Siemens Simatic S7 Series System Manual

Programming concepts
5.6 Variable table
S7-200 SMART
106 System Manual, 09/2015, A5E03822230-AC
Viewing the variable table
To view the variable table for the POU selected in the program editor, select "Variable table"
from the Component drop-down list in the Windows area of the View menu.
Note
You can put the variable table on the
quick access toolbar (Page 87) for easy access.
Making assignments in the variable table
Note
Make the assignments in the variable table before
using local variables in your program.
When you use symbolic names in your program, the program editor checks first the Local
Variable Table of the appropriate POU, and then the symbol table. If the symboli
c name is
undefined in both places, the program editor treats it as an undefined global symbol which is
indicated by a green wavy underline. The program editor does not automatically re
-read the
variable table and make corrections to your program logic. If
you later make a data type
assignment that defines that symbolic name (in the local variable table), you must manually
insert a pound symbol (#) in front of the name, like this: #UndefinedLocalVar (in the program
logic). For this reason, declaring the var
iables prior to usage minimizes the programming
effort.
The maximum limit of input/ output parameters for each subroutine call is 16. If you attempt
to download a program that exceeds this limit, STEP
7-Micro/WIN SMART returns an error.

Siemens Simatic S7 Series Specifications

General

CPU	Varies by model (e.g., S7-300, S7-400, S7-1200, S7-1500)
Communication Interfaces	PROFIBUS, PROFINET, Ethernet, MPI
Programming	TIA Portal, STEP 7
Programming Languages	LAD, FBD, STL, SCL, GRAPH
I/O Modules	Digital, Analog, Specialty modules available
Operating Temperature	0°C to 60°C (standard models)
Mounting	DIN rail mounting
Operating Voltage	24V DC or 120/230V AC (varies by model)
Protection Class	IP20 (standard models)
Memory	Varies depending on the S7 model. Includes work memory (RAM) for program execution, load memory (EEPROM or Flash) for program storage, and system memory for operating system functions. Memory sizes range from kilobytes to megabytes.