ETAS ES930.1 - Fig. 4-1 Thermo Channels TH1 to TH4; A;D Converter; Cold-Junction Compensation with A;D Converter; Overview

ETAS Thermo Channels ("TH1-4" Connections)
ES930.1 - User Guide 29
4 Thermo Channels ("TH1-4" Connections)
The ES930.1 is equipped with four mini-TC sockets ("TH1" to "TH4") for the con-
nection of thermocouples of type K.
4.1 Assemblies of the Thermo Channels
4.1.1 Overview
Fig. 4-1 Thermo Channels "TH1" to "TH4"
The four thermo channels "TH1" to "TH4" of the ES930.1 feature an identical
design. Each channel consists of the following assemblies (see block diagram
in
Fig. 4-1 on page 29):
• Cold-junction compensation with A/D converter
• A/D converter
• Open TC Detection (Open Thermocouple Detection)
The functionality of all thermo channels can be configured separately.
4.1.2 Cold-junction Compensation with A/D Converter
The integrated Mini-TC sockets for connecting the thermocouples consist of
the same combination of materials as the thermocouples (NiCr and Ni) to
achieve high accuracies across the entire temperature range.
The ES930.1 uses a common cold-junction compensation for the four thermo
channels. Measuring the cold-junction is done together for all channels using a
PTC (PT1000) that is installed close to the material transition in the module.
The construction ensures that the measurement result is affected only by a few
tenths of a Kelvin, even in case of fast changes of the ambient temperature or
uneven temperature distribution.
The signal of the cold-junction compensation is digitized by an A/D converter
with a resolution of 24 bit and provided to the measurement unit.
4.1.3 A/D Converter
The A/D converters of the thermo channels have a resolution of 24 bit. The
maximum measuring range is -200
°C to +1372 °C and corresponds to the
measuring range of thermocouples of type K.
24 Bit A/D
Converter
.
.
.

Cold
Junction
Thermo Channel n
Measure-
ment
Unit
Open TC
Detection
24 Bit A/D
Converter
Diagnosis
Unit