34
3-4-2 Alarm Temperatures
•
The alarm temperatures are indicated by X in the above alarm mode table. The
operation differs depending on whether the value is positive or negative.
•
Set the alarm temperature in each memory bank. The alarm temperature set-
ting is not required, however, if the alarm mode is set to 00 (no alarm function)
or 0C (HB and HS alarm).
The Standby Sequence enables delaying output of an alarm until the process
value enters the alarm range from outside the alarm range.
For example, if the alarm mode is set to Lower-limit Alarm without Standby Se-
quence, and the ambient temperature is lower than the alarm set value (i.e.,
within the alarm range), the alarm output will turn ON at startup. If, under the
same conditions, the alarm mode is set to Lower-limit Alarm with Standby Se-
quence, the alarm output will only turn ON when the process value rises once
above the alarm set value (i.e., outside the alarm range) and then drops back
below it (i.e., within the alarm range).
•
When the alarm output turns ON, the standby sequence operation will be en-
ded. The standby sequence will restart again, however, under the following
conditions.
•
If temperature control or manual operation is started.
•
If the power is turned ON.
•
If the set point is changed.
•
If the alarm temperature is changed during operation.
The following time-chart shows an example of the Lower-limit Alarm with Stand-
by Sequence Mode.
Alarm mode: Lower-limit with Standby Sequence
Process value
Standby sequence
ended
Alarm
Time
Alarm temperature
Alarm hysteresis
The alarm hysteresis is a fixed value: 1.0
°
C, 1.0
°
F
Standby Sequence
Alarm Operation Summary
Alarm Output Settings
Section 3-4
