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Alarm Hysteresis Section 4-2
4-2 Alarm Hysteresis
• The hysteresis of alarm outputs when alarms are switched ON and OFF
can be set as follows:
• Alarm hysteresis is set independently for each alarm in the “alarm hyster-
esis 1” to “alarm hysteresis 3” parameters.
• Default is 0.2 for both ch1 and ch2.
4-2-1 Standby Sequence
• The standby sequence allows alarm outputs to be temporarily disabled
until the temperature leaves the alarm range (i.e., until an alarm condition
does not exist). Once the alarm range has been left, the alarm output will
then operate whenever the alarm range is entered.
• For example, in a standard heating application, if you use the standard
“low alarm,” the alarm output would be turned ON when the Controller is
turned ON. However, if the standby sequence is used, the alarm output is
disabled during the warmup period until the temperature goes above the
alarm SP. The alarm becomes active after the low alarm SP has been
exceeded and the output is turned ON if the temperature falls below the
alarm SP.
Restart The standby sequence is ended when an alarm is output. It is, however,
restarted (reset) later by the conditions specified in the “standby sequence
restart” parameter.
4-2-2 Alarm Latch
• The alarm latch function holds the alarm output ON once it has been
turned ON regardless of the temperature.
• The alarm latch can be canceled by turning OFF the power.
• The alarm latch can be canceled by executing operation commands using
communications. This function is supported by upgraded pulse output
models and analog output models only.
• Default is “0: OFF.”
Upper limit
alarm
Lower limit
alarm
ON
OFF
ON
OFF
Alarm hysteresis Alarm hysteresis
Alarm value Alarm value
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