Siemens s7 300-400-s7 graph for s7-300 400 programming sequential control systems

First Steps
The Getting Started for this product is not a stand-alone description.
It is a part of the manual and can be called via "First Steps".
SIMATIC
S7 Graph for S7-300/400
Programming Sequential Control Systems
Getting Started Edition 04/2001
First Steps
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Copyright © Siemens AG 2001 All rights reserved
The reproduction, transmission or use of this document or its
contents is not permitted without express written authority.
Offenders will be liable for damages. All rights, including rights
created by patent grant or registration of a utility model or design,
are reserved.
Siemens AG
Bereich Automatisierungs- und Antriebstechnik
Geschaeftsgebiet Industrie-Automatisierungssysteme
Postfach 4848, D- 90327 Nuernberg
Disclaimer of Liability
We have checked the contents of this manual for agreement with
the hardware and software described. Since deviations cannot be
precluded entirely, we cannot guarantee full agreement. However,
the data in this manual are reviewed regularly and any necessary
corrections included in subsequent editions. Suggestions for
improvement are welcomed.
©Siemens AG 2001
Technical data subject to change.
Siemens Aktiengesellschaft 6ES7 811-0CC04-8XB0
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S7 Graph for S7-300/400 Programming Sequential Control Systems
A5E00105265-01 3-1
3 Designing a Sequential Control System
Based on the Example of a Drill
Welcome to the S7 Graph Beginner’s Example
If you take an hour to work through the beginner’s example, you will learn how to
create a sequential control system for automating the drill as described below.
You first learn how to configure a sequential control system efficiently and will then
be guided step by step through the tasks you need to perform in the SIMATIC
Manager and in S7 Graph so that you can
• create the sequential control system,
• download it to the CPU and
• test it.
The correctly programmed sample is supplied with S7 Graph as a project called
"ZEn02_01_S7Graph_Drill".
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Designing a Sequential Control System Based on the Example of a Drill
3-2 A5E00105265-01
Requirements
To allow you to program and test the "drill" example, you require the following
hardware and software:
• Programming device/PC with
- STEP 7 standard package and the S7 Graph optional package
- MPI connection to the programmable logic controller
• A programmable logic controller (in our example an S7-300) consisting of the
following: standard rail, 24V power supply, CPU 314, and a digital input/output
module (8DI + 8DO)
• As an alternative to the PLC: The "PLC Simulation" S7 optional package
Procedure for Creating a Sequential Control System
The flow diagram illustrates the procedure for creating the sequential control
system for the drill example:
Create symbol table
Specify structure of sequencer
and define signals for system
Create drill project in the
SIMATIC Manager
Create sequencer:
• create and open S7 Graph FB1 in
the SIMATIC Manager
• Program sequencer
Program OB1 with FB1 call and
corresponding instance DB (DB1)
Download sample program (DB1, FB1,
OB1) to the CPU in the SIMATIC
Manager and test the sequencer
Symbolic
programming
yes
no
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3.1 Technological Task and Functional Diagram
Task
You want to program a sequential control system to automate a drill. The setup of
the drill is shown by a technological drawing and the process sequence in the form
of a function diagram.
Technological Drawing - Set Up of the Drill
The drill consists of the following elements:
• Drill motor with feedback signals for drill running/stopped
• Start button and coolant switch
• Cooling pump with feedback signal for coolant pressure reached
• Clamping device with feedback signal for selected clamp pressure reached
• Carriage raise/lower drill with limit switches for drill up/down
Raise drill
Drill motor on
Feedback signal:
- Drill running
- Drill stopped
Cooling pump on
Feedback signal
Coolant pressure reached
Start button
Feedback signal:
Selected clamping pressure
reached
Limit switch:
Drill up
Limit switch:
Drill down
Coolant switch
Drill motor
Carriage
Clamp deviceCooling pump
Lower drill
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3-4 A5E00105265-01
Initial State
The initial state of the drill is defined as follows:
• The drill motor and cooling pump are stopped
• The carriage/drill is in the upper position
• There is no work piece in the clamping device
Functional Diagram - Drilling Sequence
The entire drilling sequence can be divided into the following sections:
• Insert work piece (manual)
• If required, set switch for coolant (depending on the material)
• Start the machine with the start button (drill motor starts up)
• Clamp the work piece with the selected clamp pressure
• Start the cooling pump (if coolant selected)
• Lower drill and carriage to the bottom target position (drill)
• Wait 0.5 seconds at lower target position (drill)
• Raise drill with carriage to upper target position
• Remove work piece, turn off drill motor and cooling pump
• Remove work piece (manual)
Motor
running
stopped
Carriage
up
down
Element State
Clamping
device-
On
Off
Start
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A5E00105265-01 3-5
3.2 Selecting the Structure of the Sequencer
Before you create the program for the sequencer, you should include a concept
phase in which you break down the drilling operation into single steps. The basis of
the concept design is the technological drawing and the flowchart.
