Precision Digital Corporation PD6908 User manual

PD6908 Ex-Proof & I.S. Loop-Powered Process Meter
Instruction Manual
PRECISION DIGITAL CORPORATION
233 South Street • Hopkinton MA 01748 USA
Tel [phone] • Fax [phone]
www.predig.com
•Fully-Approved Explosion-Proof & Intrinsically Safe Loop-Powered Process Meters
•4-20 mA Input Displayed with ±0.02% of Full-Scale Accuracy
•1.5 Volt Drop (4.7 Volt Drop with Backlight)
•0.7" (17.0 mm) 5 Alphanumeric Characters Top Display
•0.4" (10.2 mm) 8 Alphanumeric Characters Bottom Display
•20-Segment Bargraph Standard
•Display Mountable at 0°, 90°, 180°, & 270°
•CapTouch Through-Glass Button Programming with Normal and Delayed Modes
•Loop-Powered Backlight with Red Backlight for Alarm Conditions
•(2) Open Collector Outputs Standard; Assignable toPulse, Alarm, Timer, or Stopwatch
•(2) Optional Loop-Powered Solid-State Relays; Assignable to Alarm, Control, Timer, or Stopwatch
•Stopwatch & Timer Functions to Drive Relays & Open Collectors
•Optional Isolated 4-20 mA Analog Output
•Relay Pump Alternation Based on Level and Runtime
•Display Relay Runtime & Cycle Count via Relay Info Menu
•Round Horizontal Tank Function; Just Enter Diameter & Length
•32-Point Linearization, Square Root Extraction andProgrammableExponent Function
•Free PC-Based MeterView XL USB Programming Software
•HART®Protocol Transparent
•Enable and Disable Backlight from Menu
•Operating Temperature Range: -40 to 75°C (-40 to 167°F)
•Installation Temperature Range: -55 to 75°C (-67 to 167°F)
•Conformal Coated PCBs for Dust & Humidity Protection
•Password Protection
•CSA Certified for Explosion-Proof / Dust-Ignition Proof / Flame-Proof
•ATEX and IECEx Certified as Intrinsically Safe and Explosion-Proof
•Flange for Wall or Pipe Mounting; Loop for Stainless Steel Tag; Holes for Tamper-Proof Seal
•Explosion-Proof, IP68, NEMA 4X Die-Cast Aluminum & Stainless Steel Enclosures
•3-Year Warranty
IECEx
MeterView XL
USB Install

PD6908 Explosion-Proof & Intrinsically Safe Loop-Powered Process Meter
Instruction Manual
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The Complete PD6900 Series
Plastic Enclosures - General Purpose
PD6907-GP-PL
4-20 mA Input
Feet & Inches Meter
PD6908-GP-PL
4-20 mA Input
Process Meter
PD6928-GP-PL
4-20 mA Input
Flow Rate/Totalizer
PD6938-GP-PL
Pulse Input
Flow Rate/Totalizer
Aluminum Enclosures - Hazardous Area Approved
PD6907-HA-AL
4-20 mA Input
Feet & Inches Meter
PD6908-HA-AL
4-20 mA Input
Process Meter
PD6928-HA-AL
4-20 mA Input
Flow Rate/Totalizer
PD6938-XX-AL
Pulse Input
Flow Rate/Totalizer
Stainless Steel Enclosures - Hazardous Area Approved
PD6907-HA-SS
4-20 mA Input
Feet & Inches Meter
PD6908-HA-SS
4-20 mA Input
Process Meter
PD6928-HA-SS
4-20 mA Input
Flow Rate/Totalizer
PD6938-XX-SS
Pulse Input
Flow Rate/Totalizer

PD6908 Explosion-Proof & Intrinsically Safe Loop-Powered Process Meter
Instruction Manual
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Table of Contents
Introduction..........................................................................................................6
Key Features ........................................................................................................7
Ordering Information.........................................................................................11
Accessories ...................................................................................................11
Specifications.....................................................................................................13
Display............................................................................................................13
General...........................................................................................................13
Enclosure.......................................................................................................14
Input................................................................................................................14
Common Open Collector & Relay Specifications.......................................15
Open Collector Outputs................................................................................15
Solid-State Relays .........................................................................................15
4-20 mA Transmitter Output.........................................................................15
On-Board Digital Input..................................................................................15
MeterView XL Software.................................................................................16
Compliance Information....................................................................................17
Electromagnetic Compatibility.....................................................................17
Hazardous Area Approvals...........................................................................17
EU Declaration of Conformity...........................................................................18
Safety Information .............................................................................................18
Installation..........................................................................................................18
Unpacking......................................................................................................18
Mounting.............................................................................................................19
Dimensions....................................................................................................19
Cover Jam Screw...........................................................................................19
Connections.......................................................................................................20
Display & Options Modules..........................................................................20
Connectors Labeling.....................................................................................21
Wiring Diagrams ................................................................................................23
Intrinsically Safe Wiring................................................................................23
I/O Parameter Table....................................................................................23
Explosion-Proof Wiring.................................................................................23
Current Loop (4-20 mA) Connections .........................................................23
Digital Input Connections ............................................................................24
4-20 mA Output Connections......................................................................24
Solid-State Relay Connections....................................................................24
Open Collector Output Connections............................................................24
Setup and Programming...................................................................................25
Overview.........................................................................................................25
CapTouch Buttons ........................................................................................25
CapTouch Buttons Delay ............................................................................25
Turning Off CapTouch Buttons....................................................................25
CapTouch Button Tips & Troubleshooting ..................................................25
MeterView XL Programming Software.........................................................26
CapTouch Buttons and Status Indicators...................................................27
Display Functions & Messages....................................................................28
Main Menu......................................................................................................32
Setting Numeric Values...............................................................................33
Scalingthe4-20mAInput(INPUT)...................................................................34
Available Unit Classes and Units ................................................................35
Setting Custom Units (CUSTOM)..................................................................36
Setting the Display Features (DISPLAY).....................................................36
Changing the Engineering Units (UNITS)...................................................36
Changing the Decimal Point (DEC.PT).........................................................36
Enabling or Disabling Commas on the Bottom Display (COMMA)................37
Display Capabilities Optimization (TOP and BOTTOM) ................................37
Configuring the Display (TOp and BOTTOM)................................................38
Programming the Bargraph (BARGRAPH)....................................................39

