ABB AC500 PLC - Connection of Resistance Thermometers in 2-wire Configuration

Generally, analog signals must be laid in shielded cables. The cable shields
must be earthed at both sides of the cables. In order to avoid unacceptable
potential differences between different parts of the installation, low resistance
equipotential bonding conductors must be laid.
Only for simple applications (low electromagnetic disturbances, no high require-
ment on precision), the shielding can also be omitted.
The following figure shows the electrical connection of the module:
2.0
1.0
I0+
I0–
2.1
1.1
I1+
I1–
2.2
1.2
I2+
I2–
2.3
1.3
I3+
I3–
AGND
UP
ZP
1.8 2.8 3.8 4.8
1.9 2.9 3.9 4.9
+24 V
0 V
PTCPTC
8 analog inputs
for 0...10 V
–10 V...+10 V
0/4... 20 mA
Pt100 / Pt1000
Ni1000
digital signals
2.4
1.4
I4+
I4–
2.5
1.5
I5+
I5–
2.6
1.6
I6+
I6–
2.7
1.7
I7+
I7–
4.0
3.0
I8+
I8–
4.1
3.1
I9+
I9–
4.2
3.2
I10+
I10–
4.3
3.3
I11+
I11–
8 analog inputs
for 0...10 V
–10 V...+10 V
0/4... 20 mA
Pt100 / Pt1000
Ni1000
digital signals
4.4
3.4
I12+
I12–
4.5
3.5
I13+
I13–
4.6
3.6
I14+
I14–
4.7
3.7
I15+
I15–
AGND
Attention:
By installing equipotential
bonding conductors between
system, it must be made sure
that the potential difference
between ZP and AGND never
the different parts of the
can exceed 1 V.
Attention:
The process voltage must be
included in the earthing concept
of the control system
(e.g. earthing the minus pole).
The modules provide several diagnosis functions Ä Chapter 1.5.2.2.1.7 “Diagnosis”
on page 466.
Connection of Resistance Thermometers in 2-wire Configuration
When resistance thermometers (Pt100, Pt1000, Ni1000) are used, a constant current must flow
through them to build the necessary voltage drop for the evaluation. For this, the module AI523
provides a constant current source which is multiplexed over the 8 analog channels.
Device Specifications
I/O Modules > Analog I/O Modules
2019/04/17 3ADR010121, 13, en_US 455