Addressing S7-300 Modules

Slot Numbers

The slot numbers in the rack of an S7-300 simplify addressing in the

S7-300  environment. The position of the module in the rack determine the first

address on a module.

Slot 1

Power supply. This is the first slot by default.

A power supply module is not absolutely essential. An S7-300  can also be

supplied with 24V directly.

Slot 2

Slot for the CPU.

Slot 3

Logically reserved for an interface module (IM) for multi-tier configurations using

expansion racks. Even if no IM is installed, it must be included for addressing

purposes.

You can physically reserve the slot (such as for installing an IM at a later date) if

you insert a DM370 dummy module.

Slots 4-11

Slot 4 is the first slot that can be used for I/O modules, communications

processors (CP) or function modules (FM).

Addressing examples:

• A DI module in slot 4 begins with the byte address 0 .

• The top LED of a DO module in slot 6 is called Q8.0 .

Note

Four byte addresses are reserved for each slot. When 16-channel DI/DO

modules are used, two byte addresses are lost in every slot!

Multi-Tier Configurations

The slots also have fixed addresses in a multi-tier configuration.

Examples:

• Q7.7 is the last bit of a 32-channel DO module plugged into slot 5 of rack 0.

• IB105 is the second byte of a DI module in slot 6 of rack 3.

• QW60 is the first two bytes of a DO module in slot 11 of rack 1.

• ID80 is all four bytes of a 32-channel DI module in slot 8 in rack 2.

Address  Overview

Views the I/O addresses of the station configured. Select: View -> Address Overview …

Abbreviations:

R Rack number

S Slot number of the relevant module

DPRelevant only when Distributed Peripherals (I/O) are used

IF Interface module ID when programming the M7 system (in C++).

Slot dependent Addressing 

The modules are assigned fixed slot-dependent addresses with the S7-300  (CPUs without DP interface) and S7-400 (without hardware configuration).

Variable Addressing

With the S7-300  (CPUs with integrated DP interface) and with the S7-400 you can assign parameters to the starting addresses of the modules.

What to Do

When you double-click a digital or an analog module, the parameter assignment

screen is opened. After you choose the "Addresses" tab, you can cancel

"System selection". You can now define the starting address in the "Start" box. If

the address is already used, an error message is triggered.

Part process images can be defined only in the S7-400 . That way, specific

inputs and outputs (such as time-critical signals) can be combined into one

group. A system function triggers the updating of a part process image in the

user program.

Note

After a CPU memory reset, the parameters, and therefore also the addresses

are lost. This means that the slot-dependent addresses of the S7-300  or the

default addresses of the S7-400  are valid once more.

Hardware Configuration and Parameter Assignment

HW Configuration

The modules are supplied from the factory with preset parameters. If these

default settings are OK, a hardware configuration is not necessary.

A configuration is necessary:

• if you want to modify preset parameters or addresses of a module (such as

to enable the hardware interrupt of a module)

• if you want to configure communication connections

• with stations that have distributed peripherals (PROFIBUS-DP)

• with S7-400  stations that have several CPUs (multicomputing) or

expansion racks

• with fault-tolerant programmable logic controllers (option package).

Setpoint Configuration 

When you configure a system, a setpoint configuration is created. It contains a hardware station with the planned modules and the associated parameters. The

PLC system is assembled according to the setpoint configuration. During

commissioning, the setpoint configuration is downloaded to the CPU.

Actual Configuration

In an assembled system, the actual existing configuration and parameter

assignment of the modules can be uploaded from the CPU. This creates a new

HW station in the project.

A configuration upload is necessary, for example, if the project structure does

not exist locally at the PG. After the actual configuration is read out, you can set

parameters and add part numbers.

Notes

With the S7-400, the CPU can be assigned parameters in such a way, that

when there are differences between the setpoint configuration and the actual

configuration, the CPU startup is interrupted.

To call the HW Config tool, there must be a hardware station in the SIMATIC

Manager.

Starting the HW Configuration Editor

HW Config

This tool helps you configure, assign parameters to and diagnose the hardware.

Starting HW Config

To start the HW Config tool:

• select a hardware station in the SIMATIC Manager and choose the Edit --> Open Object menu or

• double-click the hardware object.

"Hardware Configuration"

This is a window in the "HW Config“ application you use for inserting components from the "Hardware Catalog" window.

The title bar of this window contains the name of the project and the station

name.

"Hardware Catalog"

To open the catalog:

• select the View -> Catalog menu or

• click the icon in the toolbar.

If “Standard” is selected as the catalog profile, all racks, modules and interface

modules are available in the "Hardware Catalog" window.

You can create your own catalog profiles containing frequently used elements

by selecting the menu options Options -> Edit Catalog Profiles.

You can add Profibus Slaves that do not exist in the catalog later on. To add

slaves, you use GSE files that are provided by the manufacturer of the slave

device. The GSE file contains a description of the device. To include the slave in

the hardware catalog, use the Options -> Install New GSE Files menu and then

Options -> Update Catalog. You will find the new devices in the catalog under

Profibus, additional field devices.

Generating a Hardware Setpoint Configuration

Generating a Setpoint  Configuration

This means specifying how the modules are to be arranged in the rack. This configuration, specified by you, is referred to as the setpoint configuration.

Rack

For example, you open a SIMATIC  300 station in the Hardware Catalog.