PD6908 Explosion-Proof & Intrinsically Safe Loop-Powered Process Meter
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Programming the Outputs (OUTPUT)...........................................................39
Open Collector Outputs ( OPEN COLLECTR ) .................................................40
Solid-State Relay Outputs (RELAY) ............................................................45
Isolated 4-20 mA Output (4-20 mA) ..........................................................51
Output Manual Control (CONTROL).............................................................51
Advanced Features Menu (ADVANCE)..........................................................52
Advanced Process Variable Setup (ADV PV SETUP) ...............................53
Low-Flow Cutoff (CUTOFF)..........................................................................60
Noise Filter (FILTER) .................................................................................60
Enabling Password Protection (PASSWRD) .................................................60
Programmable Function Keys User Menu (USER)......................................61
Tare (TARE).................................................................................................62
Changing System Settings (SYSTEM).........................................................63
Meter Operation .................................................................................................65
CapTouch Buttons Operation ......................................................................65
CapTouch Buttons ........................................................................................65
CapTouch Button Tips & Troubleshooting ..................................................65
Function Keys Operation..............................................................................66
Digital Input Operation..................................................................................66
Maximum/Minimum Readings......................................................................66
Runtime & Cycle Count (INFO)....................................................................66
Changing Engineering Units........................................................................66
Troubleshooting.................................................................................................67
Reset Meter to Factory Defaults...................................................................67
Determining Software Version.....................................................................67
Factory Default Settings..............................................................................68
Troubleshooting Tips....................................................................................69

PD6908 Explosion-Proof & Intrinsically Safe Loop-Powered Process Meter
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Table of Figures
Figure 1. Enclosure Dimensions –Front View....................................................19
Figure 2. Enclosure Dimensions –Side View .....................................................19
Figure 3. Enclosure Dimensions –Top View ......................................................19
Figure 4. Connector Labeling for PD6908-HA-##-LNN.......................................21
Figure 5. Connector Labeling for PD6908-HA-##-L2N........................................21
Figure 6. Connector Labeling for PD6908-HA-##-L3N........................................22
Figure 7. Connector Labeling for PD6908-HA-##-L5N........................................22
Figure 8. 4-20 mA Input Connection without Backlight .....................................23
Figure 9. 4-20 mA Input Connection with Backlight...........................................23
Figure 10. Digital Input Connections ...................................................................24
Figure 11. 4-20 mA Output Connections .............................................................24
Figure 12. Solid-State Relay Connections...........................................................24
Figure 13. Open Collector Output Connections..................................................24
Video
Watch the Loop-Powered Meters Video
Click or Scan

PD6908 Explosion-Proof & Intrinsically Safe Loop-Powered Process Meter
Instruction Manual
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Disclaimer
The information contained in this document is
subject to change without notice. Precision Digital
Corporation makes no representations or
warranties with respect to the contents hereof;
and specifically disclaims any implied warranties
of merchantability or fitness for a particular
purpose.
•Read complete instructions prior to installation
and operation of the meter.
•This product is not recommended for life support
applications or applications where malfunctioning
could result in personal injury or property loss.
Anyone using this product for such applications
does so at his/her own risk. Precision Digital
Corporation shall not be held liable for damages
resulting from such improper use.
•Failure to follow installation guidelines could
result in death or serious injury. Make sure only
qualified personnel perform the installation.
•For Explosion-Proof / Dust-Ignition Proof / Flame-
Proof applications, never remove the meter cover
in explosive environments when the circuit is live.
•Cover must be fully engaged to meet for
Explosion-Proof / Dust-Ignition Proof / Flame-
Proof requirements.
WARNING
Cancer and Reproductive Harm - www.P65Warnings.ca.gov
Limited Warranty
Precision Digital Corporation warrants this
product against defects in material or
workmanship for the specified period under
“Specifications” from the date of shipment from
the factory. Precision Digital’s liability under this
limited warranty shall not exceed the purchase
value, repair, or replacement of the defective unit.
See Warranty Information and Terms &
Conditions on www.predig.com for complete
details.
Registered Trademarks
All trademarks mentioned in this document are
the property of their respective owners.
© 2023 Precision Digital Corporation.
All rights reserved.
Introduction
The PD6908 ProtEX+ loop-powered explosion-proof
& intrinsically safe meters can be installed virtually
anywhere to provide convenient and informative
display of any 4-20 mA signal. They can operate
down to -40°C and be installed in areas that get as
cold as -55°C, however the display will cease
functioning. One of the most convenient features of
these instruments is their dual-line display which is
typically used to display the process variable on the
5-character alphanumeric top display and the units of
measure or a tag on the 8-character alphanumeric
bottom display. Another common setup is to display
the input in one scale on the top display (such as feet)
and in another scale on the bottom display (such as
gallons). The top display uses 12-segment, and the
bottom display uses 14-segment alphanumeric
characters for clear indication of tags, units, or alarm
messages.
Further enhancing the display on these instruments is
a 20-segment bargraph.
These loop-powered meters can be installed virtually
anywhere because they get their power from the
4-20 mA loop and therefore require no separate
power source. And they only drop 1.5 V (4.7 V with
backlight), so they add very little burden to the loop.
Additional features that allow these instruments to be
installed virtually anywhere include a NEMA 4X, IP68
explosion-proof enclosure, an operating temperature
range of -40 to 167°F (-40 to 75°C), conformally
coated PCBs, and a backlit LCD that can be read in
bright sunlight or dimly lit areas.
The ProtEX+ Series is CSA Certified as Explosion-
Proof / Dust-Ignition Proof / Flame-Proof and ATEX
and IECEx Certified as Intrinsically Safe and
Explosion-Proof. The enclosure itself is ATEX, IECEx,
CSA, and UL approved.
Free, PC-based, MeterView XL software that
connects to the meter via a micro USB cable is
available for programming and setup of the meters.
For more details, see the MeterView XL manual. Four
CapTouch through-glass buttons are available to
operate the instrument without removing the cover.
All models come equipped with two open collector
outputs and a digital input. There are also models
available with two solid-state relays and isolated
4-20 mA analog output options. The open collector
outputs are useful for alarm indication. The digital
input can be used to acknowledge the relays, to
start/stop a timer/stopwatch, and more. The relays
can be programmed for alarm indication, on/off
control, or pump alternation.

