Lecture Number 4 Siemens S7

In this session… In this session, you will learn about the Siemens S7 system

Learning outcomes At the end of this session you should be able to: Describe the basic S7 system Understand the addressing system of the PLC List the basic devices available in the PLC

Introduction to S7 By C Mayhew

Introduction to The Siemens S7 System

Controllers There are three main controller models: Siemens S7 200 Siemens S7 300 Siemens S7 400 The size and power of the controllers increases with different models. For example, the S7 200 is a small application model and the S7 400 is a large rack system with powerful communications functions and instructions.

S7 300 Series In this lesson we will investigate the S7 313C-2 DP CPU, a S7 300 series processor. This processor has integrated digital I/O as well as the capability for expansion via a rack. The inputs are Sinking Inputs and the outputs are PNP BJT. The processor has two communications interfaces: Profibus DP Serial Interface (MPI) The user programme is stored on a removable EEPROM on the CPU, up to 64k of EEPROM memory is available. The cost of this particular processor is in the region of £1000.

S7 300 Series Some of the processors in this series have integrated analogue also. The analogue I/O can be configured for a range of signal types, including: ±10V 4~20mA

S7 313C-2 DP CPU EEPROM Slot Indicator Lights Digital I/O Start/Stop Switch Digital I/O Communications Interfaces

S7 Programming Programming of the S7 300 Series PLC is achieved using the S7 Software package. The software is IEC 61131 compliant and has many add on and integrated functions including: Protool HMI Configuration Software Add On Integrated Bus Management Tool

S7 Programming Software Bus Configuration Manager Device Library PLC Station on Profibus DP/ASi Gateway on Profibus Hardware Configuration Manager CPU with Integrated I/O Integrated I/O parameters Programming Environment Ladder Symbols. Programme Screen Download Button Monitor Button Instruction Library

S7 Programming Formats The S7 Software can be used to programme in the following formats: Ladder (LAD) Function Block (FBD) Mnemonic List (STL) Scripts can also be generated by the software.

Ladder Format Ladder Symbols used to build Ladder

Function Block Format Logic Symbols used to build programme function.

Mnemonic List Format (STL) Mnemonic listing

S7 Addressing Schemes I/O The I/O addressing of the S7 range of PLC systems is much the same as the S5 PLC system. I/O uses Byte and Bit addressing. I (E) is used for Input Identification. Q (A) is used for output identification. An input connected at Byte 3, Bit 5 would therefore be addressed as: I3.5 Bit Byte De-limiter Identifier

S7 Addressing Schemes Memory The internal memory bits of the S7 PLC is prefixed with the letter, M (Memory) Memory also uses Byte and Bit addressing. A memory bit at Byte 4, Bit 2 would therefore be addressed as: M4.2 Bit Byte De-limiter Identifier

Timers and Counters The internal timers and counters are used in much the same way as the S5 software and machines. The main difference in their use is the data formats used with the functions. Delay On Timer set for 3.5 Seconds Count Up/Down Counter set for count of 10

Timers Types, SD

Timers Types, SF

Timers Types, SS

Timers Types, SP

Timers Types, SE

Block Structure The Siemens PLC gives us the functionality of writing programmes in ‘Blocks’. This means that large programmes can be broken down into subroutines and ‘linked’ using Jump commands as and when required. This is considered to be good programming and can speed up programme execution times. OB1 UC FC1 UC FC2 UC FC3 :BE FC1 FC2 FC3 The main block types we will be interested in are: OB - Organisation Blocks FC - Functions DB - Data Blocks

Summary You should now have a basic understanding of the Siemens S7 system