Data Blocks
SIMATIC S7
Siemens AG 2006. All rights reserved.
Date:
File:
2/8/2012
PRO1_10E.1
SITRAIN Training for
Automation and Industrial Solutions
Objectives
Upon completion of this chapter the participant will ...
SIMATIC S7
Siemens AG 2006. All rights reserved.
...
understand the purpose of global data blocks
...
be familiar with elementary and complex data types
...
be able to monitor a data block
...
be familiar with the possibilities for addressing data block variables
Date:
File:
2/8/2012
PRO1_10E.2
SITRAIN Training for
Automation and Industrial Solutions
Data Blocks (DBs)
Accessible to all blocks
OB1
Function
FC10
Function
FC20
Global (shared)
data
DB20
Instance DB for FB1
Function
Block
FB1
SIMATIC S7
Siemens AG 2006. All rights reserved.
Date:
File:
2/8/2012
PRO1_10E.3
Instance data
DB5
SITRAIN Training for
Automation and Industrial Solutions
Overview of Data Types in STEP 7
Elementary
data types
(up to 32 bits)
• Bit data types (BOOL, BYTE, WORD, DWORD, CHAR)
• Mathematical data types (INT, DINT, REAL)
• Time types (S5TIME, TIME, DATE, TIME_OF_DAY)
• Time type (DATE_AND_TIME)
Complex
data types
(longer than 32 bits)
• Array (ARRAY)
• Structure (STRUCT)
• Character chain (STRING)
User-defined data types
(longer than 32 bits)
SIMATIC S7
Siemens AG 2006. All rights reserved.
UDT data type (User Defined
Data Type)
Date:
File:
2/8/2012
PRO1_10E.4
SITRAIN Training for
Automation and Industrial Solutions
Elementary Data Types in STEP 7
Keyword
Length (in bits)
BOOL
1
BYTE
8
Constants
Variables
1 or 0
I 1.0
B#16#A9
MB70
WORD
16
W#16#12AF
MW72
DWORD
32
QD40
DW#16#ADAC1EF5
CHAR
8
'w'
DBB4
S5TIME
16
S5T#5s_200ms
MW30
INT
16
DINT
32
123
#Value
L#65539
MD80
REAL
SIMATIC S7
Siemens AG 2006. All rights reserved.
32
1.2 or 34.5E-12
Date:
File:
DBD60
2/8/2012
PRO1_10E.5
SITRAIN Training for
Automation and Industrial Solutions
Complex Data Types
Keyword
Length (in bits)
Example
DATE_AND_TIME
64
DT#01-08-24-12:14:55:234-1
STRING
(character string with
max. 254 characters)
8 * (number of
´This is a string´
characters +2)
´SIEMENS´
ARRAY
(Group of elements
of the same data type)
userdefined
Measured values: ARRAY[1..20]
INT
STRUCT
(Group of elements
of different data types)
userdefined
Motor: STRUCT
Speed : INT
Current : REAL
END_STRUCT
UDT
UDT as block
(User Defined Data Type =
user-
"Template" consisting of
defined
STRUCT
Speed
elementary or complex
data types
SIMATIC
S7
Siemens AG 2006. All rights reserved.
UDT as array
element
Date:
File:
: INT
Current : REAL
UDT1
END_STRUCT
2/8/2012
PRO1_10E.6
Drive: ARRAY[1..4]
SITRAIN Training for
Automation and Industrial Solutions
Creating a Data Block
SIMATIC S7
Siemens AG 2006. All rights reserved.
Date:
File:
2/8/2012
PRO1_10E.7
SITRAIN Training for
Automation and Industrial Solutions
Entering, Saving, Downloading and Monitoring a Data Block
Declaration View
Data View
SIMATIC S7
Siemens AG 2006. All rights reserved.