PD6908 Explosion-Proof & Intrinsically Safe Loop-Powered Process Meter
Instruction Manual
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Key Features
2X More Informative Display
The PD6908 display offers a 50% larger display area
and is twice more informative than previous
generations of loop-powered explosion-proof meters.
Featuring an alphanumeric dual-line display and a
20-segment bargraph, reading and understanding
process values is easy and intuitive. The addition of
status indicators provides a quick glance at alarm
conditions, relays, process trends, and more.
Predefined display units give users even more display
flexibility. Plus, the high contrast backlit LCD display
is readable from far away and under various lighting
conditions.
Backlight Turns Red on Alarm
When an alarm occurs, the display can be
programmed to turn red, flash, and display an alarm
indicator . In addition, a unique custom alarm
message for each of the two relays and two open
collectors can be displayed on the bottom display.
These features can be activated even if no relay or
open collector is connected.
CapTouch Through-Glass
Buttons
The PD6908 is equipped with four capacitive sensors
that operate as through-glass buttons so that it can be
operated without removing the cover (and exposing
the electronics) in a hazardous area. CapTouch
buttons are designed to work under any lighting
condition and to protect against false triggering. They
can be disabled for security via a switch on the
display module.
CapTouch buttons have two modes of operation:
Normal and Delayed. Delayed mode prevents
accidental trigger of the buttons. In the Delayed
mode, the buttons enter into a low sensitivity state
(sleep) and they ignore quick button presses after 20
seconds of inactivity. To wake up the buttons, press
and hold any button for more than 2 seconds, the
buttons respond normally.
Solid State Relays 1-2
Indicators
Predefined
Display Units
0.7" (17.0 mm) High
5-Character, Alphanumeric
12-segment
Password Protection
Process Trend
Indicators
CapTouch Buttons
Self-Calibration
0.4" (10.2 mm) High
8-Character, Alphanumeric
14-segment
Two-Color
Backlight
Alarm Indicator
20-Segment
Bargraph
CapTouch Buttons /
Function Keys

PD6908 Explosion-Proof & Intrinsically Safe Loop-Powered Process Meter
Instruction Manual
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Wide Viewing Angle
The window and display module have been optimized
to provide a wide viewing angle of approximately
±40°; nearly twice that of the competition. Plus, the
display module can be rotated in 90° increments
providing added mounting flexibility.
Dual-Scale Feature
Users can use the dual-scale feature to display the
input in two different scales. For instance, the
example above shows an application where the
display shows the input in feet and gallons while the
display toggles between process values and units.
Predefined and Custom Units
The meter has six available preprogrammed unit
classes: volume, height, temperature, pressure,
weight, and rate. When the desired unit class or unit
of measure within a class is not available, a custom
unit may be programmed.
14-Segment Characters
Notice how much better letters like “T”, “N” and “K”
appear as 14-segment characters on the bottom display
vs. 7-segment characters found on other meters.
Password Protection
A password can be set up for programming security to
prevent unauthorized changes to the programmed
parameter settings.
Enable / Disable Backlight
The backlight may be enabled or disabled using the
System - Backlight menu. The backlight is enabled by
default, but the input must be wired appropriately for
the backlight to function. See Enabling or Disabling
the Backlight (BACKLITE) on page 64 for details.
Multiple Outputs
•Two open collector outputs (standard)
•Two solid-state relays (optional)
•One 4-20 mA output (optional)
The open collector outputs and relays generally
operate in the same manner, with the major exception
being the open collectors are not available for pump
alternation and the relays are not available with pulse
features. The open collectors and relays can be
controlled either automatically or manually.
The isolated analog output signal can be configured
to represent the process variable (PV1, PV2, or
retransmit). It can also be reverse scaled such that
the meter’s high calibration value outputs 4 mA and
the meter’s low calibration outputs 20 mA.
Free MeterView XL
Programming Software
The fastest and easiest way to program the meter is
using the free Meterview XL programming software.
This software greatly simplifies the programming
process and allows the user to save configuration files
for later use.
The meter connects to the PC via a provided micro-
USB cable and is powered by the USB connection, so
no additional power is needed during programming.
Easy Wiring & Service
The PD6908 has been designed for easy wiring and
servicing. All connections are made to removable
screw terminal blocks. There are no exposed printed
circuit boards.

