Glossary
Glossary-4
Programmable Logic Controllers S7-300 Module Data
A5E00105505-03
Equipotential bonding
Electrical connection (equipotential bonding conductor), which brings the bodies
of electrical resources and foreign conductive bodies to an identical or approxi-
mately identical potential in order to avoid interfering or hazardous voltages be-
tween these bodies.
FREEZE
Parameter in STEP 7 for position detection module SM 338; POS-INPUT. The
FREEZE function is a control command for freezing current encoder values of
the SM 338 to the instantaneous value.
Ground
The conductive ground whose electric potential can be set equal to zero at every
point.
In the proximity of grounding electrodes, the ground can have a potential differing
from zero. The term “reference ground” is frequently used to describe such cir-
cumstances.
Ground, to
To ground means connect an electrically conductive part by means of a ground-
ing system to the grounding electrode (one or more conductive parts having a
very good contact to ground).
Hardware interrupt
A hardware interrupt is triggered by interrupt-triggering modules as a result of a
certain event in the process (overshooting or undershooting of a limit value; a
module has completed the cyclic conversion of its channels).
The hardware interrupt is reported to the CPU. In accordance with the priority of
this interrupt, the →Organization block assigned to it is scanned.
Hold last value (LWH)
The module retains the last value read out before STOP mode.
Input delay
Parameter in STEP 7 for digital input modules. The input delay is used to sup-
press injected interference. Interfering pulses from 0 ms to the set input delay
are suppressed.
The set input delay is subject to a tolerance, which can be taken from the techni-
cal specifications of the module. A high input delay suppresses long interfering
pulses, whereas a low input delay suppresses short ones.
The permissible input delay depends on the length of the cable between the en-
coder and the module. For example, a high input delay has to be set for long un-
shielded supply conductors to the encoder (longer than 100m).
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