Siemens SIMATIC S7-1200 User manual

S7-1200 Getting started with S7-1200
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Preface
Quick review
1
Installation
2
Create a simple latch circuit
3
Complete the user program
4
Use a watch table for
monitoring
5
SIMATIC
S7-1200
Getting started with S7-1200
Getting Started
11/2009
A5E02486791-01

Legal information
Legal information
Warning notice system
This manual contains notices you have to observe in order to ensure your personal safety, as well as to prevent
damage to property. The notices referring to your personal safety are highlighted in the manual by a safety alert
symbol, notices referring only to property damage have no safety alert symbol. These notices shown below are
graded according to the degree of danger.
DANGER
indicates that death or severe personal injury will result if proper precautions are not taken.
WARNING
indicates that death or severe personal injury may result if proper precautions are not taken.
CAUTION
with a safety alert symbol, indicates that minor personal injury can result if proper precautions are not taken.
CAUTION
without a safety alert symbol, indicates that property damage can result if proper precautions are not taken.
NOTICE
indicates that an unintended result or situation can occur if the corresponding information is not taken into
account.
If more than one degree of danger is present, the warning notice representing the highest degree of danger will
be used. A notice warning of injury to persons with a safety alert symbol may also include a warning relating to
property damage.
Qualified Personnel
The product/system described in this documentation may be operated only by personnel qualified for the specific
task in accordance with the relevant documentation for the specific task, in particular its warning notices and
safety instructions. Qualified personnel are those who, based on their training and experience, are capable of
identifying risks and avoiding potential hazards when working with these products/systems.
Proper use of Siemens products
Note the following:
WARNING
Siemens products may only be used for the applications described in the catalog and in the relevant technical
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Disclaimer of Liability
We have reviewed the contents of this publication to ensure consistency with the hardware and software
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Industry Sector
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A5E02486791-01
Ⓟ 10/2009
Copyright © Siemens AG 2009.
Technical data subject to change

Getting started with S7-1200
Getting Started, 11/2009, A5E02486791-01 3
Preface
As part of the SIMATIC commitment to "totally
integrated automation" (TIA), the S7-1200 product
family and the STEP 7 Basic programming package
give you the tools for creating your automation
application. The compact design, low cost, and powerful
features make the S7-1200 compact controller a perfect
solution for controlling small applications.
The examples in this document guide your first steps in
the world of S7-1200, teaching you the basic skills
within the shortest possible time.
Note
Review the
S7-1200 Programmable Controller System Manual for safety guidelines
This quick-start guide provides only a quick introduction to the world of S7-1200. Before
performing the exercises in this quick-start guide, review the safety guidelines and other
information in the
SIMATIC S7-1200 Programmable Controller System Manual .
Parts list
Description Quantity Order number
CPU 1212C AC/DC/RLY 1 6ES7212-1BD30-0XB0
Simulator: SIM 1274 (digital inputs) 1 6ES7274-1XF30-0XA0
Standard Ethernet CAT5 cable 1 6XV1850-2GH20
STEP 7 Basic programming software 1 6ES7822 -0AA00-0YA0
The starter kit also contains the S7-1200 documentation collection CD.
Note
You must provide a power cord for the CPU.
The CPU 1212C AC/DC/RLY requires 120/240 VAC. You must provide a power cord and
connect it to the CPU. For any other CPU, refer to the
S7-1200 Programmable Controller
System Manual
for power requirements and installation procedures.

Preface
Getting started with S7-1200
4 Getting Started, 11/2009, A5E02486791-01
Contact information
For additional information, refer to the S7-1200 programmable controller system manual .
Use the customer support web site (http://www.siemens.com/automation/support-request)
to search for specific information about products or to contact technical support
representatives.
Contact your Siemens distributor or sales office for assistance in
answering any technical questions, for training, or for ordering S7
products. Because your sales representatives are technically trained
and have the most specific knowledge about your operations,
process and industry, as well as about the individual Siemens
products that you are using, they can provide the fastest and most
efficient answers to any problems you might encounter.