Dividing the Drilling Process into Individual Steps - Structure of the Sequencer
The drilling process is described by S7 Graph in the form of a sequencer. A
sequencer represents a sequence of single steps and conditions that control how
the process moves on to the next single step. To specify the structure of the
sequencer, follow the steps outlined below:
1. Break down the drilling process into steps and specify the order of the steps
(for example "step S2 follows S1" or "step S3 follows either step S4 or S7").
2. For each step, specify the actions that must be performed in the step (for
example in S1 the action "Drill ready" or in S3 the action "Turn on drill motor").
3. Then decide for every step which conditions must be met so that the process
can move on to the next step (for example for T1 the condition "Drill started -
start button pressed" or for T5 the condition "Drill in upper position").
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3-6 A5E00105265-01
T2
S2
T8
T3
T7
S3
S1
T4
T1
T6
S7
S4
Drill ready (initial step)
Clamp work piece
Turn on drill motor
Turn on cooling pump
Lower drill (start drilling)
Drill program started (start button
pressed)
Work piece clamped with selected
pressure
Drill motor running at selected speed
(without coolant)
Coolant pressure reached
Drill in lower position
Drill motor running at selected speed
(with coolant)
S5
S6
T5
T6
S1
Raise drill
Release work piece, turn off drill motor
and cooling pump
Drill in upper position
Work piece is released, cooling
pump stopped, drill motor stopped
Waiting time 500 ms
S = step
T = transition
Monitor clamping
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A5E00105265-01 3-7
3.3 Defining the System Signals
Once you have broken down the drilling operation into individual steps, you should
then define the input and output parameters for each step. The basis of the
concept design is the technological drawing and the flowchart.
Defining Inputs and Outputs
List the inputs and outputs for the drill in the form of a table.
If you want to program symbolically, enter the required symbolic names (for
example input I 0.4 "Cl_press_ok") for the absolute inputs and outputs and any
comments that will make the program easier to understand (for example
"Workpiece clamping pressure reached").
In the drill example, it is assumed that the switches and contactors of the drill are
controlled via the inputs and outputs of the digital input/output module of the
S7-300 programmable controller. The input/output module has 8 inputs and 8
outputs. The default values of the input and output addresses of the module
inserted in slot 4 are as follows: I 0 to I 0.7 and Q =0.0 to Q 0.7.
Absolute
Addresses
Symbolic
addresses
Explanation
Inputs in the program (I)
I 0.0 Dr_mot_running Feedback signal for drill running at selected speed
I 0.1 Dr_mot_stopped Feedback signal for drill stopped
I 0.2 Drill_down Limit switch for drill in lower position
I 0.3 Drill_up Limit switch for drill in upper position
I 0.4 Cl_press_ok Feedback signal for work piece clamping pressure
reached
I 0.5 Coolant_sel Selector for coolant (dependent on work piece)
I 0.6 Cool_press_ok Feedback signal for coolant pressure reached
I 0.7 Start_button Start button of the drill
Outputs in the program (Q)
Q 0.0 Dr_mot_on Turn on drill motor
Q 0.1 Cool_pump_on Turn on cooling pump (dependent on work piece)
Q 0.2 Lower_drill Lower drill and carriage to bottom limit position
Q 0.3 Raise_drill Raise drill and carriage to the upper limit position
Q 0.4 Clamp_workp Clamp work piece at required pressure
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3-8 A5E00105265-01
3.4 Creating the Drill Project in the SIMATIC Manager
Creating a Project
Projects for sequential control systems do not differ from other projects in STEP 7.
