B&B Electronics VFG3000 - Manual User Manual
Page 83
C
ONFIGURING
D
ATA
T
AGS
E
DITING
I
NTEGER
T
AGS
R
EVISION
1
P
AGE
67
T
HE
A
LARM
T
ABS
Each Alarm tab of an integer variable or formula contains the following properties...
•
The Event Mode property is used to indicate the logic that will be used to decide
whether the alarm should activate. The tables below list the available modes.
M
ODE
A
LARM WILL ACTIVATE WHEN
…
Data Match
The value of the tag is equal to the alarm’s Value.
Data Mismatch
The value of tag is not equal to the alarm’s Value.
Absolute High
The value of the tag exceeds the alarm’s Value.
Absolute Low
The value of the tag falls below the alarm’s Value.
The following modes are only available when a setpoint is defined…
M
ODE
A
LARM WILL ACTIVATE WHEN
…
Deviation High
The value of the tag exceeds the tag’s Setpoint by an
amount equal to or greater than the alarm’s Value.
Deviation Low
The value of the tag falls below the tag’s Setpoint by an
amount equal to or greater than the alarm’s Value.
Out of Band
The tag moves outside a band equal in width to twice the
alarm’s Value and centered on the tag’s Setpoint.
In Band
The tag moves inside a band equal in width to twice the
alarm’s Value and centered on the tag’s Setpoint.
•
The Value property is used to define either the absolute value at which the alarm
will be activated, or the deviation from the setpoint value. The exact
interpretation depends on the event mode as described above.
•
The Hysteresis property is used to prevent an alarm from oscillating between the
on and off states when the process is near the alarm condition. For example, for
an absolute high alarm, the alarm will become active when the tag exceeds the
alarm’s value, but will only deactivate when the tag falls below the value by an
amount greater than or equal to the alarm’s hysteresis. Remember that the