Siemens Simatic S7 Series User Manual

15
In the following example, the program segments perform the
same function.
Network 1
Network 2
I0.0 I0.1 Q0.0
I0.4
I0.5
Q0.0
Network 1
LD
A
=
I0.0
I0.1
Q0.0
LD
O
=
I0.4
I0.5
Q0.1
Network 2
AND
I0.0
I0.1
Q0.0
OR
Q0.1
I0.4
I0.5
Network 1
Network 2
Statement List (STL) Function Block Diagram (FBD) Ladder Logic (LAD)
In addition to LAD, STL, and FBD, multiple other types of
programming languages are used for PLCs. Each type of
programming has its advantages and disadvantages. Factors
such as application complexity, types of programming available
for a specific PLC model, and user standards and preferences
determine which type of programming is used for an
application.
PLC Scan The PLC program is executed as part of a repetitive process
referred to as a scan. A PLC scan starts with the CPU
reading the status of inputs. Next, the application program is
executed. Then, the CPU performs internal diagnostics and
communication tasks. Finally, the CPU updates the status of
outputs. This process repeats as long as the CPU in the run
mode. The time required to complete a scan depends on the
size of the program, the number of I/Os, and the amount of
communication required.
PLC Scan
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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.