
414L-M-V3
3.3 SINGLE AND QUADRATURE INPUTS
In most industrial flowmetering applications, a frequency producing
flowmeter has only a single output.
However, in many custody transfer applications, it is a requirement that
the flowmeter has two outputs so that the integrity of the signal can be
assured. This usually requires a turbine meter to have two coils, or a
positive displacement meter to have two pulse units.
The Model 414L can interface to flowmeters fitted with two sensors
and connections to the flowmeters are outlined in Section 7.1.1.
The quadrature input has two functions.
1 To detect a difference in the number of pulses from each input
during delivery.
The instrument will alarm if the pulse difference (since reset)
exceeds 1 in 1000 pulses. When an alarm condition exists the
totals will cease counting and will freeze at the last total prior to
the alarm.
On detection of the alarm condition, the alarm output on
terminal 7 w ill go low (energise), the output relays will de-
energise and the stop LED will flash, indicating that the batch can
be continued by pressing the RUN key or aborted using the STOP
key. The display will also periodically flash the error message,
ERR 13.
2 Bi-directional Flow.
The 414L has the ability to detect forward and reverse flow.
The inputs must be connected with channel 1 being the 90°
flow signal and channel 2 being the 0° signal. For
forward/reverse detection to function correctly, there must be
clear definition of the input signals.
22
Operation
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