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5.3
Digital output signals
The Flow Transmitter has two digital output signals, Output2 and Output3. Voltage supplies
are required for output signals.
The outputs are isolated from other parts of the electronics by optocouplers. Furthermore, the
outputs are protected against overload by a zener diode and a current-limiting resistance,
R
. R
is about 25 Ohms at normal load (max. 100 mA). At overload, the R
PTC
PTC
rapidly thus limiting the current to about 16 mA.
If an output has been overloaded, the current
must be completely switched off for some
seconds, by switching off the power supply to
the Flow Transmitter, before the output can
be normally loaded again.
A voltage drop of up to 1.0 V may occur when
the output is switched ON. This should be
noted when connecting to low voltage exter-
nal equipment.
In case of wrong polarization of the connection, the signal acts as a constant ON signal.
5.3.1
Output2
The pulse output signal from Output2 has a pulse width of 40 ms. The frequency is continu-
ously variable from 0-10 Hz.
40 ms
Pulse signal Output2
Example of electrical connection of electro-mechanical counters.
Counter specification:
Supply voltage:
Power consumption:
Counting frequency:
ON-time:
OFF-time:
Manual
20-40 V DC
Max. 2.5 W
Min. 10 Hz
Typ. 40 ms
Min. 60 ms
Flow Transmitter, PD 340
Q
FLOW TRANSMITTER
+
5
Output 1
-
6
+
3
Output 2
-
4
502 010 05
will rise
PTC
R PTC
+
D zener, 51 V
-
551 105 01
COUNTER
551 106 01
21/55
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