To create a new project in the SIMATIC Manager, follow the steps outlined below:
1. Select the menu command File > New.
2. Name the project "Drill".
Inserting an S7 Program
In this example, hardware configuration is unnecessary since the default
addressing of the input/output module in slot 4 is used. You can therefore
immediately insert an S7 program in the project folder in the SIMATIC Manager.
The S7 program serves as a folder for the blocks of the user program, the source
files and the symbols. Follow the steps below:
1. Select the "Drill" project.
2. Select the menu command Insert > Program > S7 Program.
3. Name the S7 program "Drill Program".
The folders for source files, blocks, and symbols are created automatically when
you insert an S7 program. An empty OB1 is also created in the Blocks folder.
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A5E00105265-01 3-9
3.5 Creating a Symbol Table
When you program in STEP 7, you work with addresses such as I/O signals,
memory bits, counters, timers, data blocks, and function blocks. You can access
these addresses in your program in absolute format (for example I1.1, M2.0,
FB21).
You will find the program much clearer and easier to read if you use symbols (for
example Motor_A_on) instead of the absolute addresses. To allow the use of
symbols, you can enter a name, the absolute address, the data type and a
comment for every address used.
Once you have defined a symbol, it can be used throughout the entire user
program of a programmable module.
Creating a Symbol Table
If you want to write your program using symbolic addresses, it is advisable to
create the symbol table at this point.
1. Open the symbol table in the "Drill Program" folder by double-clicking
"Symbols".
2. Edit the table as shown below.
3. Save the symbol table using the menu command Table > Save.
The entries 1 to 14 are required for symbolic representation of the inputs and
outputs. The entries 15 to 18 allow symbolic representation of the blocks.
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3-10 A5E00105265-01
3.6 Creating an S7 Graph FB and Programming a Sequencer
Creating an S7 Graph FB
The S7 Graph FB will contain the sequencer. To create an S7 Graph FB, follow the
steps outlined below:
1. Open the "Blocks" folder in "Drill Program" in the SIMATIC Manager.
2. Select the menu command Insert > S7 Block > Function Block.
3. Set "S7 Graph" as the language in the "Properties" dialog box.
Result: The empty FB with the default number 1 is created in the "Blocks"
folder.
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A5E00105265-01 3-11
Programming a Sequencer
After you have started the S7 Graph editor by double-clicking FB1 the system
inserts the first step (initial step) and the first transition. It is advisable to create the
structure at the "Sequencer" display level. To display conditions and actions,
activate the View > Display With > Conditions and Actions menu command.
Using the mouse and the "Sequencer" toolbar at the left-hand edge of the screen,
you can then position all the remaining steps and transitions, the alternative
branch and the jump from the end of the sequencer to the start of the sequencer.
There are two ways of doing this and both are illustrated here.
Method 1: "Direct" Mode
1. Select transition 1 and click with the mouse until the icon
insert step + transition
until you arrive at step/transition 6.
2. Select step 3 and then select the icon
open alternative branch.
This opens the alternative branch for supplying coolant. The branch begins
with transition 7.
3. With the mouse, select the icon
insert step + transition,
and insert step 7 (S7) and transition 8 (T8).
4. Select the icon
close alternative branch
and then select transition 3.
5. Now complete the sequencer structure by first selecting transition 6 and then
clicking on the icon
insert jump
and then selecting step 1.
Method 2: "Drag-and-Drop"
1. Return to the SIMATIC Manager and create function block FB2 in the "Blocks"
folder as described above. Once again select "GRAPH" as the source
language.
2. Start the S7 Graph editor by double-clicking FB2 in the "Blocks" folder.
3. Select the menu command Insert > Drag-and-Drop.
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3-12 A5E00105265-01
insert step + transition
and then click on the last transition of the individual elements until you arrive at
step/transition 6.
5. Select the icon
open alternative branch
and open the alternative branch for the coolant by clicking on step 3. The
branch begins with transition 7.
insert step + transition,
to insert step 7 (S7) and transition 8 (T8).
7. Select the icon
close alternative branch
and first select transition 8 and then transition 3.
8. Now complete the sequencer structure with
insert jump
by first selecting transition 6 and then step 1.
Note
Before you start to program step actions, close function block FB2. You only
created this FB to try out the second method of creating a sequencer structure.
When you close the FB, answer all prompts with "No". For the rest of the exercise,
you will be working in FB1.
