  || 04        || 00      || Total reactive electricity power|| KWh || Floating point || Read-only
|-
|}


The second category register (parameter register) read and operate read the meter Address:<br>

(HEX):01 03 00 08 00 02 45 C9<br>

Date descriptions 

{| class="wikitable"
|-
! Data      !! Detailed description
|-
| 0x01      || Instrument address ( adr )
|-
| 0x03      || Function code, read parameter register ( fc )
|-
| 0x00 0x08 || reading the data from the 00 08 meter internal register address
|-
| 0x00 0x02 || Read data length for two words( four bytes )of data
|-
| 0x45 0xC9 || CRC checksum data for the front, where the high front and low in the post
|-
|}

Returns Data (HEX) 01 04 03 40 00 00 00 EF F3

{| class="wikitable"
|-
! Data      !! Detailed description
|-
| 0x01      || Instrument address
|-
| 0x03      || Function code, read parameter register
|-
| 0x04      || Returned data length is 4 bytes of data length
|-
| 0x40 0x00 0x00 0x00 || TUSB To RS485 Converterhe data returned as a 4-byte data type float
|-
| 0xEF 0xF3 || CRC checksum data for the front, where the high front and low in the post
|-
|}
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