PD6908 Explosion-Proof & Intrinsically Safe Loop-Powered Process Meter
Instruction Manual
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Modern and Practical Enclosure
The PD6908 NEMA 4X, IP68 enclosure provides
serious protection from the elements, high impact,
corrosion, and electrical interference. Plus, the
extensive worldwide agency approvals allow it to be
installed virtually anywhere.
Aluminum or Stainless Steel Enclosure
The enclosure is available in copper-free (0.3%),
die-cast aluminum and type 316 stainless steel.
Built-In Flange for Pipe Mounting
The built-in mounting flange allows easy mounting to
walls or pipes.
A slot on the back makes it easy to center the unit on
a pipe. There are two ¾" NPT threaded conduit holes
for wiring.
Grounding Screw
A grounding screw is provided on the top of the
enclosure.
SS Tag Attaching Loop
The enclosure is also equipped with a loop at the top
to easily attach a PDA-SSTAG stainless steel tag.
Tamper-Proof Capability
The instrument can be made tamper-proof by
inserting a wire through the built-in loop on the base
of the enclosure and a hole in the lid of the enclosure
and securing this wire with a lead seal.

PD6908 Explosion-Proof & Intrinsically Safe Loop-Powered Process Meter
Instruction Manual
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Pump Alternation
The PD6908 can be used as a pump controller to
alternate two pumps and indicate high and low alarm
conditions. The pumps can be programmed to
alternate on level and runtime and the display can be
programmed to turn red and flash a message on
alarm conditions. The meter can display the pump
runtimes and the number of times they have cycled.
See the Pump Control with Alternation & Alarm
Example on page 49 for full details.
Relay #2 turns the main pump on at 6000 gallons and
turns it off at 1000 gallons. lights up to show relay
2 is energized. The indicates level is rising.
With the Pump Alternation feature activated, the next
time the level reaches 6000 gallons, relay #1 transfers
and starts the backup pump. lights up to show
relay 1 is on.
Input Signal Conditioning
To satisfy applications that require scaling in ways
other than the usual 2-point linear method, the
PD6908 can also be scaled for square root (DP flow),
programmable exponent (open channel flow) or round
horizontal tank volume calculation.
Round Horizontal Tank
Linearization
This function automatically calculates the volume in a
round horizontal tank with flat ends and allows that
reading to be displayed on the bottom display. This
results in a meter that displays the height of the tank
on the top display and volume on the lower display.
The user only needs to enter the diameter and length
of the tank and the meter takes care of the rest.
Square Root Linearization
The square root function can be used to linearize the
signal from a differential pressure transmitter and
display flow rate in engineering units.
Programmable Exponent
Linearization
The programmable exponent can be used to linearize
the signal from level transmitters in open-channel flow
applications using weirs and flumes.

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Ordering Information
Hazardous Area Instruments
ProtEX+ PD6908 • Decimal Models –Aluminum Enclosure
Model
Description
PD6908-HA-AL-LNN
Loop-Powered Explosion-Proof & Intrinsically Safe Process Meter, No Options
PD6908-HA-AL-L2N
Loop-Powered Explosion-Proof & Intrinsically Safe Process Meter, Two Solid-State Relays
PD6908-HA-AL-L3N
Loop-Powered Explosion-Proof & Intrinsically Safe Process Meter, 4-20 mA Analog Output
PD6908-HA-AL-L5N
Loop-Powered Explosion-Proof & Intrinsically Safe Process Meter, Two Solid-State Relays
& 4-20 mA Analog Output
ProtEX+ PD6908 • Decimal Models –Stainless Steel Enclosure
Model
Description
PD6908-HA-SS-LNN
Loop-Powered Explosion-Proof & Intrinsically Safe Process Meter, No Options
PD6908-HA-SS-L2N
Loop-Powered Explosion-Proof & Intrinsically Safe Process Meter, Two Solid-State Relays
PD6908-HA-SS-L3N
Loop-Powered Explosion-Proof & Intrinsically Safe Process Meter, 4-20 mA Analog Output
PD6908-HA-SS-L5N
Loop-Powered Explosion-Proof & Intrinsically Safe Process Meter, Two Solid-State Relays
& 4-20 mA Analog Output
Notes:
1. All models come with bargraph, two open collector outputs, and one digital input standard.
2. The meter comes standard with two ¾" NPT conduit holes. To order models with M20 conduit holes instead, add -21 at the end
of the part number (e.g. PD6908-HA-AL-LNN-21)
Accessories
Model
Description
PD659
Signal Isolators, Splitters, and Conditioners
PD9501
Multi-Function Calibrator
PD9502
Low-Cost Signal Generator
PDA1002
6" DIN Rail Mounting Kit
PDA1024-01
24 VDC Transmitter Power Supply for DIN Rail
PDA6846
Steel 2" U-Bolt Kit. All Material: Zinc Plated Steel; (1) U-Bolt for 2" Pipe with (2) Washers,
(2) Lock Washers, and (2) Nuts
PDA6846-SS
Stainless Steel 2" U-Bolt Kit. All Material: Stainless Steel; (1) U-Bolt for 2" Pipe with (2) Washers,
(2) Lock Washers, and (2) Nuts
PDAPLUG75
3/4" NPT 316 Stainless Steel Conduit Plug with Approvals
PDAREDUCER-75M-
50F
M-3/4" NPT to F-1/2" NPT Reducer with Approvals
PDAREDUCER-75M-
M20F
M-3/4" NPT to F-M20 Reducer with Approvals
PDA-SSTAG
Custom Stainless Steel Tag (see website for convenient ordering form)
•Accessories do not carry hazardous area approvals unless otherwise specified and are thus not suitable for
location in hazardous areas. The use of additional protective devices may allow them to be installed in a safe
area and connected to a device in a hazardous area. User should consult a professional engineer to determine
suitability of these products for their specific application.