Getting started with S7-1200
Getting Started, 11/2009, A5E02486791-01 5
Table of contents
Preface ...................................................................................................................................................... 3
1 Quick review .............................................................................................................................................. 7
1.1 Basic information about how the CPU works.................................................................................8
1.1.1 Tasks performed every scan cycle ................................................................................................8
1.1.2 Operating modes of the CPU.........................................................................................................9
1.1.3 Digital data stored in bits, bytes, words and more.......................................................................10
1.1.4 Data types supported by the S7-1200 .........................................................................................11
1.1.5 Memory areas of the S7-1200 .....................................................................................................12
1.2 From schematic diagram to user program...................................................................................13
1.2.1 Converting the schematic to LAD instructions.............................................................................14
1.2.2 Basic electrical circuits.................................................................................................................16
1.3 Basic features of STEP 7 Basic...................................................................................................18
1.3.1 Help when you need it .................................................................................................................19
1.3.2 Printing from the online help ........................................................................................................20
1.3.3 Inserting instructions ....................................................................................................................21
1.3.4 Dragging and dropping between editors......................................................................................22
1.3.5 Detecting the configuration of a CPU ..........................................................................................23
1.3.6 Changing the settings for the work area ......................................................................................24
2 Installation ............................................................................................................................................... 25
2.1 Read this first for safety information ............................................................................................25
2.2 Dimensions and guidelines..........................................................................................................26
2.3 Connecting the hardware.............................................................................................................27
2.4 Installing STEP 7 Basic................................................................................................................28
3 Create a simple latch circuit..................................................................................................................... 29
3.1 Create a project for your user program........................................................................................30
3.2 Create a simple network in your user program............................................................................31
3.3 Enter the tags and addresses for the instructions .......................................................................33
3.4 Configure the CPU.......................................................................................................................35
3.5 Download the user program to the CPU......................................................................................37
3.6 Test the operation of your sample user program.........................................................................38
3.7 Reviewing the tasks for the first exercise ....................................................................................39
4 Complete the user program ..................................................................................................................... 41
4.1 Add an on-delay timer to delay the start of an output..................................................................42
4.2 Turn on an output for 5 seconds..................................................................................................45
4.3 Editing your user program for a different structure ......................................................................48

Table of contents
Getting started with S7-1200
6 Getting Started, 11/2009, A5E02486791-01
5 Use a watch table for monitoring ............................................................................................................. 51
5.1 Create a watch table ................................................................................................................... 52
5.2 Monitor the data values in your CPU .......................................................................................... 53
5.3 Monitor the status in the LAD editor............................................................................................ 54
5.4 Force an input to a specific value ............................................................................................... 54
5.5 Going online ................................................................................................................................ 56
5.6 Building on a good beginning...................................................................................................... 56
Index........................................................................................................................................................ 57

Getting started with S7-1200
Getting Started, 11/2009, A5E02486791-01 7
Quick review 1
With an integrated power supply and a variety of on-board input and output circuits, the
S7-1200 CPU is a powerful controller. After you download your program, the CPU monitors
the inputs and changes the outputs according to the logic of your user program, which can
include Boolean logic, counters, timers, and complex math operations.
① Power connector
② Removable user wiring connectors
(behind the doors)
③ Status LEDs for the on-board I/O
④ PROFINET connector (on the bottom
of the CPU)
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To communicate with a programming
device, the CPU provides a built-in
PROFINET port. With the PROFINET
network, the CPU can communicate with
HMI panels or another CPU.
Feature CPU 1212C
Physical size 90 mm x 100 mm x 75 mm
Work memory
Load memory
Retentive memory
25 Kbytes
1 Mbyte
2 Kbytes
On-board digital I/O
On-board analog I/O
8 inputs and 6 outputs
2 inputs
Process image (Input)
Process image (Output)
Bit memory (M)
1024 bytes
1024 bytes
4096 bytes

