Fisher IM Supplement: Best Practices for use of Emerson 775 THUM WirelessHART Adapters with FIELDVUE Digital Valve Controllers Manuals & Guides

Instruction Manual

D104235X012

FIELDVUE Digital Valve Controllers

January 2021

Best Practices for use of Emerson 775 THUM

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WirelessHART® Adapters with FIELDVUE™ Digital
Valve Controllers

The Emerson Wireless 775 THUM Adapter is used to enable field devices communicating via the version 5, 6, or 7
wired HART
via a HART modem to the wired field device as well as via the WirelessHART radio to the WirelessHART network.

The THUM adapter is an external attachment to a field device and is not an integral component of it. Because of this
unique capability among WirelessHART devices and because of HART communication requirements of ValveLink
diagnostics with FIELDVUE digital valve controllers, there are “Best Practices” options related to integrating a THUM
adapter with FIELDVUE instruments that may differ from, or are in addition to, the traditional best practices for other
WirelessHART devices and networks.

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protocol to participate as members of a WirelessHART network. The THUM adapter communicates both

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Reference Documents

D DVC6200 HW2 FW7 Instruction Manual D103605X012

D DVC2000 Instruction Manual D103176X012

D DVC6200 SIS Instruction Manual D103557X012

D DVC6000 HW2 Instruction Manual D103785X012

D DVC6000 Instruction Manual (Supported) D102794X012

D DVC5000 Instruction Manual (Retired) D200442X012

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D Using OPC

D Emerson Wireless THUM Adapter Instruction Manual 00809-0100-4075

D Flyer: Emerson Wireless 775 THUM Adapter Unlock the Value in Your Existing Field Devices 00807-0200-4075

D White Paper: Smart Wireless THUM Adapter Effect on the 4-20 mA Loop

for Accessing Fisher FIELDVUE Digital Valve Controller Data D104429X012

www.Fisher.com

FIELDVUE Digital Valve Controllers

January 2021

Instruction Manual Supplement

D104235X012

Required Loop Power for THUM Adapters with FIELDVUE Instruments

In a patented design, rather than relying on battery power, a THUM adapter scavenges the electrical power it needs for
operation from the loop to which it is attached.

The configuration choice for the THUM adapter’s Voltage Drop parameter when used with FIELDVUE digital Valve
controllers should be set to “Variable Voltage Drop”.

Note

The THUM has no effect on loop current. Loop current flows through the THUM’s series loop connection (Red-Yellow Wire) thus
generating a 2 V drop. No loop current is returned through the parallel (Black-White connection). The Black/White pair are
capacitively coupled to the loop for wired HART communication purposes. Best practice is to recalibrate the Analog Input reading
of the FIELDVUE instrument while the THUM adapter is in circuit so that the FIELDVUE Instrument reads the control current at the
same level as the host commands.

The loop must be capable of supplying the power for both the THUM Adapter and the FIELDVUE Instrument sub-device
with which it is communicating.

FIELDVUE Instrument Type

Minimum required loop voltage to ensure

HART Communications (per Digital Valve

Controller Instruction Manuals)

Minimum required voltage for

powering both the FIELDVUE

Instrument and THUM Adapter

DVC6200 device type 1309
DVC6200 SIS device type 130A

10.0 VDC 12.0 VDC
DVC6000 HW2 device type 130B
DVC2000 device type 1305 9.0 VDC 11.0 VDC
DVC6000 device type 1303 11.0 VDC 13.0 VDC
DVC5000 device type 1302 12.0 VDC 14.0 VDC

Note

The minimum control current guaranteed without microprocessor restart for all FIELDVUE instruments is 3.5 mA. FIELDVUE
instruments should not be powered below this minimum control current level. The trigger point for the Low Travel Cutoff zero
pressure saturation (0.5% / 4.08 mA) is higher than the minimum control current value so there is no reason to power the
FIELDVUE instrument any lower than 3.5 mA. Doing so may risk processor restart and the loss of FIELDVUE and THUM
communications.

