11
PULSE:
Enter the number of pulses per unit volume
required. This figure can be adjusted to suit the
application and the flow range required from the meter.
The maximum output frequency is 1000 Hz. So care
must be taken to ensure that this pulse rate is not
exceeded.
E.g. 10 L/min at 1000 Hertz equals (1000x60)/10 = 6000 P/L
Therefore 6000 pulses per litre is the maximum resolution
for 10 litres per minute assuming maximum frequency
output. If the meter is being used up to 5 L/Min the pulse
output and so resolution could be doubled to 12000 P/L.
SINGLE FLOW ALARM:
Checking this option opens up input boxes for
THRESHOLD; LATCHING and INVERT
Set the
Threshold
to the flow value you require the
transistor to operate. The logic of operation can be
adjusted with the INVERT check box (see left).
The
Latching
box gives the user three options of None;
High Threshold and Low Threshold.
• “None” will cause the alarm to be triggered when the
threshold flow is met. The alarm state will then reset
in accordance with the user set Hysteresis.
• “High Threshold” will cause an alarm signal to Latch
on when flow is seen above the set value
• “Low Threshold” will cause an alarm signal to Latch
on when flow is seen below the set value
Hysteresis (%): This is used when Latching is Set to
NONE to prevent “fluttering” of the alarm signal when
flow is around the threshold level.
LATCHED
alarms will remain Active and the Local Display will show “LATCH” until they
are reset. RESET LATCH ALARMS by either a signal Input on one of the other Input/
Output PINS, or by Pressing and Holding the Right Hand Button on the Local Display
on the Flow meter for 3 seconds.
Note the alarm points are driven by the display value on the “flow reading” screen. Any
changes to the filter value of the display will affect the response time of the alarm points
so there are two adjustable parameters to ensure “fluttering” does not happen with
small flow fluctuations - response time and hysteresis.
INVERT – This Check box allows the user to invert the operation of the signal
•
Checked – Alarm output logic HIGH
For details see the Alarm logic table or hover mouse over the set point to see the action
of the output with the chosen settings.