1MDU07205-YN rev. F
REF601 CEI
User’s manual
78
7.4.1 Function Code: 03 (Read Relay Settings)
This function code is used to read the parameter settings of the relay unit. The
request packet specifi es the starting register address and the number of registers.
In the packet, registers are addressed starting at zero. Therefore registers numbered
1-15 are addressed as 0-14.
The register data in the response message are packed as two bytes per register, with
the binary contents right justifi ed within each byte. For each register, the fi rst byte
contains the high order bits and the second contains the low order bits.
Slave
Address
Function
Code
Starting
Address
High
Starting
Address
Low
Quantity
of
registers
High
Quantity
of
registers
Low
CRC CRC
01 03 00 01 00 05 CRC CRC
Request
Example: Read relay settings 1 to 5, from slave at address 01.
Slave
Address
Function
Code
Byte
Count
Data1
Hi
Data1
Lo
Data5
Lo
Data5
Lo
CRC CRC
01 03 0 Ah 00 05 00 56 CRC CRC
Response message format for function code 03
In the response the relay settings is shown as data bytes. The byte count provides
the number of bytes that will follow.
The register mapping of relay settings to addresses for IEC and CEI 0-16 models is
shown in table-3 and table-4 respectively.
The same function code is also used to read the relay confi guration parameters. The
address range to read the confi guration parameters is 0x20 – 0x26, and maximum
number of registers is 7. The mapping of address to confi guration parameter read
is shown in table 5
Serial Communication
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