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Flow-X─ Function Reference
Flow-X IO Functions - fxPulseInput
fxPulseInput
The 'fxPulseInput' function is meant for a flow meter that provides a single or a dual pulse output
signal. Each flow module supports either 1 single or 1 dual pulse input.
A dual pulse signal is a set of two pulse signals ('pulse trains') A and B that originate from the same flow
meter. The two pulse trains are similar but shifted in phase (typically 90°).
The primary purpose of the dual signal is to allow for pulse integrity checking. Added or missing pulses
on either pulse train are detected and corrected for and simultaneous noise pulses are rejected.
The function provides detailed information on the raw, corrected and bad pulses for both channels and
for both the forward and reverse flow direction.
The phase shifted pulse train signal also allows for automatic detection of flow direction. Each A pulse
is followed by a B pulse within a time period (
t) in case the flow runs in the forward direction. In case
the flow runs in the reverse direction, the opposite is the case, i.e. each B pulse is followed by an A
pulse within the same time period
t.
A
B
t
Channel B lags channel A
The function also provides the option to output the raw pulse signals, which is useful in case a separate
flow computer is used for proving purposes. The proving flow computer takes the pulse output from
the flow computer that processes the meter on prove to perform prove measurements including
double chronometry if required. The prover output signal is generated at 20 MHz, the same frequency
at which the raw pulse input signals are sampled.
Compliance
ISO 6551:1982, Petroleum liquids and gases -- Fidelity and security of dynamic measurement -- Cabled
transmission of electric and/or electronic pulsed data
Note: The Flow/X series of flow computers provides Level A pulse security as defined in ISO 6551,
which means that bad pulses are not only detected (level B) but also corrected for.
Function inputs
Remark
EU
SW tag
Range
Default
Name
Optional tag name, tag description
and tag group
Index
Index number. Always 1.
INDEX
1..1
1
Channel A
Input channel number for pulse A
0 disables the entire function
CHANA
0..16
0
Channel B
Input channel number for pulse B
Enter 0 in a case of single pulse
input
CHANB
0..16
Input
Channel A
+ 1
Pulse fidelity
threshold
All pulse fidelity checking will be
disabled when the corrected pulse
frequency is below the 'Pulse
fidelity threshold'
Enter a 0 to disable this
functionality (the default value)
Hz
FRQTHD
0..1e5
0
Error pulses limit
When the total number of missing
pulses, added and simultaneous
pulses for either channel becomes
larger than this value, the status
becomes 'Error Pulses'
The value 0 disables the error
pulses limit check.
ERRLIM
0..1e99
0
Missing pulses
limit
When the total number of missing
pulses on channel A or B becomes
-
MISLIM
0..1e99
0
Summary of Contents for flow-x
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