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CHAPTER 4 FUNCTIONS
4
4.12 Alert Function
(2) Deviation alert
With the deviation alert, when the deviation (E) between the temperature process value (PV) and the set value
(SV) meets a particular condition, the system is put in an alert status.
The set value (SV) to be referred is either "set value (SV) monitor" or "set value (SV) setting" depending on the
alert mode. When a setting change rate limiter is specified, "set value (SV) monitor" follows the set value (SV) by
the specified change rate. (For details on the setting change rate limiter setting, refer to Page 119, Section
3.4.2 (28).)
The following table describes the use of each set value (SV) of when a setting change rate limiter is specified,
and can be referred to use a deviation alert.
(a) Set value (SV) and the setting change rate limiter setting
The following figures show the relationships of two types of set value (SV) depending on whether the setting
change rate limiter is specified or not.
• When the setting change rate limiter is not specified: The two types of set value (SV) are the same value.
Reference area of the set
value (SV)
Use (when the set value (SV) is changed)
CH Set value (SV) monitor
(Un\G25 to Un\G28)
This value is used when the temperature process value (PV) needs to follow the
changing set value (SV) within a consistent deviation (E). If the temperature process
value (PV) does not follow the set value (SV) and strays out of the set deviation range, an
alert occurs.
CH Set value (SV) setting
(Un\G34, Un\G66, Un\G98,
Un\G130)
This value is used for the alert occurrence to be determined only by the deviation (E) from
the set value (SV). In this case, how well the temperature process value (PV) is following
the changing set value (SV) does not matter. Even if the value in CH Set value (SV)
monitor (Un\G25 to Un\G28) is changing, an alert can occur depending on the deviation
(E) from the set value (SV).
0
Set value (SV) 1
Change
Temperature process value (PV)
CH Set value (SV) setting
(Un\G34, Un\G66, Un\G98, Un\G130)
and
CH Set value (SV) monitor (Un\G25 to Un\G28)
Time
Set value (SV) 2