Siemens RUGGEDCOM RM1224, Руководство по эксплуатации

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Connecting up
3.5 Digital input/output
RUGGEDCOM RM1224
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Operating Instructions, 10/2016, RC1260-EN-02
grounded at one defined point. Here, once again the grounding is implemented with the
lowest leakage resistance to ground in the vicinity of the power feed-in.
With automation components, functional ground also ensures interference-free operation of
a controller. Via the functional ground, interference currents coupled in via the connecting
cables are discharged to ground.
In terms of the large-area and low impedance implementation, a functional ground set up for
this purpose generally also meets the requirements of protective earth. On the other hand,
protective earth does not always meet the requirements of functional ground. In general
while the connection for protective earth is always low resistance, it is not necessarily low
impedance.
The resistance of a connection for protective earth must always be as small as possible to
divert fault currents safely to ground. The length of a protective earth cable can therefore be
several meters (m) long, without seriously impairing this effect. For a functional ground for
diverting HF disturbances, this cable does however have impedance and is therefore not
suitable.
3.5 Digital input/output
The digital input/output (relay contact) is a floating switch with which error/fault states can be
signaled by breaking the contact.
CAUTION
Damage due to voltage being too high or too low
The voltage at the digital input/output must not exceed 30 VDC and not fall below -30 VDC,
otherwise the digital input/output will be destroyed.