YOKOGAWA UP35A, User Manual

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11-10
IM 05P02D41-01EN
Alarm Latch Function
The alarm latch function is a function for keeping the alarm output (keeping the alarm
output on) after entering the alarm condition (alarm output is turned on) until an order to
release the alarm latch is received.
The alarm latch function has the following four types of action.
Latch 1
Cancels the alarm output when an order to release the alarm latch is received. (Alarm
output OFF.)
However, an order to release the alarm latch is ignored if the order is received during
alarm condition.
Latch 2
Always forces cancelling of the alarm output when an order to release the alarm latch
is received. (Alarm output OFF)
Latch 3
Cancels the alarm output when an order to release the alarm latch is received or when
the alarm condition is removed. (Alarm output OFF.)
Latch 4
Cancels the alarm output when an order to release the alarm latch is received. (Alarm
output OFF.)
However, cancels the alarm output for the duration of the sampling period (control
period) if an order to release the alarm latch is received during alarm condition. (Alarm
output OFF)
PV
Lit Lit
Contact type in the figure above: Energized when an event occurs (factory default).
Alarm hysteresis
Unlit Unlit
ON
ON ON
ON OFF
OFF
OFF
ON ON OFF OFF
Time
PV high limit
alarm setpoint
PV high limit
alarm indicator
PV high limit alarm output
(no latch action)
PV high limit alarm output
of latch 1 action
PV high limit alarm output
of latch 2 action
ON ON OFF OFF
PV high limit alarm output
of latch 3 action
ON ON ON
OFF during the
sampling period
OFF
PV high limit alarm output
of latch 4 action
Release order Release order
Release order Release order
Release order
Release order
Release order
Release order
11.1 Setting Alarm Type