Operation Techniques
85
The triggering condition specifies an event that will be recognized by the instrument
as a cause for the setpoint to be operated (activated) or released (deactivated).
Throughout this manual, an event is treated as a condition that relies on the value of
some parameter, or its status. An event is supposed to be asserted if the condition is
fulfilled, and to be released when it is not.
Setpoint actions specify the operations the user wants to run on operating the
setpoint. Setpoint actions are performed only at the time that a setpoint is operated.
When a setpoint is released, no actions are made, but if a relay output was
controlled by the setpoint, it will be also deactivated.
The optional programmable delays are typically used to prolong the event
monitoring for more time to provide reliable operation on alarm conditions.
The following sections provide a more detailed explanation of the setpoint
programming technique and setpoint operations.
4.17.3 Triggering Conditions
Each setpoint condition is specified by the five following programmable parameters:
•
conjunction operation
- a logical operation OR/AND used to combine the
current condition with other setpoint conditions
•
trigger parameter
•
operate condition
to test a trigger parameter
•
operate limit
(for a numeric trigger)
•
release limit
(for a numeric trigger)
Trigger parameter defines any measured or sensed quantity or signal that is to be
used as a trigger for setpoint operation. For the entire list of triggers, refer to
Table
B-8
. Each trigger parameter is treated as a numeric value, or logical value.
Numeric Triggers
For numeric triggers, the parameter is tested in comparison with the predefined limit
value. An operate condition can be selected from the following list:
-
greater or equal (over limit)
- less or equal (under limit)
- equal
- not equal
