device manual AS-i DP - Gateway
4 Setting up the AS-i System
4.1 AS-i power supply
A special AS-i power supply (for example AC1216) is required for operation of an AS-i system.
This power supply delivers the energy to the yellow AS-i cable and accomplishes the data decoupling
from the voltage regulator in the power supply. Standard switching power supplies would recognize
the AS-i data signals as a disturbance signal and would suppress them.
The AS-i + and AS-i – terminals are present twice on the AS-i power supply. This allows easy
connection to the AS-i 1+ and AS-i 1– terminals of AS-i DP -Gateway (or ASI 2+ and ASI 2- for the
second AS-i master system in AC1326). For the operation of a second AS-i master in AC1326 another
AS-i power supply is required causing the two systems to be galvanically separated. The AS-i masters
of AC1326 are partially supplied with voltage from the AS-i system. The single master system AC1335
is completely supplied with voltage from the AS-i system.
Caution: Most AS-i power supplies are short circuit protected. Nonetheless the power supply
should always be removed from voltage before the AS-i DP -Gateway
is
connected.
Important: The AS-i system is to be operated without grounding. The AS-i + and AS-i – lines
are to be symmetrical to the plant earth. This is accomplished by making a low
resistance connection between the shield terminal and the plant earth.
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