Partial Access to ANY_BIT Variables

According to IEC 61131-3, 3rd edition, the partial access to a specific bit, byte, word or double word of variables of the data type ANY_BIT is possible. The partial access to a variable is programmed by adding a dot (.) to the variable name followed by the optional '%' sign, the size prefix and an integer number (from 0 to max) for the address within the variable.

Examples

Note
Variables using partial access cannot be overwritten in online mode.

Syntax

The following table shows the syntax how to access a specific part of an ANY_BIT variable.

Bit-wise access to:

BYTE variable	<variable_name>%X0 to <variable_name>%X7
WORD variable	<variable_name>%X0 to <variable_name>%X15
DWORD variable	<variable_name>%X0 to <variable_name>%X31
LWORD variable	<variable_name>%X0 to <variable_name>%X63

Byte-wise access to:

WORD variable	<variable_name>%B0 to <variable_name>%B1
DWORD variable	<variable_name>%B0 to <variable_name>%B3
LWORD variable	<variable_name>%B0 to <variable_name>%B7

Word-wise access to:

DWORD variable	<variable_name>%W0 to <variable_name>%W1
LWORD variable	<variable_name>%W0 to <variable_name>%W3

DWord-wise access to:

LWORD variable

<variable_name>%D0 to <variable_name>%D1

Intellisense for partial access to ANY_BIT variable

The Intellisense function in the text and graphic editors supports the specification of a specific part of an ANY_BIT variable.
Entering the variable name of the ANY_BIT variable followed by a dot opens the selection box with all size prefixes allowed for the entered variable.

Text editor example

Graphic editor example