Cyclical Program With 3 Setpoints And 3 Steps; Program With Hbb (Hold Back Band) Function; Fast Simulation Of Program; Controlling The Program From The - gefran 650 Abbreviated Manual

5. Examples and applicative notes

5.13.4.4. Cyclical program with 3 setpoints and 3 steps

temperature
SP07
SP05
SP06
initial
tr5 tp5
Step 5

5.13.4.5. Program with HBB (hold back band) function

temperature
SP
T
i
tw1

5.13.5. Fast simulation of program

You can easily check a selected program by launching it
in fast simulation mode. Enable it by setting the parameter
LIMIT = On on the PR.OPT submenu.
The program will run with ramp time limited to 20 seconds
and with hold time limited to 10 seconds. If the set values
are smaller they are used. In this way the maximum dura-
tion of a step is 30 seconds.
During functioning in fast simulation, the HBB alarm is
inhibited and the control output assumes the FAULT value
on the PID submenu.
All other enabled functions (restart, start/stop, reset,
manual/automatic, end cycle or continuous cycle, event
outputs, consent from digital inputs, second channel
setpoint, etc.) are active.

5.13.6. Controlling the program from the

keypad

In the absence of enablings from digital inputs , the program
is controlled when programmer state is displayed using the
, keys, with the following modes:
• pressed with program stopped = START;
• pressed with program running = STOP;
• + pressed for 2 seconds = RESET
(condition maintained with key pressed);
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Gefran 650/1250/1350 Temperature Controller – Abbreviated Manual
tr6 tp6 tr7 tp7 tr5 tp5
Step 6 Step 7 Step 5
CICLE 1 CICLE 2
HBB
Restart program
Power
tw = waiting time
OFF
tr = ramp time
tp = permanence time
tp = tp1 + tp2
tr tp1 tw2 tp2
t t
off on
When the programmer state is not displayed, the key ( )
maintains the function selected with the parameter but1.

5.13.7. Programmer Reset mode

By setting RST.SP = ON provides that with active reset com-
mand the setpoint assumes the value of process variable PV
and power is forced to zero.
Setting RST.SP = OFF maintains the active setpoint (prior to
reset) and power control.
This function is valid in case of reset from digital inputs or
time
enabled keys, as well as in case of reset following a program
change (possible only in STOP) or STOP/START switching at
end of program.

5.13.8. Restart with step search

If configured, in case of restart the programmer can try to
restart nor from the first program step but from the point of
the program that corresponds, or is closest to, the value of
the active process variable PV.
This function mode is called "restart with step search."
At start, if Strt = RSCH was set on the PR.OPT submenu,
the program searches for the setpoint with value equal to
variable PV.
The search is conducted by shifting the current time forward
or back and skipping phases or steps.
The following diagram shows a typical 5-step program profi-
le and explains how restart with step search works
time
PV / Set point
PV1
Step 0
If the variable has values lower than the ones requested du-
ring a setpoint raise phase (point A, t1), restart is conducted
by lowering the active time base until the setpoint profile
(point A1) is intercepted.
If the variable has values lower than the ones requested
during a setpoint lower phase (point B, t2), restart is con-
ducted by raising the active time base until the setpoint
profile (point B1) is intercepted.
If interception is impossible, as in the case of variable at
value PV1, the program is restarted from the active setpoint
and time.
If the HBB control is on, programmer base times remain in
effect until the variable re-enters the set tolerance band,
symmetrical to the setpoint value.
B B1
A1 A
t1 t2
Step 1 Step 2 Step 3 Step 4
time