SI-Ethernet User Guide 137
Issue: 3
Safety
information
Introduction
Mechanical
installation
Electrical
installation
Getting started Parameters
Key features
and Protocols
PC Tools
Applications
Security Diagnostics
Glossary of
terms
Index
Figure 7-2 Data type selection
If 32-bit data type is selected then this effectively adds 16384 (0x4000) to the start register
address.
e.g. For drive parameter Pr 01.021 in standard addressing mode, the start register value is 16384
+ 120 = 16504 (0x4078)
7.2.5 Supported Modbus function codes
The following table details the supported Modbus function codes.
Table 7-4 Supported Modbus function codes
7.2.6 Register addressing
The Modbus register address is 16 bits in size, of which the upper two bits are used for data type
selection leaving 14 bits to represent the parameter address, taking into account the slave
increments the address value by 1, this results in a theoretical maximum parameter address of
163.84 (limited to 162.99 in software) when the default standard addressing mode (see Modbus
Register Addressing Mode (S.15.013)) is used.
To access a parameter number above 99 then the modified addressing mode must be used (see
Modbus Register Addressing Mode (S.15.013)), this will allow access to parameter numbers up to
255 but also limit the maximum menu number to 63.
The Modbus slave device increments the register address by 1 before processing the command,
this effectively prevents access to parameter Pr 00.000 in the drive or option module.
The table below shows how the start register address is calculated for both addressing modes.
Function Code
Description
Decimal Hex (0x)
3 03 Read multiple 16-bit registers
6 06 Write single 16-bit register
16 10 Write multiple 16-bit registers
23 17 Read and write multiple 16-bit registers
A reset is not required to activate the change, the addressing mode is effectively made
active immediately on changing.
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