Table of Contents
Advertisement
Connecting
5.1
Connecting measuring sensors
Introduction
You can connect resistances as measuring sensors to the analog input module.
In this chapter you will find out how to connect the measuring sensors and what to watch for
when doing so.
Lines for analog signals
You should use shielded and twisted-pair lines for the analog signals. This reduces the effect
of interference. You should ground the shield of the analog lines at both ends of the line. If
there are differences in potential between the ends of the line, a compensating current flows
via the shield that can interfere with the analog signals. If this is the case, you should only
ground the shield at one end of the line.
Analog input modules
In the case of the analog input modules there is electrical isolation:
● Between logic and backplane bus.
● Between load voltage and the channels
Abbreviations used
The meanings of the abbreviations in the figures below are as follows:
M +
M -
I
C
I
C
U
CM
U
ISO
2/4AI RTD ST analog electronic module (6ES7134-4JB51-0AB0)
Manual, 07/2008, A5E01076865-02
– Isolation: No link between M
Note
Ensure that this potential difference U
Measuring line (positive)
Measuring line (negative)
+
Constant-current cable (positive)
-
Constant-current cable (negative)
Potential difference between inputs
Potential difference between M- and central grounding point
and the central grounding point (U
ANA
does not exceed the permitted value.
ISO
5
)
ISO
27
Advertisement
Table of Contents
