Pulse Output - BASI BFM921 User Manual

Electromagnetic Flowmeter BFM921
Mode h) with non-zero hysteresis:
Mode k) with non-zero hysteresis:
Mode l) with non-zero hysteresis:
Qf value represents flowrate for frequency 1000 Hz and can be set independently to the nominal diameter of
the sensor. Values PF1, PF2 and H are described in the chapter "LIMITS".
5.1.2.2 Fixed frequency
Item allows setting frequency in the frequency mode m) (Fixed). The range is between 10 and 12000 Hz.
Fixed frequency mode is suitable for testing purposes.
5.1.2.3 Flowrate for 1kHz (Qf 1kHz)
Item allows setting the Qf constant. Qf represents the flowrate for the frequency 1000Hz and can be set
independently to the nominal diameter of the sensor. The range of Qf value is proportional to the flowrate
range of range of the flowmeter (DN diameter).
5.1.3

Pulse output

Pulse output is formed by a galvanically isolated NPN transistor
switch. Voltage drop on the switch is 1 V in HI state. Maximum
switched voltage is 50 V. Maximum switched current should not
exceed 100 mA. Positive output is on terminal PLS, negative
output is on terminal COM. Width of the impulse can be set.
Maximum frequency of impulse output is limited by the impulse
width. For the shortest impulse 2.5 ms there is maximal
frequency of 200 Hz.
Note 1: Frequency, impulse
galvanically connected to each other and galvanically
isolated from other electronic circuits.
Note 2: Active pulse output uses the power supply of the
current output. Total current consumption from this
power supply must be less than 40 mA. Active
frequency output is galvanically connected to current
output.
Note 3: In case of using this output as a passive, external source
and current limiting is necessary.
5.1.3.1 Mode
Pulse output can be programmed in one of the following modes:
a) Off
b) Positive Flow
c) Negative Flow
d) Absolute Flow
e) On Positive
26
OFF
ON
OFF
ON
OFF
ON
and status outputs
output is not active (HI state).
1 impulse is generated every time when volume Qp has flown in positive
direction.
1 impulse is generated every time when volume Qp has flown in negative
direction.
1 impulse is generated every time when volume Qp has flown in any
direction.
output is HI in case of negative flow and LO in case of positive flow.
PF1 PF1+H PF2-H PF2
PF2-H PF2
PF2-H PF2
are
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