PD6908 Explosion-Proof & Intrinsically Safe Loop-Powered Process Meter
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PDA1024-01 24 VDC Power Supply
The PDA1024-01 is a DIN rail mounted 1.5 A,
24 VDC power supply that can be used to power
the 4-20 mA transmitter.
PDA6846 2"U-Bolt Kits
The PDA6846 U-Bolt Kits provide a convenient way to
mount the meter to 1.5" or 2" pipes. They are
available in steel and stainless steel.
PDA-SSTAG Stainless Steel Tag
The PDA-SSTAG is a laser etched stainless steel tag
that can be customized with three lines of text.
Each tag comes with a stainless steel wire and lead
seal for easy mounting wherever you need.
PD9501 Multi-Function Calibrator
This PD9501 Multi-Function Calibrator has a variety
of signal measurement and output functions, including
voltage, current, thermocouple, and RTD.
PD9502 Low-Cost Signal Generator
The PD9502 is a low-cost, compact, simple to use
4-20 mA or 0-10 VDC signal generator. It can easily
be set for 0-20 mA, 4-20 mA, 0-10 V or 2-10 V
ranges. Signal adjustment is made with a one-turn
knob. A wall plug is provided with the instrument.
Optional USB power bank is available.

PD6908 Explosion-Proof & Intrinsically Safe Loop-Powered Process Meter
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Specifications
Except where noted all specifications apply to operation at +25°C.
Display
Display
Dual-line LCD with backlight.
Both lines: alphanumeric
Top: 0.7" (17.8 mm) 5 digits, 12-segment
Bottom: 0.4" (10.2 mm) 8 characters,
14-segment
Display may be programmed to turn red and
flash a user-defined message on
alarm condition.
On-Screen
Indicators
See CapTouch Buttons and Status Indicators
on page 27 for details.
Top Display
5 digits (-9999 to 99999) or 5 characters
Bottom
Display
8 digits (-9,999,999 to 99,999,999; separated
by commas) or 8 characters
(all capital & most lower-case letters)
Backlight
Powered by 4-20 mA loop
Intensity varies with signal level
Bargraph
20 segments
Decimal Point
Up to four decimal places on top display and
up to seven decimal places on bottom display
Commas
Commas to indicate 1000s
(e.g. 88,987,628) on the bottom display only
Dual-Scale
Feature
The input can be displayed in different scales
on the top and bottom displays. For instance,
the top display could display the input in
height units and the bottom display could
show that same input in volume units.
Alarm
Indication
Programmable: loop-powered red backlight,
flashing display, alarm symbol , bargraph
segment flashes on alarm.
Custom
Alarm
Messages
Programmableforeachrelay/opencollector:
8charactersmaximum;displayed every10secfor
1seconbottomdisplay.Maybe turnedoff.
Display
Update Rate
Ambient > -10°C: 1 Update/Second
Ambient = -20°C: 1 Update/2 Seconds
From -20°C to -40°C the update rate slows
down 1 second for every -2°C
(e.g. at -24°C, 1 update/4 seconds).
Overrange
Top: 99999; Bottom: 99,999,999 (flashing)
Underrange
Top: -9999; Bottom: -9,999,999 (flashing)
General
Programming
Method
Four CapTouch through-glass buttons when
cover is installed. The CapTouch buttons can
be used with the cover removed.
Free PC-based USB MeterView XL
programming software.
Environmental
Operating temperature range:
-40 to 75°C (-40 to 167°F)
Storage temperature range:
-55 to 85°C (-67 to 185°F)
Installation temperature range:
-55 to 75°C (-67 to 167°F)
(The display ceases to function, however
inputs and outputs continue to operate)
Relative humidity: 0 to 90% non-condensing
Printed circuit boards are conformally coated
Noise Filter
Averages the input signal over a period of
time between 1 and 16 seconds to dampen
the effects of a noisy signal that causes a
jumpy display.
Filter Bypass
0.0 to 99.9% of full scale. Input signal
changes that are greater than the bypass
value are displayed immediately.
Recalibration
Recalibration is recommended at least every
12 months.
Max / Min
Display
Max / min readings reached by the process
are stored until reset by the user or until
power to the meter is turned off.
Tare
Tare function zeros out the meter to remove
the weight of a container.
Tare function can be assigned to a function
key or the digital input.
Password
Programmable password restricts
modification of programmed settings.
Non-Volatile
Memory
All programmed settings are stored in non-
volatile memory for a minimum of ten years if
power is lost.
Normal Mode
Rejection
64 dB at 50/60 Hz
Connections
Removable screw terminal blocks
Display terminals: accept 16 to 30 AWG wire
Relay terminals: accept 12 to 26 AWG wire
4-20 mA output: accept 16 to 30 AWG wire
Tightening
Torque
Display terminals: 2.5 lb-in (0.28 Nm)
Relay terminals: 4.5 lb-in (0.5 Nm)
4-20 mA output terminals: 2.5 lb-in (0.28 Nm)
Overall
Dimensions
5.25" x 5.65" x 4.80" (133 x 144 x 122 mm)
(W x H x D)
Weight
Aluminum: 5.1 lbs (2.3 kg)
Stainless Steel: 9.4 lbs (4.3 kg)
Warranty
3 years parts and labor. See Warranty
Information and Terms & Conditions on
www.predig.com for complete details.

