Alarm Hysteresis; Standby Sequence; Alarm Latch - Omron E5CN User Manual

Alarm Hysteresis

Upper-limit
C
insh
Temperature
Input Shift
52.7
Value
4-2

Alarm Hysteresis

Lower-limit
C
insl
Temperature
Input Shift
-27.3
Value
4-2-1

Standby Sequence

Restart
4-2-2

Alarm Latch

Lower-limit Temperature Input Shift Value
0 − 40
× {(110 − 105) − (25 − 40)} + (25 − 40) = −27.3 (°C)
insl =
105 − 40
Upper-limit Temperature Input Shift Value
260 − 40
× {(110 − 105) − (25 − 40)} + (25 − 40) = 52.7 (°C)
insh =
105 − 40
• The hysteresis of alarm outputs when alarms are switched ON/OFF can
be set as follows:
Upper-limit alarm
ON
OFF
Alarm value
• Alarm hysteresis is set independently for each alarm in the Alarm Hyster-
esis 1 to Alarm Hysteresis 3 parameters (initial setting level).
• The default is 0.2 ( ° C/ ° F) for Controllers with Thermocouple/Resistance
Thermometer Universal Inputs and 0.02% FS for Controllers with Analog
Inputs.
• The standby sequence can be used so that an alarm will not be output
until the process value leaves the alarm range once and then enters it
again.
• For example, with a lower limit alarm, the process value will normally be
below the set point, i.e., within the alarm range, when the power supply is
turned ON, causing an alarm to be output.
If the lower limit alarm with a standby sequence is selected, an alarm will
not be output until the process value increases above the alarm set value,
i.e., until it leaves the alarm range, and then falls back below the alarm set
value.
• The standby sequence is canceled when an alarm is output. It is, how-
ever, restarted later by the Standby Sequence Reset parameter
(advanced function setting level). For details, refer to the Standby
Sequence Reset parameter in SECTION 5 Parameters.
• The alarm latch can be used to keep the alarm output ON until the latch is
canceled regardless of the temperature once the alarm output has turned
ON.
Any of the following methods can be used to clear the alarm latch.
• Turn OFF the power supply. (The alarm latch is also cleared by switching
to the initial setting level, communications setting level, advanced function
setting level, or calibration level.)
• Use the PF Key.
Lower-limit alarm
Alarm hysteresis
ON
OFF
Section 4-2
Alarm hysteresis
Alarm value
81