Siemens Technical Terms

Otherwise known as Siemens speak. Here's a list of Siemens specific abbreviations and their meanings.


Term Description Explanation
C7 Combo PLC/HMI system A PLC and screen in one package
CFC Continuous Function Chart Optional programming language
CP Communication Processor Modules used for special communication protocols
DB Data Block Memory storage areas for user data
FB Function Block A function with it's own data block
FBD Function Block Diagram Standard programming language
FC Function Call Called progammed blocks
FM Function Module Modules with special functions (e.g. positioning)
GSD Generic Station Description Files used for Profibus descriptions
HiGraph   Optional programming language
IM Interface Module Modules to connect remote racks
LAD Ladder Logic Diagram Standard programming language
M7 Programmable modules A module with processing capabilities
MMC Micro Memory Card Compact plug-in memory card
MPI Multi Point Interface Standard communication protocol
OB Organization Block Blocks for user programs based on different operating system events.
OP Operator Panel Simple display with or without buttons
PCS Process Control System Software for the entire process chain
PG Programming Terminal Dedicated Siemens device - basically a PC
PPI Point to Point Interface Serial RS-232 communication
Profibus DP Profibus Decentral Peripherals Networking protocol used for factory automation
Profibus PA Profibus Process Automation Networking protocol used for process automation
S7   SIMATIC Step 7 product line
SCL Structured Control Language Optional programming language
SFB System Function Block Integrated FB for CPU information
SFC System Function Call Integrated FC for CPU information
SM Signal Module Standard Input/Output modules
STL Statement List Text based programming language
TP Touch Panel Touch screen display
UDT User-Definded Data Type Special data structures defined by the user
VAT Variable Access Table Tables used to monitor/modify values in the PLC


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I have a question about the PCS 7!
I am learning a manual from SIEMENS which they describe some functions blocks in PCS 7 With the CFC editor !
my question are :

1 what is the difference between PCS7 and STEP7?

2. if the blocks functions are changed if I would use STEP 7 with the CFC library ?

3. any person does you use the CM 104 gateway from SIEMENS ?


What is the differance between instance databloc & sheard data block
Please help.