Siemens Simatic S7-300 CPU 31xC Series Installation And Operating Instructions Manual page 248

Glossary
Fast Ethernet
Fast Ethernet describes the standard with which data is transmitted at 100 Mbps. Fast
Ethernet uses the 100 Base-T standard.
FB
See Function block
FC
See Function
Flag bits
Flag bits are part of the CPU's system memory. They store intermediate results of
calculations. They can be accessed in bit, word or dword operations.
Flash EPROM
FEPROMs can retain data in the event of power loss, same as electrically erasable
EEPROMs. However, they can be erased within a considerably shorter period of time
(FEPROM = Flash Erasable Programmable Read Only Memory). They are used on Memory
Cards.
Force
The Force function can be used to assign the variables of a user program or CPU (also:
inputs and outputs) constant values.
In this context, please note the limitations listed in the
in the chapter entitled Test functions, diagnostics and troubleshooting in the S7-300
Installation manual
Function
According to IEC 1131-3, a function (FC) is a --> code block without --> static data. A
function allows transfer of parameters in user program. Functions are therefore suitable for
programming frequently occurring complex functions, e.g. calculations.
Function block
According to IEC 1131-3, a function block (FB) is a --> code block with --> static data. An FB
allows the user program to pass parameters. Function blocks are therefore suitable for
programming frequently occurring complex functions, e.g. controls, mode selections.
Functional ground
Grounding which has the sole purpose of safeguarding the intended function of electrical
equipment. With functional grounding you short-circuit interference voltage which would
otherwise have an unacceptable impact on equipment.
Glossary-6
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Overview of the test functions section
S7-300, CPU 31xC and CPU 31x: Installation
Operating Instructions, Edition 08/2004, A5E00105492-05