Automationdirect.com prosense PPC5 Series User Manual page 201

Alarm Latch Function
PV high limit alarm output
PV high limit alarm output
PV high limit alarm output
PV high limit alarm output
PV high limit alarm output
PPC Manual Revision 1
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 high limit
alarm setpoint
PV high limit
alarm indicator
(no latch action)
of latch 1 action
of latch 2 action
of latch 3 action
of latch 4 action
Contact type in the figure above: Energized when an event occurs (factory default).
PV
Lit Unlit
ON OFF
ON OFF
Release order
ON OFF
Release order
ON OFF
Release order
ON OFF
Release order
Chapter 9: Alarm Functions
Alarm hysteresis
Lit
ON
ON
Release order
ON OFF
Release order
ON OFF
Release order
ON ON
OFF during the
Release order
sampling period
Unlit
OFF
Time
9-11