Baumer PosCon OXE7, Руководство по эксплуатации

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04.01.2021 15:33/adr V1.3 ANW_81125407 Frauenfeld, Switzerland
6.5
Interfaces and outputs
All sensor inputs and outputs which transmit measuring data are referred to as interfaces.
-
Analog current output, 4 … 20mA or 0 … 10V (switching)
-
Synchronization
-
Switching output push-pull
-
Alarm output push-pull
-
RS-485
6.5.1
Analog signal output
The sensor is equipped with an adaptive output. This means the sensor detects automatically whether it
should
supply current or voltage. For this purpose, the load is measured when voltage is connected: If the
load is high-impedance (>10 kOhm), the voltage output is activated, or else the current output.
To change to the other analog mode (mA or volt), the supply vVs from the sensor must be switched on
and off again.
6.5.1.1
Voltage drop
The ICC supply current from the sensor flows via the +24V line to the sensor and on the 0V line back to the
power supply unit. This ICC current supply ensures that a URL1 voltage drop occurs according to Ohm's law
at the RL1 line resistance. This URL1 voltage drop ensures that the U-
Out (0…10V) is increased as result.
This may be treated like an offset and subtracted from the measurement result. Because the resistances have
a constant value, the voltage drop varies only slightly depending on the ICC sensor current.
This effect does not occur if the I-Out (4...20mA) is used instead of the U-
Out (0…10V).
Layout:
The line resistance varies depending on the line length. In addition, the contact resistances at the plug and the
ICC supply current affect the URL1 voltage drop.
Sensor
=
≈
0V
+24V
U-Out
U
I
CC
U
RL1
Power
supply
unit
Measuring
input Line resistance R
L
R
L1
R
L2
R
L3