VICI DVI User Manual

Technical Note 411

Valco Instruments Co. Inc.

Implementation of the
Digital Valve Interface (DVI)

NOTE: This technical note replaces the DVI man ual, and includes all the information except a schematic
drawing. Call Valco if a copy of the schematic is required.

The V alco Digital V alv e Interface (D VI) is an electronic controller which uses CMOS integ rated 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 posi­tions of the actuator, with the output air supplied through the one which is activ ated. 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 D VI 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 continu­ously applied to the valve. This “pulsed operation” procedure mimics valve switching by hand while
providing the advantages of powered, automated operation.

The D VI also has leads to connect a remote LED position readout, for situations in which its o wn 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 D VI f eatures a two-sided f ace/mounting plate which
is factory-installed for mounting on the left side of the instrument panel. Howe ver , 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.

1.75”

BLACK

LOAD
RELAY

1.8” 3” 4”

2”

RED

BLUE

1.35”

2.75”

Figure 1: Mounting dimensions

Figure 2: Relay connections

INJECT
RELAY

Basic Connections

1. Connect the air lines betw een the DVI and the air actuator as shown in Figure 3 on the back page.

2. Connect the air supply line to a regulated source of compressed air or nitrogen. (60-80 psi recom­mended, 100 psi maximum)

3. Connect the tr ansformer to the DVI as indicated, and plug it in.

Manual Operation

No additional installation is required for use of the three position switch on the front panel of the DVI.
The manual switch will override automatic operation unless the operation is controlled by a single
double throw relay.

Automatic Operation

The D VI can be controlled b y one doub le throw relay, two single throw relays, or remote negative true
logic. The input signals to the DVI can be continuous or as short as fifty milliseconds. Any unused
wires should be taped or tied out of the way.

One relay operation (double throw)

1. Connect the BLACK (LOAD) wire from the DVI to the Normally Closed (N.C.) relay contact.

2. Connect the RED (ground) wire to the Common (Com/Grnd) relay contact.

3. Connect the BLUE (INJECT) wire to the Normally Open (N.O.) relay contact.

Two relay operation

1. Connect the RED (ground) wire from the DVI to the common of both relays.

2. Connect the BLACK (LOAD) wire to the Normally Open (N.O.) contact of the relay designated for
the LOAD position.

3. Connect the BLUE (INJECT) wire to the Normally Open (N.O.) contact of the relay designated for
the INJECT position.