Siemens Simatic S7-400 - Manual (Page 612)

Glossary
Glossary-6
S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07
Equipotential bonding
An electrical connection (equipotential bonding conductor) that brings the bodies
of electrical resources and foreign conductive bodies to an identical or
approximately identical potential in order to avoid interfering or hazardous
voltages between these bodies.
External load memory
³
Memory card
FB
³
Function block
FC
³ Function
FEPROM
In their ability to retain data in the event of a power failure (even without a backup
battery), FEPROMs (flash erasable programmable read only memories) are the
equivalent of the electrically erasable
³
EEPROMS, but can be erased
considerably more quickly.
Fiber-optic cable
A fiber-optic cable is a transmission medium made of glass fiber or plastic.
Fiber-optic cables are resistant to electromagnetic faults and they make fast data
transfer rates possible.
Force
The “Force” function overwrites a variable (for example, memory marker, output)
with a value defined by the user.
At the same time, the variable is assigned write protection so that this value
cannot be modified from any point (including from the STEP 7user program). The
value is retained after the programming device is disconnected.
Write protection is not canceled until the ”Unforce” function is called and the
variable is written again with the value defined by the user program.
During commissioning, for example, the “Force” function allows certain outputs to
be set to the ”ON” state for any length of time even if the logic operations of the
user program are not fulfilled (for example, because inputs are not wired).
FREEZE
Control command. The inputs of the ³ DP slaves are frozen to the current value.