Yokogawa 414 Batch Controller - Manual (Page 16)

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:
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.
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.
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 the Signal Timeout is set at greater than 0, and loss of signal is detected
midway through a batch, a Flow Alarm signal is output on terminal 7. In
addition, 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, process can then be reset via the STOP switch or continued by
pressing the RUN key.
14 Operation