Endress+Hauser Proline Prowirl 73 - Page 124

Description of device functions Proline Prowirl 73
124 Endress+Hauser
OUTPUT SIGNAL Prerequisite
The function is only available if FREQUENCY was selected in the OPERATION MODE
function (ä 122).
Description
For selecting the polarity of the frequency.
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!
In the case of passive output configuration, the output signal levels of the frequency
output depend on the external wiring (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 resistor. In the quiescent state (at zero
flow), the output signal level at the terminals is 0 V.
A0004687
m
Open collector
n
Pull-up resistor
o
Transistor activation in "POSITIVE" quiescent state (at zero flow)
p
Output signal level in quiescent state (at zero flow)
In the operating state (flow present), the output signal level changes from 0 V to a
positive voltage level.
A0001975
(Continued on next page)
Function description, PULSE, FREQUENCY, STATUS group
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