
414L-M-V3
3.2.2 Signal Timeout
The Signal Timeout period defines a time interval which is used to detect if
the flow has stopped. If there is no signal input for a time greater than the
Signal Timeout period the flow is deemed to have stopped. A Signal
Timeout period has two functions:
Ÿ
To detect the loss of signal midway through a batch when the
relays are energised. In this case, the Batcher will enter a Flow
Alarm condition and de-energise the relays.
Ÿ
After the preset batch quantity has been reached and the
relays de-energised, some overrun of flow may occur due to
slow valve closure, etc. In this case, the Signal Timeout is
used to determine when the flow has ceased and thereby
accurately determine the amount of overrun.
It is recommended that Signal Timeout periods are kept fairly short, but
long enough such that the period is significantly longer than the time
period between successive input pulses from the flowmeter at the
minimum flowrate.
The instrument enables the user to program a time interval of up to 99
seconds to detect an absence of signal input.
If the Signal Timeout is set to 0,
this function is disabled.
Flow Alarm
If a Signal Timeout is set at greater than zero and loss of signal is
detected midway through a batch, a Flow Alarm signal is output on
terminal 7. In ddition, both relays are de-energised. The Flow Alarm
output and condition is maintained until acknowledged by pressing the
STOP switch. The alarm condition is also signalled to the operator by the
flashing STOP LED. Once acknowledged, the process can then be reset via
the STOP switch or continued by pressing the RUN key.
18
Operation
Содержание 414L
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