Timer Operation; Dwell Timer; Simple Programmer; Delayed Switch On Timer - Eurotherm 3216 User Manual

7.

TIMER OPERATION

A timer can be configured to operate in three different modes. These can be
selected in Level 2.
1.

Dwell timer

2.

Delayed switch on timer

3.

Soft start timer

There are four operating states, all of which are available in Level 1:
Run may be initiated by pressing and together.
Reset (of End State) when timer has timed out, may be initiated by pressing
and (Ack),
Reset, during timing, may be initiated by pressing and holding
(Note pressing Ack at this point does not reset the timer. The reason for this
is that if the display is on any view other than the HOME display then
pressing these two buttons will jump to HOME).
Hold may be initiated by pressing and
hold, press quickly and again
The above states may also be set by the following methods:-
•
Edge trigger a suitably configured digital input
•
Power cycle the controller
•
Digital communications command
End cannot be set - it occurs automatically when the timer has counted
down to zero
Switching from Hold to Run through the front panel buttons is not allowable
if the Hold status is forced by a logic input or through Digital
Communications.
Timer operation is indicated by a beacon labelled RUN:
Timer Status RUN beacon
Reset Off
Run On
Hold Flashing
End Off
Logic outputs The timer may be configured to operate an output when it is
running or during the end state
Note:-
•
Power up - the 'run' state is selected if a Soft Start or Delay
timer is configured or the 'Reset' state is selected if a Dwell timer
is configured.
•
Auto/Manual is only available when the timer is in Reset
•
Ramp Rate – it is recommended that ramp rate is used only with
a Dwell type timer
•
Quick access to the timer operating parameters is available in
Level 2 by pressing . Repeat pressing of this button shows
Timer Status, Dwell, Working Output, SP1, SP2, etc
7.1. Dwell Timer
A dwell timer (TI.CFG = DWELL) is used to control a process at a fixed
temperature for a defined period. The action which occurs at the end of the
timed period depends on the configuration of the END.T parameter.
Temp
SP1
Scrolling
and
OFF
message
RESET
Digital Input
RUN Digital O/P = t.run
To run the timer from
END Digital O/P = t.End
Notes:
1. If THRES = 2
the RUN beacon on but will not start counting down until the
temperature is, first, within 2
2. The DWELL period can be reduced or increased when the timer is
running. If it is reduced to meet the Time Elapsed the timer will
change to the End state.
3. A-M can only be selected when in reset
4. If the timer is re-configured to a different type or the End Type is re-
configured (a dwell, for example), it may be necessary to reselect Auto
mode
7.1.1.

Simple Programmer

A four segment programmer is achieved using a dwell type timer with the set
point rate limit and threshold parameters set.
Temp
SP1
o
(70 C)
Servo
to PV
start
SP2
o
(20 C)
Scrolling
message
RESET
Digital
input
RUN Digital O/P = t.run
END Digital O/P = t.End
7.2. Delayed Switch On timer
The timer is used to switch on the output power after a set time.
When the timer status = run, the control output is off
End State e n d . t =
OFF SP2
THRES
= + n
Counting
SP2
down
TIMER END
OFF
TIMER RUNNING
OFF
o
(for example) timer will show TIMER RUNNING with
o
of SP. Then the threshold is ignored.
DWELL
Ramp to Ramp to
SP1 at
SP2 at
SP.RAT
SP.RAT
Counting down
TIMER
TIMER RUNNING
END
When the timer status = reset, the control output is controlling at SP1
Temperature
SP1 (70)
dwel
Scrolling
TIMER RUNNING TIMER END
Message
Run
Time
RESET
Digital
input
RUN Digital O/P = t.run
END Digital O/P = t.End
7.3. Soft Start Timer
The timer is used to start a process at reduced power and/or reduced
setpoint. Timing starts at power up or when 'Run' is selected.
When the Timer Status = Run, the controller power is limited by the soft
start power limit parameter. The Soft Start setpoint is a threshold which,
when exceeded, sets the timer to end. If the temperature is already above
this threshold when the timer is set to run, the timer will time out
immediately.
When the timer status = reset, the controller is controlling at SP1
Temp
o
Setpoint (70 C)
Soft start setpoint
o
THRES
S S . S P (50 C)
= +n
Output power High limit
Timer soft start power limit
S S . P W R (40%)
Time
Scrolling TIMER
Message RUNNING
Run
RESET
Digital input
RUN Digital O/P = t.run
END Digital O/P = t.End
Time
Reset
Time
Time
TIMER
END
Reset