Connecting Sensors To The 466 Analog Input Module - Siemens S5-155U System Manual

+
U E2
-
U E1
U E1/2 : Input Voltage
U ISO : Potential Difference
: Equipotential: this is established by the sensor reference potential
(external reference potential)
Figure 9-31 Connecting Sensors to the 466 Analog Input Module (Measurement with Respect to Ground)
Differential measurement
System Manual
C79000-B8576-C109-03
The following figure shows the connection of sensors to the module.
For measurement with respect to ground, all the M- connection points
are interconnected internally on the module.
Analog Input Module
M +
M +
MUX
+
M -
-
U ISO
The differential measurement is a method of compensating for
interference on the line. Each signal source is assigned its own signal
reference line. The differential measurement between signal line and
signal reference line thus compensates for the interference acting on
both lines.
You must also short-circuit the unused channels with this measuring
method (jumper between M+ and M-).
Differential measurement is required:
• • if the sensors are at different potentials;
• • if various signal sources are not close to each other;
• • if there is a need to measure signals with high precision,
• • and when a high level of interference is expected.
The 466 Analog Input Module
0 V Bus
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