3.7 Programming Step Actions
There are also two methods available for programming step actions and
transitions: Direct and Drag-and-Drop. The procedure described below assumes
you have selected the menu command Insert > Drag-and-Drop:
1. Select the menu command Insert > .
Result: The mouse pointer then appears as shown below:
2. Insert an empty action line by clicking the action box.
3. Enter the actions.
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A5E00105265-01 3-13
An action consists of an instruction and an address. For the drill program, four
different instructions are necessary in the steps:
• S Set output
• R Reset output
• N Non holding: As long as the step is active, the signal state of the
address is 1.
• D Delay: The address is set to 1 after the defined time has elapsed
following activation of the step and is reset when the step is deactivated.
3.8 Programming Transitions
The bit logic instructions "normally open contact", "normally closed contact" and
"comparator" are used for the step enabling conditions in the transitions. To
program transitions:
1. Set the "LAD" view and select the appropriate icons in the "LAD/FBD" toolbar
insert normally-open contact
insert normally-closed contact
insert comparator
2. Position the symbols at the appropriate points by clicking the transition lines.
You can exit the insert mode at any time with the ESC key.
3. Enter the addresses. Click the placeholder "??.?" of the required text field.
Then enter an absolute or symbolic address (for example I 0.7, "Start_switch").
4. If you wish, you can also enter a comment for the sequencer. In the
"sequencer" view, the comment field is at the top left and can be opened by
clicking it with the mouse.
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3-14 A5E00105265-01
The following figure shows the completed sequencer.
GRAPH: Programming s7 Sequential Control Systems - Drill...
File Edit Insert PLC Debug View Options Window Help
Drill
T1
Trans1
T4
Trans4
"Drill_d
own"
S2
Cla...
T2
Trans2
S3
Mo...
T3
Trans3
T7
Trans7
T8
Trans8
Drill_ready
Clamp_on
S "Clamp_workp"
Motor_on
S "Dr_mot_on"
Coolant_on
S "Cool_pump_on"
Lower_drill
N "Lower_drill""
S4
Low...
S7
Coo...
T6
"Start_but
ton"
Clamp_pres
s_ok"
"Drill_moto
r_running"
"Coolant_
sel"
"Cool_pres
s_ok"
S1
Dr...
"Drill_moto
r_running
"
"Coolant_
sel"
S5
Rai...
T5
Trans5
"Drill_up"
"Cl_press
_ok"
T6
Trans6
"Cool_press
_ok"
S6
Cla...
S1
CMP
Term_M_pump_off.T
T#500MS
Raise_drill
D "Raise_drill""
T#500MS
Term_M_pump_off
R ""Clamp_workp"
R "Dr_mot_on"
R "Cool_pump_on"
"Drill_mot
or_stopped
"
>=
When programming comparators, you can use the system information for steps as
the addresses. The addresses have the following significance:
• Step_name.T: current or last activation time of the step
• Step_name.U: current or last activation time of the step without the time of a
disturbance
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A5E00105265-01 3-15
3.9 Programming Monitoring Functions
To program monitoring functions:
1. Double-click on step 2 to change from the "sequencer" view to the "single step"
view.
2. Select the icon
insert comparator in the "LAD/FBD" toolbar
3. Position the comparator at the appropriate point on the supervision line and
enter the required monitoring time.
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3.10 Specifying the Standard Function Block
Executability of the S7 Graph FB
S7 Graph has two options available for creating FBs.
• Full code:
The entire code required to execute each S7 Graph FB is included in the FB. If
you have several S7 Graph FBs, this means a considerable increase in
memory requirements.
• Standard FC required:
To reduce memory requirements, S7 Graph has the two following alternatives:
You use a standard FC containing the main code sections for all FBs. This FC
is copied to your project automatically when you select this option. The FBs
produced using this method are considerably smaller.
For this example, use the compilation option "Full code".
The most suitable FC depends on the performance of your CPU. Select one of the
following standard FCs:
FC Number Functionality
FC72 As default, you work with FC72. Remember, that your CPU must be capable of processing
blocks with more than 8 Kbytes.
FC70/FC71 These two FCs are less than 8 Kbytes in size and can therefore be loaded on a smaller
CPU. FC70 uses the diagnostic functionality of SFC17/18 and can only be used on CPUs
that have these functions available. If your CPU does not have these functions, you must
use FC71 and do without diagnostic capability.
