VICI DVI - Manual

Implementation of the
Digital Valve Interface (DVI)
NOTE: This technical note replaces the DVI manual, and includes all the information except a schematic
drawing. Call Valco if a copy of the schematic is required.
The Valco Digital Valve Interface (DVI) is an electronic controller which uses CMOS integrated circuitry
to convert low power logic level signals or contact closures into pneumatic pulses for the operation of
Valco two position air actuated valves. The DVI has two solenoids which correspond to the two posi-
tions of the actuator, with the output air supplied through the one which is activated. The input signal
determining which solenoid is activated may be sent manually with the toggle switch on the front panel,
or the DVI can be connected to a data system’s timed outputs for automated valve switching.
The input signal to the DVI causes the interface circuitry to provide a two second pulse to the designated
solenoid, driving the air actuator and valve to the indicated position. Upon removal of the first signal
and application of a second, a two second pulse from the other solenoid drives the actuator to the other
position. The result is that air pressure is applied to the actuator only during switching, eliminating the
possibility of side-loading, misalignment, or other problems which can arise when torque is continu-
ously applied to the valve. This “pulsed operation” procedure mimics valve switching by hand while
providing the advantages of powered, automated operation.
The DVI also has leads to connect a remote LED position readout, for situations in which its own LEDs
are out of sight inside an instrument or in a different building. In addition, two contact closures are
provided for signalling the time of sample injections or for starting other devices, such as a gradient
programmer or data system.
Installation
The Digital Valve Interface can be easily installed by the user with the following items supplied:
1. One plug-in transformer
2. One remote 10 pin flat cable (5 feet long) for interfacing with a data system
3. 5 feet of 1/8" plastic tubing for the air supply
4. The necessary fittings for air line installation
Mounting
Mounting dimensions are shown in Figure 1. The DVI features a two-sided face/mounting plate which
is factory-installed for mounting on the left side of the instrument panel. However, its design allows the
option of removing four screws and the hex nut on the switch and re-installing the plate for mounting on
the right side.
Technical Note 411
Valco Instruments Co. Inc.