PD6908 Explosion-Proof & Intrinsically Safe Loop-Powered Process Meter
Instruction Manual
14
Enclosure
Material
-AL Models:
ASTM A413 LM6 die-cast aluminum,
copper-free, enamel coated.
-SS Models:
ASTM A743 CF8M investment-cast
316 stainless steel
Gasket
Fluoroelastomer
Rating
NEMA 4X, IP68 Explosion-proof
Color
-AL: Blue; -SS: Silver
Window
Borosilicate glass
Conduits
Two ¾" NPT threaded conduit openings.
M20 conduits are available. See Ordering
Information on page 11 for details.
Conduit
Stopping
Plug
Sold separately. See Ordering Information on
page 11 for details.
Flange
Built-in flange for wall and pipe mounting.
Tamper-Proof
Seal
Enclosure lid may be secured with
tamper-proof seal.
Instrument
Tag Loop
Built-in loop for securing stainless steel tag
Overall
Dimensions
5.25" x 5.65" x 4.80" (133 x 144 x 122 mm)
(W x H x D)
Weight
Aluminum: 4.8 lbs (2.18 kg)
Stainless Steel: 9.0 lbs (4.08 kg)
ATEX &
IECEx
(Enclosure
only)
Flameproof protection
II 2GD
Ex db IIC Gb
Ex tb IIIC Db
IP66/IP68
Tamb: -55°C to +85°C
Certificate No.: Sira 19ATEX1252U
Certificate No.: IECEx SIR 19.0075U
CSA
(Enclosure
only)
Class I, Division 1, Groups A, B, C, D
Class II, Division 1, Group E, F, G;
Class III
Ex db IIC Gb
Ex tb IIIC Db
Class I, Zone 1, AEx db IIC Gb;
Zone 21, AEx tb IIIC Db
IP66/IP68/TYPE 4X
Tamb: -55°C to +85°C
Certificate No.: 80011200
UL
(Enclosure
only)
Class I, Division 1, Groups A, B, C and D
Class II, Division 1, Groups E, F and G
Class III;
Class I, Zone 1, AEx db IIC Gb
Zone 21, AEx tb IIIC
Ex db IIC Gb
Ex tb IIIC Db
IP66/IP68/TYPE 4X
Tamb: -55°C to +85°C
Certificate Number: E518920
Note: The above approvals are for the enclosure only.
See Hazardous Area Approvals on page 17 for approvals on
the entire instrument.
Input
Input
4-20 mA
Accuracy
±0.02% of span ±1 count,
Square root and programmable exponent:
10-100% FS
Voltage Drop
Without backlight: 1.5 V maximum,
With backlight: 4.7 V maximum
Equivalent
Resistance
Without backlight: 75 Ω @ 20 mA
With backlight: 235 Ω @ 20 mA
Input
Overload
Over current protection to 1 A maximum,
Over voltage protection to 30 VDC max
(Between mA+ and mA- / BL-)
Temperature
Drift
25 PPM/°C from -40 to 75°C ambient
Function
PV1: Linear (2-32 points), square root, or
programmable exponent
PV2: Linear (2-32 points) or round horizontal
tank
Low-Flow
Cutoff
0.1 to 999,999 or disable. Point below at which
the display always shows zero.
HART
Transparency
The meter does not interfere with existing
HART communications; it displays the
4-20 mA primary variable and it allows the
HART communications to pass through
without interruption. The meter is not affected if
a HART communicator is connected to the
loop. The meter does not display secondary
HART variables.

PD6908 Explosion-Proof & Intrinsically Safe Loop-Powered Process Meter
Instruction Manual
15
Common Open Collector &
Relay Specifications
Number
Two open collectors & two relays
High or Low
Alarm
User programmable for high or low alarm
Alarm
Deadband
0-100% FS, user programmable
Output
Assignment
Alarm, Timer, Stopwatch, or Disable
Alarm Output
Source
Assign to PV (PV1, PV2) or Digital Input
On & Off Time
Delay
0 to 9,999 seconds
Fail-Safe
Operation
Independent for each open collector and
relay.
Fail-safe on, the output is on under normal
conditions.
Fail-safe off, the output is on under alarm
conditions.
Alarm
Operation
Automatic, automatic with manual override,
latching (manual reset anytime), latching with
reset after cleared (manual reset only after
alarm has cleared)
Alarm
Indication
Programmable: loop-powered red backlight,
flashing display, alarm symbol , bargraph
segment flashes on alarm.
Custom
Alarm
Messages
Programmableforeachrelay/opencollector:
8charactersmaximum;displayed every10secfor
1seconbottomdisplay.Maybe turnedoff.
Alarm
Acknowledge
CapTouch ACK button or external digital
input resets output and screen indication.
Auto
Initialization
When power is applied to the meter, open
collectors and relays will reflect the state of
the input to the meter.
Timer Output
One-shot or Continuous
Off Time Delay: 1 sec to 99:59:59
(hrs:min:sec)
On Time: 1 sec to 99:59:59 (hrs:min:sec)
Stopwatch
Output turns on when started and off when
stopped.
Open Collector Outputs
Rating
Isolated open collector, sinking NPN
5-30 VDC @ 150 mA maximum
Output
Assignment
Pulse, Alarm, Timer, Stopwatch, or Disable
Pulse Output
Source
PV (PV1, PV2) or Test Frequency
Pulse Output
Factor
0.000001 to 999,999.9
Pulse Width
0.5 ms @ 1 kHz; 500 ms @ 1 Hz;
50% duty cycle
Pulse Output
Frequency
1,000 Hz maximum
Quadrature
Pulse Output
Available for Output 2
(90° behind Output 1) 500 Hz max
Alarm Output
Source
Assign to PV (PV1, PV2)
or Digital Input
Solid-State Relays
Rating
250 VAC/VDC @ 0.5 A resistive
38 VA; 250 VAC; 0.3 A pilot duty
(inductive)
13 VA; 250 VDC; 0.3 A pilot duty (inductive)
Noise
Suppression
Metal oxide varistors across outputs
Relay
Assignment
Pump Alternation, Alarm, Timer, Stopwatch
on/off, or Disable
Alarm Output
Source
Assign to PV (PV1, PV2) or Digital Input
Pump
Alternation
Relays may be programmed to alternate with
each pump cycle with an elapsed time
override where the pumps will alternate
regardless of level. Pump alternation time
can be programmed for 0 to 999:59 (hrs:min)
Relay (Pump)
Runtime
Meter will keep track of how long each relay
(pump) has operated and display this
information.
Relay (Pump)
Cycles
Meter will keep track of how many times the
relays (pumps) have cycled and display this
information.
4-20 mA Transmitter Output
Accuracy
±0.05% FS ±0.001mA
Output
Source
PV1, PV2, re-transmit; reverse scaling
allowed
Scaling
Range
1.00 to 23.0 mA
Disable
High impedance state, less than 1 mA
Calibration
Factory calibrated 4.00 to 20.00 mA
Underrange
1.0 mA, 3.5 mA, or 3.8 mA
(If input < 3.5 mA); or Off; user selectable
Overrange
20.5 mA, 20.8 mA, or 23.0 mA
(If input > 20.5 mA); or Off; user selectable
Isolation
500 V input-to-output
Temperature
Drift
0.5 µA/°C max from -40 to 75°C ambient
External Loop
Power Supply
7.0 VDC to 30.0 VDCmaximum
Output Loop
Resistance
10-750 Ω @ 24 VDC; 10-1100 Ω @ 30 VDC
On-Board Digital Input
Function
Remote acknowledge/reset relays, reset
max/min values, etc. See User section of
Display Functions & Messages on page 28
for a complete list of capabilities.
Contacts
2.1 VDC on contact. Connect normally open
contacts across DI+ and DI-
Logic Levels
Logic High: 2.4 to 30 VDC (max)
Logic Low: 0 to 0.9 VDC

