Siemens S7 PLC Data Address Format

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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 Format 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
E refers to Eingang, the German word for Input
Output Qnnnn
A refers to Ausgabe, the German word for Output
Flags Mnnnn
V Memory Vnnnn V is an alias for Data Block 1.
Data Block 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 Format is used in these contexts:

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 on the Browse button Browse button at the right side of the DataAddress field:

Siemens S7 Memory Address Editor

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.


For the meaning of terms used in Fernhill SCADA.