Opening the "RACK-300" folder shows the icon for a DIN rail. You can insert this

in the "Hardware Configuration" window by double-clicking on it (or using drag &

drop).

Two rack component lists then appear in the two-part window: a plain list in the

top part and a detailed view with order numbers, MPI addresses and I/O

addresses in the bottom part.

Power Supply

If a load current power supply is required double click or use drag & drop to

insert the appropriate "PS-300" module from the catalog in slot no.1 in the list.

CPU

You select the CPU from the "CPU-300" folder, for example, and insert it in slot

no. 2.

Slot No. 3

Slot no. 3 is reserved as the logical address for an interface module (for multitier

configurations).

If this position is to be reserved in the actual configuration for the later

installation of an IM, you must insert a dummy module DM370 (DUMMY).

"Inserting" Modules

From slot no. 4 onwards, you can insert a choice of up to 8 signal modules

(SM), communications processors (CP) or function modules (FM) from the

HardwareCatalog using drag & drop or with a double-click.

The slots on which the selected module can be inserted are automatically

highlighted in green.

Copying a Block from the Standard Library

Task

For later use, copy the FC105 block from the STEP7 "Standard Library" into the

Blocks folder of the Step7 Program "My_Program" in the project "My_Project".

What To Do

1. Open the "Standard Library" in the SIMATIC Manager:

File > Open... -> select the "Libraries" tab -> choose "Standard Library" in the

list -> confirm

2. In the project "Standard Library" open the Blocks folder of the S7 Program

"TI-S7-Converting Blocks"

3. Display your project called "My_Project" and the "Standard Library" at the

same time in two windows in the SIMATIC  Manager

Window > Arrange > Horizontally

4. Using drag & drop, copy the FC 105 block from the "Standard Library" into

your program folder "My_Program"

5. Close the library.

Result

The FC 105 block is stored in the Blocks folder of your Step7 Program called

"My_Program" in addition to the still empty OB 1.

Notes

Libraries are used for storing blocks which contain standardized functions. You

can copy the blocks from the library into any project you wish. If the name

(number) of the block you are copying already exists, you can rename the library

block (number) when you insert the block into your program folder.

Performing a CPU Memory Reset and Warm Restart

Task

You are to perform a CPU memory reset and check whether the memory reset

was successful.

What To Do

• Carry out the memory reset according to the steps in the slide above

• Check the success of the memory reset. The memory reset was successful

when only system blocks (SDBs, SFCs, SFBs) are left in the CPU

in the SIMATIC Manager, select the Step7 Program folder "My_Program" ->

switch to the Online view.

Notes

When the CPU memory is reset, all user data in the CPU are deleted.

To make sure that no “old” blocks are left in the CPU, a memory reset of the

CPU should be performed. The following takes place during a memory reset:

• All user data are deleted

(with the exception of the MPI parameter assignments).

• Hardware test and initialization

• If an Eprom memory card is installed, the CPU copies the EPROM contents

back into the internal RAM after the memory reset.

• If no memory card is installed, the preset MPI address is retained. If,

however, a memory card is installed, the MPI address stored on it is loaded.

• The contents of the diagnostic buffer (which can be displayed with the PG)

are retained.

Offline / Online View in the SIMATIC Manager

Offline View

In the project window of the SIMATIC  Manager, the offline view displays the

project structure stored on the hard disk of the programming device.

The " Step7 Program" folder contains the "Sources" and "Blocks" objects.

The "Blocks" folder contains the system data created with the HWConfig tool

and the blocks created with the LAD/STL/FBD Editor.

Online View

The online view shows the offline project structure in the left window and in the

right window it shows the blocks stored online in the selected CPU.

As a result, the " Step7 Program" seen in the online view only contains the "Blocks"

folder which contains the following objects:

• System data blocks (SDB)

• User blocks (OB, FC, FB)

• System blocks (SFC, SFB).

Changing Views

Changing between offline and online view takes place:

• through the View -> Offline or View -> Online menu items

or

• with the corresponding symbol in the toolbar:

Online

Offline

Note

You can arrange the "ONLINE" and "OFFLINE" views next to each other or

under each other when you use the Window -> Arrange option in the menu bar.

Standard Library

Introduction

Libraries are used to store reusable blocks.The blocks can be copied into a

library from existing projects or they can be created directly in the library

independent of projects.

Standard Library

A Standard Library is installed when you install STEP 7. You can access this standard library from the SIMATIC  Manager (File -> Open -> Libraries) or from

the Block Editor (Overviews -> Libraries). The library contains the following S7

programs:

Communication Blocks:

FCs (functions) for communication between the CPU and the distributed I/O

via communication processors.

Organization Blocks: Organization blocks (OBs).

S5-S7 Converting Blocks:

Blocks that emulate STEP 5 standard function blocks and that are necessary for converting STEP 5 programs.

TI - Step7 Converting Blocks: Generally usable standard functions such as analog value scaling.

IEC Function Blocks:

Blocks for IEC functions (IEC: International Electrotechnical Commission), such

as for processing time and date information, for string processing and for

selecting maximum and minimum.

PID Control Blocks: Function blocks (FBs) for PID closed-loop controls.

System Function Blocks: System functions (SFCs) and System function blocks (SFBs).

Miscellaneous Blocks: 

FCs and Fs for switching between daylight savings time and and standard time

(summer and winter times).

Note Additional libraries are added when optional software is installed.