Siemens S7 PLC Data Address

Introduction

Data in Siemens S7 PLC Devices is stored different locations depending on the intended use of the data. For example, there are separate locations for Inputs, Outputs, Data Blocks and so on.

The Siemens S7 PLC Data Address is a string that defines the location of data in a Siemens S7 PLC Device. It consists of device type letters, followed by one or two decimal numbers:

Device Type	Format	Notes
Input	Innnn Ennnn	E refers to Eingang, the German word for Input
Output	Qnnnn Annnn	A refers to Ausgabe, the German word for Output
Flags	Mnnnn Fnnnn
V Memory	Vnnnn	V is an alias for Data Block 1.
Data Block	DBbb.nnnn DBbb,nnnn	bb is the data block number. Either a comma (,) or period (.) can be used between the data block number and offset.

Note: The numbers in Siemens S7 PLC Data Addresses are zero-based.

Siemens S7 PLC Data Address examples:

Address	Description
I0	The first byte of inputs.
Q124	Output byte 124. The first output of the integrated I/O of an S7-300 PLC with built-in I/O, for example the CPU313C.
V100	In S7-300/400 PLC Devices byte 100 in Data Block 1. In S7-200 PLC Devices byte 100 of V Memory
DB01.0	In S7-300/400 PLC Devices the first byte in Data Block 1. In S7-200 PLC Devices the first byte of V Memory.

Where Used

The Siemens S7 PLC Data Address is used in these contexts:

In the IOItemName property of an I/O Analog Data Point Tag when the tag is associated with a Siemens S7 PLC.
In the IOItemName property of a I/O Digital Data Point Tag when the tag is associated with a Siemens S7 PLC.
In the IOItemName property of a I/O Double Word Data Point Tag when the tag is associated with a Siemens S7 PLC.
In the IOItemName property of a I/O String Data Point Tag when the tag is associated with a Siemens S7 PLC.
In the IOItemName property of a I/O Word Data Point Tag when the tag is associated with a Siemens S7 PLC.
In the MemoryAddress property of a Siemens S7 Memory Block.
In the DataAddress parameter of the DirectWriteBit Tag Command when used with a Siemens S7 PLC.
In the DataAddress parameter of the DirectWriteByte Tag Command when used with a Siemens S7 PLC.

Data Address Editor

The Data Address Editor provides a convenient tool to build Siemens S7 Data Address strings.

To open the Data Address Editor, click the Browse button of the IOItemName or MemoryAddress property:

Further Information

Siemens S7 Memory Block Tag

To learn about Siemens S7 Memory Block Tags.

Siemens S7 Driver

For an overview of the Siemens S7 Driver.

Glossary

For the meaning of terms used in Fernhill SCADA.