If you want to check whether or not your CPU contains these SFCs, select the menu
command PLC > Obtainable Nodes in the SIMATIC Manager or click the corresponding
button in the toolbar. Open the "Blocks" folder in the S7 program.
FC73 This block requires less than 8 Kbytes of memory so that it can be executed on all CPUs.
Using this FC considerably reduces the memory requirements of the S7 Graph FBs. You
must also select the option "Interface Description: Memory minimized" in the block
settings.
The following restrictions, do, however, apply:
The blocks created do not have diagnostic capability
When you monitor the sequential control system, you will see the status display only for
the selected active element.
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A5E00105265-01 3-17
Setting the Executability
Select the menu command Options > Block Settings and specify that the
S7 Graph FB can be executed with a standard FC in the Compile/Save tab. Enter
the FC number that matches the performance of your CPU.
The block is automatically copied to the user project if you select FC70/71, FC72 or
FC73 as the block number and there is not yet an FC with this number in the target
project. If you want to use a different number for the standard block, you must copy
and renumber yourself.
3.11 Saving and Closing the Sequencer
When you save the sequencer, it is automatically compiled.
1. Select the menu command File > Save.
Result: The "Select Instance DB" dialog box is opened with the default instance
DB (DB1).
2. Accept the settings by clicking "OK".
Result: The instance data block is automatically created in the "Blocks" folder.
Note
The warning "S1 without content" in the compiler log simply means that no action
is programmed in step 1.
3. To close the sequencer, select the menu command File > Close.
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3.12 Including the Sequencer in the STEP 7 Program
Programming OB1
The sequential control program for the drill is called and started in organization
block OB1. You can create OB1 in LAD, FBD, STL or SCL (here it was created in
LAD). Program OB1 as shown in the following diagram. Follow the steps below:
1. Open the "Blocks" folder in the "Drill Program" S7 program in the SIMATIC
Manager.
2. Start the LAD/STL/FBD editor by double-clicking OB1.
3. With the menu command View, select the programming language LAD.
4. Select segment 1 and insert the sequencer call using the program element
catalog by double-clicking FB1 (Seq_drill).
5. Type in the name of the corresponding instance data block (IDB_Seq_drill)
above the LAD box.
6. Select the input parameter INIT_SQ, insert a normally open element using the
"LAD" toolbar and label it M0.0 ("INIT_SQ"). Using this parameter, you can set
the sequencer to the initial step (in the example step 1) in the online mode.
7. Select the menu command File > Save and close the organization block with
the menu command File > Close.
Note
All other block parameters can be ignored for the example.
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3.13 Downloading the Program to the CPU and Testing the
Sequencer
Downloading the User Program
To allow you to download the program to the CPU, you must download all the
blocks (DB1, FB1, OB1, FC70/71, FC72 and/or. FC73) to the CPU of the
programmable controller in the SIMATIC Manager. Follow the steps outlined below:
1. Open the "Drill Program" S7 program in the SIMATIC Manager and select the
"Blocks" folder.
2. Select the menu command PLC > Download.
Caution
It is best to download the S7 Graph block in the STOP mode since following
downloading of the instance DB, the sequencer is automatically set to the initial
state.
You should only download S7 Graph blocks in the RUN-P mode when the
sequencer is in the initial state or in the OFF state. If you download the blocks the
sequencer in a different state, for example when overwriting an old block,
problems may occur in the synchronization of the sequencer with the process.
Testing the User Program
To test the user program, you require an online connection to a CPU.
3. Open the project window in the SIMATIC Manager.
4. Open the sequencer by double-clicking FB1.
5. Select the menu command Debug > Monitor.
Result: The program status is displayed (the initial step is active). Active steps
are displayed in color.
Caution
A monitoring time is programmed in step 2. If the step activation time exceeds the
configured monitoring time (500 ms) in the supervision condition, the system
recognizes a supervision error and the disturbed step is displayed in red. If a fault
occurs, you must first satisfy the condition for progressing to the next transition.
Using the PG function Debug > Control Sequencer you can then enter an
acknowledgment (see also "Control Sequencer").
