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4.17.4 Delaying Setpoint Operations
The user can specify two optional delays to prolong monitoring setpoint conditions
for more time before making a decision on either setpoint operating or release. When
delay is set, the setpoint conditions should prove to be true until delay expires, i.e.
for a period at least as long as delay time, for the setpoint to be operated or released.
Both operate and release delay can be specified with 0.1 or 1 second resolution. The
maximum value allowed for delay is 9999 in either unit.
NOTES
Care must be taken when using delays with pulse triggers and interval timers.
1.
When using an interval timer as a trigger, the setpoint release delay should never be
more than the timer count interval. When a setpoint is operated, the timer
automatically runs once again. When timer expires, the timer event will be asserted
again, and the operate conditions will still be true, although a setpoint was not yet
released. In this case, the release conditions will never be realized, so that the setpoint
will be locked in the operate state permanently. To release such a setpoint, you will
need to set it up again.
2.
When you are using any pulse event as a trigger and specifies the release delay, the
pulse event can be latched once more while the release timer runs and the setpoint is
still operated. This will lock the setpoint forever because the release condition will
never be true. This may occur, for instance, when the action controlled by such a
trigger must be a one-shot action with a predefined duration, such as an energy pulse.
To prevent such a state, you should use an additional trigger condition that will
become false when the setpoint is operated. In the event of relay operation, you can
use the reversed relay status as an additional trigger.
4.17.5 Setpoint Actions
The instrument allows up to four actions to be run consequently on each setpoint
operation. The action specification includes:
• action type
• optional action target identifying the point to which the setpoint action is
intended
Table 4-5 lists available actions, the user can run on setpoint operation, and their
optional targets.
88
Operation Techniques
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