PD6908 Explosion-Proof & Intrinsically Safe Loop-Powered Process Meter
Instruction Manual
16
MeterView XL Software
Availability
Free download from www.predig.com
System
Requirements
Microsoft®Windows®7 & 10
Communicati
ons
USB 2.0 (Standard USB A to Micro USB B)
Cableprovided
Configuration
Configure all parameters on the meter.
Configure meters one at a time.
Configuration
Files
Generate with or without meter connected;
Save to file for later use.
USB Power
Connection
Meter is powered by USB connection during
programming, if 4-20 mA loop is not
connected.
•The meter should only be connected to a computer while
it is located in a safe area
Compatibility
Programs created for Loop Leader and
Loop Leader+ may be run on either
meter. Programs created for
VantageView+ and ProtEX+ can be run
on either meter. No other program
sharing is permissible.
To download the latest MeterView XL programming
software and manual, visit predig.com/meterviewxl.

PD6908 Explosion-Proof & Intrinsically Safe Loop-Powered Process Meter
Instruction Manual
17
Compliance Information
Electromagnetic Compatibility
EMC Emissions
•CFR 47 FCC Part 15 Subpart B Class A
emissions requirements (USA)
•ICES-003 Information Technology
emissions requirements (Canada)
•AS/NZS CISPR 11 Group 1 Class A
ISM emissions requirements
(Australia/New Zealand)
•EN 55011 Group 1 Class A ISM
emissions requirements (EU)
•EN 61000-6-4 Emissions requirements
for Heavy Industrial Environments -
Generic
EMC Emissions
and Immunity
EN 61326-1 EMC requirements for
Electrical equipment for measurement,
control, and laboratory use –industrial use
Hazardous Area Approvals
CSA
Explosion-proof for use in:
Class I, Division 1, Groups B, C and D
Dust-ignition proof for use in:
Class II/III, Division 1, Groups E, F and G; T6
Flame-proof for use in:
Zone 1, Ex d IIC T6
Ta = -55 to 75°C.
Enclosure: Type 4X & IP66/IP68.
Certificate number: 2325749
ATEX
Intrinsically safe for use in:
II 1 G D
Ex ia IIC T4 Ga
Ex ia IIIC T200°C Da
Ta = -55 to 75°C
Enclosure: Type 4X & IP66/IP68
Install per Control Drawing DW2636
(contained within LIM6908-2)
Certificate number: CML 18ATEX2089X
Explosion-proof for use in:
II 2 G D
Ex db IIC T6 Gb
Ex tb IIIC T85°C Db IP68
Ta = -55 to 75°C
Certificate number: Sira 10ATEX1116X
IECEx
Intrinsically safe for use in:
Ex ia IIC T4 Ga
Ex ia IIIC T200°C Da
Ta = -55 to 75°C
Enclosure: Type 4X & IP66/IP68
Install per Control Drawing DW2636
(contained within LIM6908-2)
Certificate number: IECEx CML 18.0050X
Explosion-proof for use in:
Ex db IIC T6 Gb
Ex tb IIIC T85°C Db IP68
Ta = -55 to 75°C
Certificate number: IECEx SIR 10.0056X
ATEX/IECEx Special Conditions for Safe Use
The following conditions relate to safe installation
and/or use of the equipment.
•The equipment loop/power port shall be connected
to an intrinsically safe barrier with Uo ≥ 5.8V
•The 4-20 mA input port shall be connected to an
intrinsically safe barrier with Uo ≥ 5.1V
•The PD6928-HA-AL enclosure is manufactured from
aluminum. In rare cases, ignition sources due to
impact and friction sparks could occur. This shall be
considered during installation, particularly if the
equipment is installed in a Zone 0 location.
•All cable entries into the equipment shall be via cable
glands or conduit which provide a minimum degree
of protection of IP54.
•The equipment may not have 500V isolation
between the circuit and earth. This shall be taken
into account when installing the equipment.
•The equipment label and epoxy coating may
generate an ignition-capable level of electrostatic
charges under certain extreme conditions. The user
should ensure that the equipment is not installed in a
location where it may be subjected to external
conditions (such as high-pressure steam) which
might cause a buildup of electrostatic charges on
non-conducting surfaces. Additionally, cleaning of
the equipment should be done only with a damp
cloth.
•Flameproof joints are not intended to be repaired.
•All entry closure devices shall be suitably certified as
“Ex d”, “Ex t” and “IP66/68” as applicable. Suitable
thread sealing compound (non-setting, non-
insulating, non-corrosive, not solvent based, suitable
for the ambient rating) must be used at the NPT
conduit entries to achieve the IPx8 rating while
maintaining the Ex protection concept.
Year of Construction
This information is contained within the serial number
with the first four digits representing the year and
month in the YYMM format.
For European Community:
The PD69XX Series must be installed in accordance
with the ATEX directive 2014/34/EU, the product
certificates CML 18ATEX2089X, Sira 10ATEX1116X,
IECEx CML 18.0050X, IECEx SIR 10.0056X and the
product manual.

