Electrical Connection - IFM Electronic AS-interface AC2220 Notice De Montage

Electrical connection

Connection of a 2-wire Pt100 element to the AS-i module
AS-i module
1+ ... 4+
1- ... 4-
Connection of a 4-wire Pt100 element to the AS-i module
AS-i module
1+ ... 4+
1- ... 4-
It is necessary to connect at least one Pt100 sensor before
switching on the AS-i slave to start the A/D converter, otherwise
the LEDs I1 to I4 flash at a frequency of about 5Hz.
Important notes regarding Pt100 measurements:
In the Pt100 measurement principle, very low currents flow in the mea-
suring electronics. It must be ensured that additional resistance (cables,
contact and transition resistance, loose contacts, etc.) is avoided in the
measuring circuit.
Only this way is a precise measurement, for which these modules are
designed, possible.
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Pt100 element
Pt100 element
S+
S-
The 1+ ... 4+ terminals are intercon-
nected in the module.
4-wire Pt100 sensors supply more
exact results than 2-wire sensors
provided that the wire resistance is
the same.
The changeover between 2 and 4-
wire sensors is made via the para-
meter bit P3.
The 1+ ... 4+ terminals are intercon-
nected in the module.