10 Group PULSE/FREQUENCY OUTPUT Device Functions Proline Promass 80
32 Endress+Hauser
OUTPUT SIGNAL
! Note!
This function is not available unless the FREQUENCY setting was selected in the
OPERATION MODE function.
In this function the output can be configured in such a way that it suits an external
totalizer.
Options:
PASSIVE - POSITIVE
PASSIVE - NEGATIVE
Factory setting: PASSIVE - POSITIVE
Explanation
• PASSIVE = power is supplied to the frequency output by means of an external power
supply.
Configuring the output signal level (POSITIVE or NEGATIVE) determines the quiescent
behavior (at zero flow) of the frequency output.
The internal transistor is activated as follows:
• If POSITIVE is selected, the internal transistor is activated with a positive signal level.
• If NEGATIVE is selected, the internal transistor is activated with a negative signal
level (0 V).
!Note!
With the passive output configuration, the output signal levels of the frequency output
depend on the external circuit (see examples).
Example for passive output circuit (PASSIVE)
If PASSIVE is selected, the frequency output is configured as an open collector.
A0001225
m = Open Collector
n = External power supply
!Note!
For continuous currents up to 25 mA (I
max
= 250 mA / 20 ms).
Example for output configuration PASSIVE-POSITIVE:
Output configuration with an external pull-up resistance.
In the quiescent state (at zero flow), the output signal level at the terminals is 0 V.
A0004687
m = Open collector
n = Pull-up resistance
o = Transistor activation in “POSITIVE” quiescent state (at zero flow)
p = Output signal level in quiescent state (at zero flow)
In the operating status (flow present), the output signal level changes from 0 V to a
positive voltage level.
A0001975
(continued on next page)
Function description PULSE/FREQUENCY OUTPUT
1
5
8 3
7
+
-
=
U =30VDC
max
m
n
U =30VDC
max
+
U (V)
t
U (V)
t
o
p
m
n
U (V)
t
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