Siemens Simatic S7 Series System Manual

Programming concepts
5.2 Elements of the user program
S7-200 SMART
88 System Manual, 09/2015, A5E03822230-AC
● Interrupt routines are optional elements of your program that react to specific interrupt
events. You design an interrupt routine to handle a pre-defined interrupt event. Whenever
the specified event occurs, the CPU executes the interrupt routine.
The interrupt routines are not called by your main program. You associate an interrupt
routine with an interrupt event, and the CPU executes the instructions in the interrupt
routine only on each occurrence of the interrupt event.
Note
Because it is not possible to predict when the CPU might generate an interrupt, it is
desirable to limit the number of variables that are used both by the interrupt routine and
elsewhere in the program.
Use the local
variable table of the interrupt routine to ensure that your interrupt routine
uses only the temporary memory and does not overwrite data used somewhere else in
your program.
There are a number of programming techniques you can use to ensure that data is
co
rrectly shared between your main program and the interrupt routines. Refer to the
descriptions of the
Interrupt instructions (Page 282).
● Other blocks contain information for the CPU. You can choose to download these blocks
when you download your program:
– System Block: The system block allows you to configure different hardware options for
the CPU.
– Data Block: The DB stores the initial values for different variables (V memory) used by
your program.

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.