Valve Off Control (Open Collector Npn Compatible); Valve Purge/Open - Aalborg SMV Operating Manual

l Direction (12Vdc CMOS compatible logic level, pin 8 on the 9-pin "D" connector)
l Speed (0-2.5 VDC analog signal, pin 4 on the 9-pin "D" connector)
When direction is LOW (GND) valve goes down (closes), when direction
is HIGH valve goes up (opens). The "speed" voltage on pin 4 determines
how quickly the valve will operate. The signal amplitude for "speed" con-
trol signal must remain within the limits of 0 to +2.5 VDC. The 2.5 Vdc
input signal corresponds to approximately 525 (±10%) steps per second.
With resolution of the stepping motor of 0.0000625"/step (in factory
default half stem mode) it results in a maximum speed about
0.0328"/sec. Valve travel distance from Home "Closed" to Home
"Opened" position is about 0.25 (+/-10%)" and it takes about 7 seconds
at speed signal equal to 2.5Vdc.
4.2 Valve OFF Control
(Open Collector NPN Compatible)
It may be necessary or desirable to set the flow and maintain that setting
while being able to turn the flow control valve off and on again. Closing
of the valve (without changing the "speed"and "direction" control signals)
can be accomplished by connecting pin 3 of the 9-pin "D" connector to
COMMON ( power ground). The Motorized valve will be given the com-
mand to close indicated by a green light on top of the unit).
Conversely, when the connection is left open or pin 3 remains unconnect-
ed the valve remains active (executes "speed"and "direction" control sig-
nals). The valve will remain active when the VALVE OFF pin remains
"floating".
This feature is compatible with open collector NPN transistor switches, as
found in DC output ports of programmable controllers and similar
devices.
The simplest means for utilizing the VALVE OFF control feature, is to con-
nect a toggle switch between the COMMON and VALVE OFF pins of the
SMV valve.
4.3 Valve Purge
At times, it may be necessary to purge the flow system with a neutraliz-
ing gas such as pure dry nitrogen. The SMV valve is capable of a full
open condition for the valve, regardless of setpoint conditions.
Connecting the PURGE pin (pin 7 on 9 pin "D" connector) to ground will
fully open the valve.
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