4 function 16: preset multiple registers, Rtu framing, Function 16: preset multiple registers – RLE LD2000 User Manual

Page 58: Table 5.11, Preset multiple registers packet structure, Table 5.12, Response sample

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Modbus Communication

5.2.4 Function 16: Preset Multiple Registers

To set multiple LD2000 parameter values, the master must send a Preset Multiple Registers

request packet. The Preset Multiple Register request packet specifies a starting register, the

number of registers, a byte count and the data to write to the registers. The register is

numbered from zero (40001 = zero, 40002 = one, etc).

5.3. RTU

Framing

The example below shows a typical Query/Response from an LD2000 module.

Slave address 2 responds to Function Code 4 with six bytes of hexadecimal data and ends with

CRC16 checksum.

Register Values:

40001 = 0000 (hex)

40002 = 0000 (hex)

40003 = 0001 (hex)

Table 5.11 Preset Multiple Registers Packet Structure

Preset Registers Request Packet

Preset Registers Response Packet

Slave Address (1 byte)

16 (Function code) (1 byte)

Start Register (2 bytes)

# of registers to write (2 bytes)

# of registers (2 bytes)

Byte Count (1 byte)

Crc Checksum (2 bytes)

Data (2 bytes)

…

Crc Checksum (2 bytes)

Table 5.12 Response Sample

Slave

Address

Function

Code

Count Bytes

of Data

Register

Data

Msb

Lsb

Register

Data

Msb

Lsb

Register

Data

Msb

Lsb

CRC

“Lsb”

CRC

126

“Msb”

00 00

00 01