Viewing Device Variables And Diagnostics - Fisher FIELDVUE DVC6200 Instruction Manual

Viewing Device Variables and Diagnostics

scheduled in number of hours between tests. Any
power cycle will reset the test clock timer.
Auxiliary Terminal
The auxiliary terminal can be used for different
applications. The default configuration is for a partial
stroke test initiated by shorting the contacts wired to
the auxiliary +/− terminals of the DVC6200. Refer to
Auxiliary Terminal Wiring Length Guidelines below.
D Local Push Button
A partial stroke test command may be sent to the
digital valve controller using a set of contacts wired to
the auxiliary +/− terminals. To perform a test, the
contacts must be closed for 3 to 5 seconds and then
opened. To abort the test, close the contacts for 1
second. The last set of diagnostic data is stored in the
instrument memory for later retrieval via ValveLink
software.
D Local DI
When configured by the user interface, the Auxiliary
Terminal can be used as a discrete input from a
pressure switch, temperature switch etc., to provide an
alert.
Auxiliary Terminal Wiring Length Guidelines
The Auxiliary Input Terminals of a DVC6200 with
instrument level ODV can be used with a
locally-mounted switch for initiating a partial stroke
test. Some applications require that the partial stroke
test be initiated from a remote location.
The length for wiring connected to the Auxiliary Input
Terminals is limited by capacitance. For proper
operation of the Auxiliary Input Terminals capacitance
should not exceed 18000 pF. As with all control signal
wiring, good wiring practices should be observed to
minimize adverse effect of electrical noise on the Aux
Switch function.
Example Calculation: Capacitance per foot or per
meter is required to calculate the length of wire that
may be connected to the Aux switch input. The wire
should not exceed the capacitance limit of 18000 pF.
Typically the wire manufacturer supplies a data sheet
which provides all of the electrical properties of the
wire. The pertinent parameter is the highest possible
capacitance. If shielded wire is used, the appropriate
number is the "Conductor to Other Conductor &
Shield" value.
September 2010
Example — 18AWG Unshielded Audio, Control
and Instrumentation Cable
Manufacturer's specifications include:
Nom. Capacitance Conductor to Conductor @ 1 KHz: 26 pF/ft
Nom. Conductor DC Resistance @ 20 Deg. C: 5.96 Ohms/1000 ft
Max. Operating Voltage − UL 200 V RMS (PLTC, CMG),150 V RMS
(ITC)
Allowable Length with this cable = 18000pF /(26pF/ft) = 692 ft
Example — 18AWG Shielded Audio, Control and
Instrumentation Cable
Manufacturer's specifications include:
Nom. Characteristic Impedance: 29 Ohms
Nom. Inductance: .15 μH/ft
Nom. Capacitance Conductor to Conductor @ 1 KHz: 51 pF/ft
Nom. Cap. Cond. to other Cond. & Shield @ 1 KHz 97 pF/ft
Allowable Length with this cable = 18000pF /(97pF/ft) = 185 ft
The AUX switch input passes less than 1 mA through
the switch contacts, and uses less than 5V, therefore,
neither the resistance nor the voltage rating of the
cable are critical. Ensure that switch contact corrosion
is prevented. It is generally advisable that the switch
have gold-plated or sealed contacts.
Field Communicator
1. Connect the Field Communicator to the LOOP
terminals on the digital valve controller.
2. Turn on the Field Communicator.
3. From the Online menu, select Device Diagnostics
and Partial Stroke Test.
4. Select either Standard (10%) or Custom. With the
Custom Stroke Test, the stroke may be entered up to
30% with configurable stroking speed and pause time.
5. The currently configured Stroke, Stroking Speed,
and Pause Time is displayed. Choose "Yes" to run the
test using these values. Choose "No" to modify the
values. The default value for Stroke Speed is
0.25%/second.
6. The valve begins to move and the actual travel
reported by the digital valve controller is displayed on
the Field Communicator.
7. Once the valve has reached the endpoint, check
that the valve has reached the desired set point. The
valve should return to its original position.
For information on configuring the Partial Stroke Test,
see Partial Stroke Variables in the Detailed Setup
section.
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