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Instruction Manual

D104235X012

FIELDVUE Digital Valve Controllers

January 2021

Installation Orientation

For optimum radio signal strength, the THUM Adapter should always be mounted in the vertical “THUM’s Up”
orientation with its black cap of its antenna at the highest position. As much as possible the THUM adapter should be
mounted away from metal components and structures between it and the rest of the WirelessHART antennas.

Refer to the Emerson Wireless THUM Adapter Instruction Manual, 00809-0100-4075, for more detailed specifications
for the THUM Adapter.

Installation Location

A field device communicates with a THUM Adapter as if it were an externally attached wired HART modem so the rules
of the Frequency Shift Keying (FSK) wired HART physical layer protocol apply to them. HART communication signals
exist everywhere along the control wiring to the field device so the THUM Adapter can be physically mounted
anywhere along the control wiring. The THUM Adapter is not limited to only local mounted in the terminal box of the
field device.

The recommended practice is to remote mount the THUM Adapter along the control wiring at an optimum physical
location near the Gateway to minimize the number of “hops” for wireless communication back to the Gateway. The
goal is to achieve either a “zero hop” direct line of communication or a “single hop” connection where wireless
messages are routed only through one intermediate repeater node. The WirelessHART “zero hop” or “single hop”
orientation is required to efficiently relay the numerous “request / response” HART messages involved with any
ValveLink off-line or on-line diagnostic test routine without excessive time delay or reduced communication reliability.
Any WirelessHART network with more than two hops through intermediate repeater nodes between the THUM /
FIELDVUE instrument and the Gateway could result in test execution times five to ten times longer to complete. This
must be avoided by limiting the number of message communication hops required.

4 - 20 mA Control Wiring

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FIELDVUE Digital Valve Controllers

January 2021

Instruction Manual Supplement

D104235X012

Configuration

Like any other WirelessHART device, the THUM adapter periodically replies to the Gateway via wireless burst
messaging the status of itself and the wired sub-device it is assigned to. The THUM adapter issues two HART
commands to the field device in order to obtain its status information for this broadcast. The Gateway uses this status
information as data it publishes as an OPC or Modbus
and not detailed device alert information.

HART Master Type:

Set to “Primary” if control system is non-HART communicating.
Set to “Secondary” if control system is HART-communicating.

For details on the device parameters available from FIELDVUE digital valve controllers and the THUM commands to
best retrieve them for OPC applications, see Instruction Manual Supplement Using OPC for Accessing Fisher FIELDVUE
Digital Valve Controller Data, D104429X012

.

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Server. The Gateway only serves device parameter information

Neither Emerson, Emerson Automation Solutions, nor any of their affiliated entities assumes responsibility for the selection, use or maintenance
of any product. Responsibility for proper selection, use, and maintenance of any product remains solely with the purchaser and end user.

Fisher, THUM, FIELDVUE, ValveLink are marks owned by one of the companies in the Emerson Automation Solutions business unit of Emerson Electric Co.
Emerson Automation Solutions, Emerson, and the Emerson logo are trademarks and service marks of Emerson Electric Co. HART and WirelessHART are
registered trademarks of the FieldComm Group. All other marks are the property of their respective owners.

The contents of this publication are presented for informational purposes only, and while every effort has been made to ensure their accuracy, they are not
to be construed as warranties or guarantees, express or implied, regarding the products or services described herein or their use or applicability. All sales are
governed by our terms and conditions, which are available upon request. We reserve the right to modify or improve the designs or specifications of such
products at any time without notice.

Emerson Automation Solutions

Marshalltown, Iowa 50158 USA
Sorocaba, 18087 Brazil
Cernay, 68700 France
Dubai, United Arab Emirates
Singapore 128461 Singapore

www.Fisher.com

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E 2019, 2021 Fisher Controls International LLC. All rights reserved.