Siemens SIMATIC S7-400 Reference Manual page 452

Glossary
S7 basic communication
Communication functions integrated in the CPU of SIMATIC S7/C7 that can be called up by
the user. These functions are called in the user program with → system functions. The user
data length is up to 76 bytes (small amounts of data). S7 basic communication is implemented
over → MPI.
S7 communication
Communication functions integrated in the CPU of SIMATIC S7/C7 that can be called up by
the user. These functions are called in the user program with → system function blocks. The
user data length is up to 64 Kbytes (large amounts of data). S7 communication provides a
network-independent interface between devices of the types SIMATIC S7/C7 and PG/PC.
Segment
→ Bus segment
Shunt
Conductor connected in parallel in electric circuits.
Signal module
Signal modules (SMs) form the interface between the process and the automation system.
There are input modules, output modules, input/output modules (in each case, digital and
analog)
Smoothing
Parameter in STEP 7 for analog input modules. The measured values are smoothed by digital
filtering. It is possible to select between no, weak, medium and strong filtering for each
individual module. The stronger the smoothing, the higher the time constant of the digital filter.
Standard communication
Communication over standardized protocols such as PROFIBUS-DP, PROFIBUS-FMS.
Static data
Static data is data that is used only within a → function block. This data is stored in an instance
data block belonging to the function block. Data stored in this way is retained until the next
function block call.
Substitute value
Substitute values are values that are output to the process or are used in the user program
instead of a process value if a signal output module is defective.
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S7-400 Automation System Module Data
Reference Manual, Ausgabe 11/2016, A5E00850736-08