Mailbox addressing – Rockwell Automation 2711P Creating Modbus Applications User Manual

Page 67

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Publication 2711P-UM002B-EN-P - March 2007

Modbus/TCP Address Definitions 67

Mailbox Addressing

Default types are shown in bold.

Arrays

Arrays are also supported for the holding register addresses. The
syntax for declaring an array (using decimal addressing) is 4xxxx[cols]
with assumed row count of 1 and 4xxxx[rows][cols].

For Word, Short and BCD arrays, the base address + (rows * cols)
cannot exceed 65536.

For Float, DWord, Long and Long BCD arrays, the base address +
(rows * cols * 2) cannot exceed 65535.

For all arrays, the total number of registers being requested cannot
exceed the holding register block size that was specified for this
device.

Mailbox Addressing

Decimal Addressing

Hexadecimal Addressing

Type

Word, Short, BCD

Format

4xxxxx

H4yyyyy

Security

Read/Write

Range

1 - 65536

1 - 10000

Type

Boolean

Format

4xxxxx.bb

H4yyyyy.c

Security

Read/Write

Range

xxxxx.0 - xxxxx.15

yyyyy.0 - yyyyy.F

Type

Float, DWord, Long, LBCD

Format

4xxxxx

H4yyyy

Security

Read/Write

Range

1 - 65535

1 - FFFF

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