Siemens 2AI 2/4WIRE HF Manual page 22

Connecting
5.1 Connecting measuring sensors
Connecting measuring encoders to analog inputs
There can only be a limited potential difference U
lines of the input channels. To ensure that the permitted value is not exceeded, you must
take different steps depending on the whether the encoders are isolated or non-isolated. The
steps you have to take are described in this chapter.
Abbreviations used
The meanings of the abbreviations in the figures below are as follows:
M+:
M-
M
L+
U
CM
U
ISO
22
Measuring line (positive)
Measuring line (negative)
Ground connection
Rated load voltage 24 V DC
Potential difference between inputs and reference potential of the measuring
circuit M
ANA
Potential difference between M
(common mode) between the measuring
CM
and central grounding point
ANA
2 AI I 2/4WIRE HF analog electronic module (6ES7134-4MB02-0AB0)
Manual, 04/2007, A5E01076111-01