Omron E5EK - MANUAL 2 User Manual page 38

+ Alarm hysteresis
' Standby
sequence
+ Close in alarm/open in alarm
' Summary of
alarm operations
The hysteresis of alarm outputs when alarms are switched ON/OFF can
be set as follows.
Upper limit alarm
Alarm hysteresis
ON
OFF
Alarm value
Alarm hysteresis is set independently for each alarm in the alarm 1 to
3 hysteresis" parameters (level 2 mode). Factory setting is 0.02:
0.02%FS".
"Standby sequence" is a function for unconditionally turning alarm out
put OFF when the process value has left the alarm range once and it next
enters the alarm range.
For example, when the alarm type is set to "deviation lower limit," gener
ally the process value is within the alarm range, and alarm output
become ON as it is as the process value when the power is turned ON is
smaller than the set point. However, if the alarm type is set to deviation
lower limit with standby sequence", alarm output first becomes ON
when the process value exceeds the alarm setting value to leave the
alarm range and once again falls below the alarm value.
When an alarm is output, the standby sequence is canceled. For details
on the standby sequence reset conditions, see Chapter 5, Expansion
Mode, Standby sequence reset method" on page 5 34.
When the controller is set to "close in alarm," the status of the alarm out
put function is output as it is. When set to "open in alarm," the status of
the alarm output function is output inverted.
Close in alarm Close in alarm
Open in alarm Open in alarm
Alarm type and close in alarm (normally open)/open in alarm (normally
close) can be set independently for each alarm.
Close in alarm/open in alarm is set in the alarm 1 to 3 open in alarm"
parameters (setup mode). Factory setting is [
The figure below visually summarizes the above description of alarm
operations (when alarm type is set to lower limit alarm (deviation) with
standby sequence"):
Alarm type: lower limit alarm (deviation)
with standby sequence
PV
Alarm value
Standby sequence
canceled
Alarm output
(close in alarm)
3.4 Setting Alarm Type
Lower limit alarm
ON
OFF
Alarm value
Output
Alarm
ON ON
OFF OFF
ON OFF
OFF ON
Alarm hysteresis
Time
Close (ON)
Open (OFF)
Alarm hysteresis
Output LED
Lit
Not lit
Lit
Not lit
] close in alarm".
3–11