Siemens Simatic S7 Series System Manual

PLC concepts
4.2 Accessing data
S7-200 SMART
System Manual, 09/2015, A5E03822230-AC
65
Figure 4-4 Accessing the accumulators
SM (special memory)
The SM bits provide a means for communicating information between the CPU and your
user program. You can use these bits to select and control some of the special functions of
the CPU, such as: a bit that turns on for the first scan cycle, a bit that toggles at a fixed rate,
or a bit that shows the status of math or operational instructions. You can access the SM bits
as bits, bytes, words, or double words:
Table 4- 12 Absolute addressing of SM memory
Bit:
SM [byte address].[bit address]
SM0.1
Byte, Word, or Double Word: SM [size][starting byte address] SMB86,
SMW300,
SMD1000
For more information, see the descriptions of the SM bits (Page 665).

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.