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LeveLine
®
Instruction Manual
10401-01026 Rev D
6.14.3. Read Input Registers
This command reads one or more Modbus input registers and has the format:
Field
Size
Content
<a>
1 byte
Slave address
<function-code>
1 byte
0x04
<start-address>
2 bytes
Base address of the block of registers to be read
(0x0000-0xFFFF)
<nr-registers>
2 bytes
The number of registers to be read (0x0001-
0x007D)
<crc>
2 bytes
CRC
NOTE: The address in the <start-address> field is the register number – 1.
The LeveLine
®
will send a response with the format:
Field
Size
Content
<a>
1 byte
Slave address
<function-code> 1 byte
0x04
<values-size>
1 byte
Size in bytes of <values> field (equal to 2 x <nr-
registers>)
<values>
<values-
size> bytes
Block of data containing the values of the requested
registers, 2 bytes per register, in order of increasing
address from <start-address> onwards
<crc>
2 bytes
CRC
6.14.4. Write Holding Register
This command writes a value to a single Modbus holding register and has the format:
Field
Size
Content
<a>
1 byte
Slave address
<function-code>
1 byte
0x06
<address>
2 bytes
Address of the register to be written (0x0000-
0xFFFF)
<value>
2 bytes
Value to be written to the register (0x0000-
0xFFFF)
<crc>
2 bytes
CRC
NOTE: The address in the <start-address> field is the register number – 1.
The LeveLine
®
will set the register to the specified value and echo the received command
packet as its response.
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®
Ltd.
www.aquaread.com
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