Quick review
1.1 Basic information about how the CPU works
Getting started with S7-1200
8 Getting Started, 11/2009, A5E02486791-01
1.1 Basic information about how the CPU works
1.1.1 Tasks performed every scan cycle
The scan cycle provides consistent logic through the execution of the user program for a
given cycle and prevents the flickering of physical output points that might change state
multiple times in the process image output area. Each scan cycle includes writing the
outputs, reading the inputs, executing the user program instructions, and performing system
maintenance or background processing.
Under default conditions, all digital and analog I/O points use an internal memory area called
the "process image" to update the I/O synchronously with the scan cycle. The process image
contains a snapshot of the physical inputs ("I memory") and outputs ("Q memory") on the
CPU, signal board, and signal modules.
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A The input area of the process image (I memory) is cleared.
B The outputs are initialized with the last value.
C Any start-up logic (contained in special code blocks) is executed.
D The state of the physical inputs is copied to I memory.
E Any interrupt events are queued for processing during RUN mode.
STARTUP
mode
F The writing of the output area of the process image (Q memory) to the
physical outputs is enabled.
① Q memory is written to the physical outputs.
② The state of the physical inputs is copied to I memory.
③ The logic of your user program is executed.
④ The self-test diagnostics are performed.
RUN mode
⑤ Interrupts and communications are processed during any part of the
scan cycle.

Quick review
1.1 Basic information about how the CPU works
Getting started with S7-1200
Getting Started, 11/2009, A5E02486791-01 9
1.1.2 Operating modes of the CPU
The CPU has three modes of operation: STOP mode, STARTUP mode, and RUN mode.
Status LEDs on the front of the CPU indicate the current mode of operation.
● In STOP mode, the CPU is not executing the program, and you can download a project.
● In STARTUP mode, the CPU executes any startup logic (if present). Interrupt events are
not processed during the startup mode.
● In RUN mode, the scan cycle is executed repeatedly. Interrupt events can occur and be
processed at any point within the program cycle phase.
Note
You cannot download a project while the CPU is in RUN mode. You can download your
project only when the CPU is in STOP mode.
The CPU does not have a physical switch for changing the operating modes (STOP or
RUN). When you configure the CPU in the device configuration, you configure the start-up
behavior in the properties of the CPU. The STEP 7 Basic provides an operator panel for
changing the operating mode of the online CPU (Page 56).
Use the button on the operator panel to change the operating
mode (STOP or RUN). The operator panel also provides an
MRES button for resetting the memory.
The color of the RUN/STOP indicator shows the current
operating mode of the CPU:
Yellow indicates STOP mode.
Green indicates RUN mode.
Flashing indicates STARTUP mode.

Quick review
1.1 Basic information about how the CPU works
Getting started with S7-1200
10 Getting Started, 11/2009, A5E02486791-01
1.1.3 Digital data stored in bits, bytes, words and more
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The smallest unit of information in a digital system is known as
a "bit" (for "binary digit"). A bit stores one of two possible
states, either a "0" (false or not true) or "1" (true).
A light switch is an example of a "binary" system with only two
states. The light switch determines either a "light on" or a "light off"
state, and this "value" can be stored in one bit. The digital value of
the light switch answers the question: "Is the light on?" If the light is
switched on ("true"), then the value is 1. If the light is switched off
("false"), then the value is 0.
The CPU organizes bits of data into groups. A group of 8 bits ① is called a byte ②.
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Each bit in the group is defined exactly by a separate
position with its own address. Each bit has a byte address
and bit addresses 0 to 7.
A group of 2 bytes is called a "word". A group of 4 bytes is called a "double word".
③ Word
② Byte
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① Bit
You use the binary number system (base 2) for counting the numbers. A word can
represent an integer number from -32768 to +32767. The bit with the value 215 is used to
denote a negative number (when position 215 has the value "1" the number is negative).
Note
The CPU also supports a grouping of 8 bytes that form a "long real" data type (LReal) for
storing very large or very precise values. The range for the LReal is: +/-2.23 x 10-308 to +/-
1.79 x 10308