This does not apply to the inching mode, since the step enabling condition must
be satisfied and the acknowledgment received within one cycle.
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3.14 Test Function: Control Sequencer
Control Sequencer is a test function with which you can test the sequencer in
S7 Graph in all modes. All the settings and entries for the dialog box have the
same effect as the corresponding FB parameters.
The entries in the "Control Sequencer" dialog box can be different from the settings
you used to compile the sequencers. The dialog box settings have priority.
"Control Sequencer" Dialog box
The "Control Sequencer" dialog box is used both as an output field that displays
the current settings and as an input field in which you can change the current
status.
If you acknowledge an error, initialize the sequencer, or want to change the step in
the manual mode, call the dialog box with the menu command Debug > Control
Sequencer.
Acknowledge
If the "Acknowledge errors" option is clicked, you acknowledge a pending error
message with the "Acknowledge" button. In this way, you can acknowledge a
disturbance caused, for example, by the configured monitoring time in Step 2 being
exceeded.
Note, however, that before you acknowledge the error you must make sure that the
supervision or interlock conditions that led to the error are no longer satisfied.
After an error has occurred, you can enable the next step in the sequencer by
satisfying the step enable condition because the last step enable condition in the
cycle in which you acknowledge has priority over the supervision. You must
nevertheless acknowledge the error.
If the error was caused because the undisturbed activation time Step name.U has
exceeded the configured monitoring time, you can move on the sequencer by
clicking the "Acknowledge" button.
This is possible because the Step name.U variable is set to "0" when you
acknowledge.
Initialize
With the "Initialize" button, you can restart the sequencer completely with the
defined initial step.
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Setting the Mode
If you click one of the round option buttons, you switch the sequencer to the
selected mode.
You can, for example, run your sequencer in the manual mode instead of the
automatic mode. In the manual mode, you can activate or deactivate any step.
Follow the steps outlined below:
1. Enter the step number of the step you want to process in the "Step number"
box or simply click the required step.
2. Select the action to be executed with the step:
- Activate The selected step is activated even if the preceding transition is
not satisfied.
- Deactivate The selected step is deactivated.
Note that before you activate a step you must first deactivate the currently active
step since only one step can be active at any one time in a linear sequencer. In
other words, you can only activate the required step when you have deactivated
the currently active step.
If you have set a new mode, the original mode is indicated in bold face.
After you have controlled your sequencer in the manual mode, you can return to
the automatic mode and close the "Control Sequencer" dialog box.
3.15 Modifying the Sequencer
Often, a program does not run as required at the first attempt. This means that
changes and modifications are required. This is also the case in our sample
program. The configured monitoring time in Step 2 is too short and the program
hangs at this step. The following section explains how to make the required
changes. You must first change to the "offline" mode.
Modifying the Monitoring Time
The monitoring time configured in Step 2 is 500 ms. To give you more time for
setting the "Cl_press_ok" variable, change the monitoring time to 5 s as explained
below:
1. Double-click on step 2 to change from the "sequencer" view to the "single step"
view.
2. Close the status by selecting the menu command Debug > Monitor or clicking
the following button: .
3. Enter the value 5 s for the monitoring time.
4. Save the sequencer with the menu command File > Save, since the sequencer
must be recompiled.
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Downloading the Modified Sequencer
Once you have compiled the sequencer, you must download it to the CPU. You
can download the sequencer in the SIMATIC Manager or in the S7 Graph editor. In
the S7 Graph editor, follow the steps outlined below:
1. With the FB open, select the menu command PLC > Download or click on the
Download button . The "Download" dialog box is opened.
2. Accept the defaults by clicking "OK".
3. Confirm the prompt to overwrite the existing blocks.
Include Instance DB
If you have not cleared the system default "Include Instance DB", S7 Graph checks
whether the instance DB has changed since it was last downloaded and whether it
must be updated. The option "Download with Instance DB" is clicked in the
"Download" dialog box.
Otherwise, S7 Graph does not check the instance DB and leaves you to decide
whether or not to download the instance DB again. The option "Download with
Instance DB" is not clicked in the "Download" dialog box.
Restarting the Status
To be able to monitor or control the sequencer again, restart Status by selecting
the menu command Debug > Monitor or by selecting the Monitor button.
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Siemens s7 300-400-s7 graph for s7-300 400 programming sequential control systems

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