PD6908 Explosion-Proof & Intrinsically Safe Loop-Powered Process Meter
Instruction Manual
18
EU Declaration of
Conformity
For shipments to the EU and UK, a Declaration of
Conformity was printed and included with the product.
For reference, a Declaration of Conformity is also
available on our website www.predig.com/docs.
Safety Information
•Read complete instructions prior to installation
and operation of the meter.
•Hazardous voltages exist within enclosure.
Installation and service should be performed only
by trained service personnel.
•Service requiring replacement of internal
components must be performed at the factory.
•Control room equipment must not use or
generate more than 250 VRMS or VDC.
•Hazardous location installation instructions for
associated apparatus (barrier) must be followed
when installing this equipment.
•For safe installation of an ATEX approved
transmitter in series with PD6908 loop-powered
process meters, the hazardous location
installation instructions for the transmitter,
PD6908 loop-powered process meter, and
associated apparatus (barrier) must be
compatible.
•PD6908 loop-powered process meters do not
add capacitance or inductance to the loop under
normal or fault conditions.
•Substitution of components may impair
hazardous location safety.
•Equipment contains non-metallic materials and
therefore special care and consideration should
be made to the performance of these materials
with respect to chemicals which may be present
in a hazardous environment.
Installation
To access the connectors, remove the enclosure
cover and unclip the display module by pulling it from
the enclosure. The display module may be
disconnected from the options module to facilitate
wiring to the options module.
Refer to Control Drawing DW2636 (contained within
LIM6908-2) for details related to intrinsically safe field
wiring.
Explosion-Proof / Dust-Ignition Proof / Flame-Proof
•Disconnect from supply before opening
enclosure. Keep cover tight while circuits are live.
Conduit seals must be installed within
18" (450mm) of the enclosure.
Unpacking
Remove the meter from box. Inspect the packaging
and contents for damage. Report damages, if any,
to the carrier.
If any part is missing or the meter malfunctions,
please contact your supplier or the factory for
assistance.

PD6908 Explosion-Proof & Intrinsically Safe Loop-Powered Process Meter
Instruction Manual
19
Mounting
The PD6908 has a slotted mounting flange that may
be used for pipe mounting or wall mounting.
Alternatively, the unit may be supported by the
conduit using the conduit holes provided. Refer to
Figure 1and Figure 2.
•Do not attempt to loosen or remove flange bolts
while the meter is in service.
Dimensions
Figure 1. Enclosure Dimensions –Front View
Figure 2. Enclosure Dimensions –Side View
Figure 3. Enclosure Dimensions –Top View
Cover Jam Screw
The cover jam screw should be properly installed
once the meter has been wired and tested in a safe
environment. The cover jam screw is intended to
prevent the removal of the meter cover in a flame-
proof environment without the use of tools. Using a
M2 hex wrench, turn the screw clockwise until the
screw contacts the enclosure’s base. Turn the screw
an additional 1/4 to 1/2 turn to secure the cover.
•Excess torque may damage the threads, screw
head, and/or wrench.
5.25" (133 mm)
3.35" (85.1 mm)
2.25"
(57.2 mm) 0.32"
(8.2 mm)
5.65"
(144 mm)
4.80"
(122 mm)

PD6908 Explosion-Proof & Intrinsically Safe Loop-Powered Process Meter
Instruction Manual
20
Connections
To access the connectors, remove the enclosure cover and unclip the display module by pulling it from the enclosure.
Signal, backlight, open collector, and digital input connections are made to removable connectors on the display
module. Relays and 4-20 mA output connections (if installed) are made to removable connectors on the options
module mounted in the base of the enclosure. The display module may be disconnected from the options module to
facilitate wiring to the options module. Grounding connections are made to the two ground screws provided on the
base of the enclosure, one internal and one external.
•Observe all safety regulations. Electrical wiring should be performed in accordance with all agency
requirements and applicable national, state, and local codes to prevent damage to the meter and ensure
personnel safety.
•Static electricity can damage sensitive components.
•Observe safe handling precautions for static-sensitive components.
•Use proper grounding procedures/codes.
•If the meter is installed in a high voltage environment and a fault or installation error occurs, high voltage may
be present on any lead or terminal.
Display & Options Modules
The display module snaps into built-in rails on the enclosure ensuring a secure and perfect fit every time. No tools are
needed to install or remove it. The options module is screwed into the base of the enclosure. Both modules
completely encase the printed circuit boards.
Options Board (Left) and Display Module (Right)
Options Board Connected to Display Module
Options Board Mounted on the Bottom of Enclosure
Display Module Mounted on Built-In Rails