Siemens 020-011 Benutzerhandbuch
Industry Sector, IA&DT
SCE Training Curriculum
Page 19 of 79
To be used only in Educational and R&D Facilities
TIA Portal Module 020-011, Edition 04/2014
Unrestricted / © Siemens AG 2014. All Rights Reserved
SCE_EN _020-011_R1404_Startup Programming with SIMATIC S7-1500
5.5
How does the SIMATIC S7-1500 address individual input/output signals?
Specifying a certain input or output within the program is called 'addressing‘.
The inputs and outputs of the PLCs are usually combined into groups of eight for digital input and digital
output modules. This group of eight is called byte. Each such group is assigned a number as the so-
called byte address.
To address a single input or output within a byte, each byte is divided into individual bits. These are
numbered starting with Bit 0 to Bit 7. This is how we get the bit address.
The PLC shown here now has a signal module with the input bytes 0 to 3 as well as the output bytes
0 to 3.
0 to 3.
To address the fifth digital input, for example, we enter the following address:
%I 0 . 4
%I
identifies here the address type as input,
0
the byte address and
4
the bit address.
The byte address and the bit address are always separated by a period.
Note:
For the bit address, a 4 is specified at the 5th input because counting starts with 0.
.
To address the 10th output, we specify the following address:
To address the 10th output, we specify the following address:
%O 1 . 1
%O
identifies here the address type as output,
1
the byte address and
1
the bit address.
The byte address and the bit address are always separated by a period.
Note:
For the bit address, a 1 is specified at the 10th output, because counting starts with 0.
32 digital
inputs
Byte 0
Bit to 7
Byte 1
Bit 0 to 7
Byte 2
Bit 0 to 7
Byte 3
Bit 0 to 7
inputs
Byte 0
Bit to 7
Byte 1
Bit 0 to 7
Byte 2
Bit 0 to 7
Byte 3
Bit 0 to 7
32 digital
outputs
Byte 0
Bit 0 to 7
Byte 1
Bit 0 to 7
Byte 2
Bit 0 to 7
Byte 3
Bit 0 to 7
outputs
Byte 0
Bit 0 to 7
Byte 1
Bit 0 to 7
Byte 2
Bit 0 to 7
Byte 3
Bit 0 to 7