Date:
File:
2/8/2012
PRO1_10E.8
SITRAIN Training for
Automation and Industrial Solutions
Initial Value, Actual Value, Initialization, Retentivity
Load Memory
Work Memory
DB
DB
Initial values
+ Actual values
DB
(with data types)
Actual values
CPU
with
STEP 7
Program
Upload in PG
Initial values
Initialize
data block
+ Actual values
DB is retentive until the
next transmission
PG  CPU
With every CPU startup (i.e.
with every STOP-RUN
transition) the DB data are
reset to the initial loading
state
SIMATIC S7
Siemens AG 2006. All rights reserved.
Date:
File:
2/8/2012
PRO1_10E.9
x
SITRAIN Training for
Automation and Industrial Solutions
Addressing Data Elements
8 Bits
7
0
Data Byte 0
DBB 0
Data Byte 1
DBW 0
Data Byte 2
DBD 0
Data Byte 3
DBX 4.1
DBD 2000
DBW 2002
DBB 2003
SIMATIC S7
Siemens AG 2006. All rights reserved.
Date:
File:
2/8/2012
PRO1_10E.10
SITRAIN Training for
Automation and Industrial Solutions
Accessing Data Elements
DB 18 "Parts"
Addr.
Name
Type
0.0
Act_Quantity
INT
2.0
FL_Aux
BOOL
4.0
Number
INT
6.0
10.0
Weight[1]
Weight[2]
SIMATIC S7
Siemens AG 2006. All rights reserved.
Traditional
Access
Fully-qualified Access
absolute
symbolic
OPN "Parts"
L
DBW0
or
L
DB18.DBW0
or
L "Parts".ACT_
Quantity
OPN DB 18
A
DBX2.0
or
A
DB18.DBX2.0
or
A "Parts".FL_Aux
REAL
REAL
OPN "Parts"
T
DBW 4
or
T
DB18.DBW4
or
T "Parts".Number
OPN
L
or
L
DB18.DBD10
or
L "Parts".Weight[2]
DB 18
DBD 10
Date:
File:
2/8/2012
PRO1_10E.11
SITRAIN Training for
Automation and Industrial Solutions
Exercise 1: Replacing Bit Memory Variables with DB Variables
SIMATIC S7
Siemens AG 2006. All rights reserved.
Date:
File:
2/8/2012
PRO1_10E.12
SITRAIN Training for
Automation and Industrial Solutions
Exercise 2: Connecting WinCC flexible Tags to DB Variables
Tags in WinCC flexible
SIMATIC S7
Siemens AG 2006. All rights reserved.
Variables in STEP7
Date:
File:
2/8/2012
PRO1_10E.13
SITRAIN Training for
Automation and Industrial Solutions
If You Want to Know More
SIMATIC S7
Siemens AG 2006. All rights reserved.
Date:
File:
2/8/2012
PRO1_10E.14
SITRAIN Training for
Automation and Industrial Solutions
Example of an ARRAY
Measuring_point
1. Measuring_point, data type Real
2. Measuring_point, data type Real
3. Measuring_point, data type Real
•
•
•
10. Measuring_point, data type Real
Array with the name "Measuring_point"
(several elements of the same data type)
Display in the Program Editor (Data Block DB 2):
SIMATIC S7
Siemens AG 2006. All rights reserved.
Date:
File:
2/8/2012
PRO1_10E.15
SITRAIN Training for
Automation and Industrial Solutions
Example of a STRUCTURE
Motor_data
Speed, data type Integer
Structure with the name "Motor_data"
(several elements
with different data types)
Rated_current, data type Real
Starting_current, data type Real
Direction, data type Bool
Display in the Program Editor (Data block DB 1):
SIMATIC S7
Siemens AG 2006. All rights reserved.
Date:
File:
2/8/2012
PRO1_10E.16
SITRAIN Training for
Automation and Industrial Solutions
Defining the Address Priority (Symbolic/Absolute)
SIMATIC S7
Siemens AG 2006. All rights reserved.
Date:
File:
2/8/2012
PRO1_10E.17
SITRAIN Training for
Automation and Industrial Solutions