6X Registers; Function Code 20 (Read General Reference) And 21 (Write General Reference) - ABB TPU2000 Technical Manual

TPU2000/2000R Modbus/Modbus Plus/ Modbus TCP/IP Automation Guide

6X Registers

General Relay settings are available for viewing via the TPU2000/TPU2000R front panel interface. All parameters
accessible through the front panel, ECP or WinECP are accessible through the Modbus 6X registers.
A protective relay may have thousands of parameters stored in its configuration. The Modbus/Modbus Plus
capable 984-680 programmable logic controllers (and earlier models) have historically only defined up to 1890 or
1920 registers for access within its products.
programmable logic controllers allowed defined up to 10,000 4X registers. Even with this improvement, this
amount of registers was still too limited to store the vast amount of information available for retrieval and storage
within a Modbus node (or protective relay for that matter).
Modbus protocol included a standard 6X register type. The protocol defines this memory as extended memory.
Modbus 6X memory is available in groups of 10,000 registers. Up to 10 groups may be defined within a node.
Each group is referenced in the Modbus protocol as a file.
It is a standard ABB practice to store any configuration settings in 6X register memory. The TPU2000/TPU2000R
has all its parameters stored in File 0 of the 6X memory definition (Files being defined from 0 through 9).
Generally, all configurable functions available through ECP or WinECP configuration package may be configured
via the 6X Modbus registers. However, ECP or WinECP configures the IED through the Standard Ten Byte
protocol. ECP or WinECP configuration through the Modbus or Modbus Plus network is not possible at this time.
The available configuration parameter functions via the 6X registers are:
Programmable Logic Input Configuration
Programmable Logic Output Configuration
Primary Relay Settings
Alt 1 Relay Settings
Alt 2 Relay Settings
Relay Configuration Settings
Counter Settings
Alarm Settings
Real Time Clock Configuration
ULO Connection Settings and Name Assignment
Forced Logical Input Configuration and Name Assignment
Modbus Plus Global Data Configuration
User Definable Register Configuration
Password Security Mask Control Configuration
Oscillographics Control and Status
Each topic is covered in the sections following this discussion.

Function Code 20 (Read General Reference) and 21 (Write General Reference)

Modbus Protocol defines two commands 20 and 21 to read and write the registers within the 6X register groups
(or blocks). Figure 5-64 illustrates the frame sequence of Function 20 and Figure 5-65 illustrates the frame
sequence of Function 21.
Later definitions of the Modbus/Modbus Plus Protocol and
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