6 • VALVE CONTROL MODES
With the controller in manual, the setting of parameter At.ty
≥
8
allows direct control of the valve open and close commands;
the instrument indicates the presumed or real position (for type
V2):
V0 - for floating valve without potentiometer;
V2 - for valve with feedback from potentiometer.
Model V0 have similar behaviour: every manoeuvre request
greater than the minimum impulse t_Lo is sent to the actuator
by means of the OPEN/CLOSE relays; every action updates
the presumed position of the virtual potentiometer calculated
on the basis of the actuator travel declared time.
In this way there is always a presumed position of the valve
which is compared with the position request of the controller.
Having reached a presumed extreme position (entirely open or
entirely closed determined by the “virtual potentiometer”) the
controller provides a command in the same direction, in this
way ensuring the real extreme position is reached (minimum
command time = t.on).
The actuators are usually protected against the OPEN
command in the entirely open position or CLOSE command in
the entirely closed position.
The V2 model reads the real position of the valve by means of
the auxiliary analogue input, expresses the value as a
percentage (0.0 – 100.0%) and compares it with the position
requested by the controller, then sends the appropriate
command to the valve.
The auxiliary input of the controller is used to obtain the valve
position.
Calibration is requested to memorise the extreme position of
the potentiometer, minimum and maximum.
The potentiometer is usually supplied by the controller itself
V3 - for floating valve, PI control
When the difference between the position calculated by the
controller and the only proportional component exceeds the
value corresponding to the minimum impulse t_Lo the
controller provides an OPEN or CLOSE command of the
duration of the minimum impulse itself t_Lo.
At each delivery the integral component of the command is set
to zero (discharge of the integral).
The frequency and duration of the impulses is correlated to the
integral time (_ti_).
Non-movement behavior
t_Hi = 0: with power = 100% or 0.0%, the corresponding open
or close outputs always remain enabled (safety status).
Movement behavior
t_Hi < > 0: with position attained corresponding to 100% or
0.0%, the corresponding open or close outputs are switched
off.
t_Hi
t.on
t.on
t.on
t.off
t.off
t.off
If t.off = 0, current function is
maintained.
If t.off ¤ 0 movement mode
will be as shown on the graph
7 • AUTOMATIC CALIBRATION OF CONNECTED POTENTIOMETER
1) Enable virtual keyboard
[191] Hd.1 = 2
[224] S.In = bit 5 = 1
[345] Status6_W = bit 7 = 1
2) Minimum value
[311] Page = 31
[312] Row = 0
Minimum procedure
Set the potentiometer in minimum position by activating the
close output (OUT 7), setting bit 1 = 1 di [320] NEW TAST.
When the position is reached, reset bit 1 = 0 of [320] NEW
TAST.
Confirm the minimum calibration by setting bit 0 = 1 of [320]
NEW TAST and resetting within 0.5 sec.
Maximum procedure
Set the potentiometer in maximum position by activating the
open output (OUT 1), setting bit 3 = 1 of [320] NEW TAST.
When the position is reached, reset bit 3 = 0 of [320] NEW
TAST.
Confirm the maximum calibration by setting bit 0 = 1 of [320]
NEW TAST and resetting within 0.5 sec.
8 • MANUAL CALIBRATION OF VALVE
Enable virtual keyboard
[191] Hd.1 = 2
[224] S.In = bit 5 = 1
[345] Status6_W = bit 7
Set bit 1 = 1 of [320] NEW TAST to command the close
output (OUT 7).
Set bit 3 = 1 of [320] NEW TAST to command the open output
(OUT 1).
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80346B_MHW_GFX-VALVOLE_0709_ENG