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3.4.6 Examples
3.4.6.1 Example of "Function Code" 3
Reading an error memory entry. Since the Modbus addresses of the
parameters of an error memory entry are contiguous (ascending
order), a single Modbus request is sufficient.
Parameters _ERR_number (15362), _ERR_class (15364),
_ERR_time (15366) and _ERR_qual (15368).
Modbus request Structure of the Modbus request:
Field Bytes Value Meaning
Function Code 1 3 Read Multiple Registers
Starting Address 2 15362 (3C02
h
) Address of the first parameter to be read
Quantity Of Regis-
ters
2 8 Number of the 16 bit values to be read = 8
Modbus response Structure of the positive Modbus response:
Field Bytes Value Meaning
Function Code 1 3 Read Multiple Registers
Byte Count 1 16 Number of bytes: 8 bytes of data
Registers Value 16 32 bit value
32 bit value
32 bit value
32 bit value
_ERR_number, 15362 (error number)
_ERR_class, 15364 (error class)
_ERR_time, 15366 (error time)
_ERR_qual, 15368 (error qualifier)
3.4.6.2 Example of "Function Code" 16
Writing of the software limit switches. Since these parameters also
have consecutive addresses, a single Modbus request is sufficient:
Parameters MON_swLimP (1544) and MON_swLimN (1546).
Modbus request Structure of the Modbus request:
Field Bytes Value Meaning
Function Code 1 16 Write Multiple Registers
Starting Address 2 1544 (608
h
) Address of the first parameter to be written
Quantity Of Regis-
ters
2 4 Number of parameters = 4 (8 bytes of data)
Byte Count 1 8 Number of bytes: 8 bytes of data
Registers Value 8 32 bit value
32 bit value
MON_swLimP, 1544
MON_swLimN, 1546
Modbus response Structure of the positive Modbus response:
Field Bytes Value Meaning
Function Code 1 16 Write Multiple Registers
Starting Address 2 1544 (608
h
) Address of the parameter
Quantity Of Regis-
ters
2 4 Number of parameters = 4 (8 bytes of data)
LXM32M
3 Basics
Modbus-TCP module 33
0198441113843, V1.01, 01.2012