Address Syntax

The new Syntax has the following motivation

• Be more familiar with the TIA Syntax well known by S7 programmers
• Add Type Information to support all available TIA types
• "Type inference" to be not too verbose

Supported types

Syntax

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Datablocks

Addressing is different for non-primitive and primitive types.

The general syntax for addressing primitive values in a Datablock is

%DB{db-number}.DB{bit-length-code}{byte-offset}(.{bit-offset})?

...

db-number: number of datablock
bit-length-code:
	X - 1 bit
	B - 8 bit / 1 byte
	W - 16 bit / 2 byte
	D - 32 bit / 4 byte
byte-offset: offset in byte to start of data block
bit-offset: offset in bit to start of bit

For non primitive objects the (pointer?) notation from TIA is used which is

P#DB{db-number}.DBX{byte-offset}.{bit-offset}
Note, here, bit offset is not optional but usually always 0

Type identifier Postfix

Primitives

The parts are:

• data-area-code:
• bit-length-code:
• byte-offset
• bit-offset

...

Generally the TIA Syntax is used:

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Code Block
SINT USINT DINT LREAL LINT ULINTULINTtax

Strings

Please see https://support.industry.siemens.com/tf/WW/en/posts/string-data-type/51621?page=0&pageSize=10

A short description of the syntax and intern format is found here , or here https://support.industry.siemens.com/cs/mdm/109755202?c=94063831435&lc=en-WW

The following Syntax is valid and will be supported:

...

String Syntax

I did not find any suitable information on how Strings are adressed, except that simple characters can be adressed similar to a byte array.

As it makes no sense at all to use a "width" identifier for the String, I suggest to use the syntax

%DB{block-id}.{byte-offset}:STRING[length]
%DB{block-id}.{byte-offset}:STRING

where the second version refers to the first version with length 254.

This Synatx is motivated by the Syntax which TIA uses e.g. for markers ("%M4.1") where there is only one kind of datatype.

Examples for valid addresses

%DB3.DX4.1
%DB3.DX4.1:BOOL
%DB3.DB4:INT
%DB3.DB4:UINT
%DB3.DW4:REAL

Special Data Areas: Markers, Inputs, Outputs

They are always adressed bit-wise and the syntax is similar to TIA.

// Marker
%M1.0 // byte 1, bit 0
%I0.5 // byte 0, bit 5
%Q1.1 // byte 1, bit 1

Additional Documents

Programming Guideline

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https://support.industry.siemens.com/cs/mdm/109755202?c=69436189067&lc=en-WW

More Absolut addressing

https://euroec.by/assets/files/weintek/plc_connection_guide/Siemens_S7_1200_S7_1500_absolute_addressing_Ethernet.pdf

Cheat Sheet

Direct Adressing Overview

http://www.multiprojekt.pl/ftp/weintek_hmi/plc_connection_guide/Siemens_S7_1200_S7_1500_absolute_addressing_Ethernet.pdf