Yokogawa Data Acquisition with PID Control CX2000 User Manual
Page 76
1-64
IM 04L31A01-01E
• Delay lower limit alarm
An alarm occurs when the measured/computed value remains below the alarm value
for the specified time (delay).
Delay upper limit alarm example (T is the specified delay)
Alarm release
Alarm occurrence
T
X1
X2
X3
X4
T1
Measured value or
computed value
Alarm setting
• Alarm does not occur at T1, because the time is shorter than the specified delay (T).
• The input exceeds the alarm value at X2, but the alarm occurs at X3 at which the
specified delay period elapses (the time when the alarm occurs is the time at X3).
• The input falls below the alarm value at X4 and the alarm is released.
Note
The following special operations are available for the delay upper/lower limit alarm.
•
When a delay alarm is set on a computation channel and the computation is stopped
If the computation is stopped in a condition in which the computed value is exceeding the
alarm setting, the alarm is turned ON after the specified period (delay period) elapses.
Alarm occurrence
T
Computed
values
Stop computation
Alarm setting
•
Delay alarm when a power failure occurs
Alarm detection is reset upon a power failure. It restarts the operation after the power recovers.
Power failure
occurrence/recovery
Power failure
occurrence/recovery
T
T
T
Alarm
On
Off
On
Off
On
Off
Measured value or
computed value
Alarm setting
:Off
•
Operation when the alarm setting is changed
• When a new delay alarm is set
The alarm detection starts at the time the alarm is set. It is unaffected by the conditions
existing before the alarm is set.
• If the alarm setting of a preexisting delay alarm is changed
• If an alarm is not occurring at the time of the change, alarm detection starts at the
new setting.
• If an alarm is occurring at the time of the change and the alarm type is set to delay
upper limit alarm, the alarm continues as long as the input is above or equal to the
new setting. If the input is below the new setting, the alarm turns OFF. If the alarm
type is set to delay lower limit alarm, the alarm continues as long as the input is
below or equal to the new setting. If the input is greater than the new setting, the
alarm turns OFF.
1.15 Measurement Function > Measurement Alarm Related Settings