Canadian Standards Association Atmosphères ExplosiblesEuropean ConformityIECEx Approval


The PD685 is an easy to use, loop-powered indicator, certified by CSA, ATEX and IECEx as intrinsically safe. The PD685 carries international certifications under both the Class/Division System and Zone System, and is thereby suitable for use in gas and dust hazardous areas worldwide. For Division 2 applications where intrinsically safe interfaces are not needed, the PD685 is able to be installed without barriers! To achieve this ability, the PD685 underwent a special 'nonarcing assessment' under the UL 121201 and CSA C22.2 No. 213 standards, and was determined to be a device incapable of causing an ignition on its own. The PD685 is wellsuited for both indoor and outdoor applications and carries a variety of environmental ratings, including Type 4X and IP67.

The PD685 can be seen from considerable distance in bright sunlight or dimly lit areas when the standard backlight feature is activated. The fact that this meter is loop-powered means that there is no need to run additional, costly power lines into a hazardous area. The meter gets all of the power it needs from the 4-20 mA loop and its 1 V (4 V with backlight) drop results in a minimal burden on the loop. The meter features a wide -40 to 75°C operating temperature range and is available with a ½" conduit hole in a location of your choice for easy installation. Calibration is a quick two-step process involving the adjustment of only two sets of coarse and fine, non-interacting potentiometers.


  • Type 4X, IP67 Loop-Powered Field-Mount Process Meter
  • 4-20 mA Input
  • 1.1" (28 mm) 3½ Digits LCD Display; -1999 to 1999
  • 1 V Drop (4 V Drop with Backlight)
  • HART® Protocol Transparent
  • Loop-Powered Backlight Standard
  • Operates from -40 to 75°C (-40 to 167°F)
  • Coarse and Fine Zero & Span Potentiometer Adjustments for Easy Field Scaling
  • Plastic Type 4X, IP67 Enclosure
  • CSA, ATEX and IECEx Certified as Intrinsically Safe
  • CE Marked
  • Conformal Coated PCBs for Dust and Humidity Protection
  • One ½" Conduit Hole (Rear, Top, Bottom or None)
  • Pipe & Panel Mounting Kits
  • Stainless Steel Tag Available
  • 3-Year Warranty

Why Use Loop-Powered Meters?

The most basic decision a user wishing to display a 4-20 mA signal on a digital display has to make is: should the meter be powered by line voltage or should it be powered by the 4-20 mA loop?

There are three main benefits of using loop-powered devices:

  • No additional power required
  • Easy wiring
  • Additional digital displays can easily be added in the same loop

The following diagram illustrates how a loop-powered meter is wired. Notice there are only two connections made to the meter.

Loop-Powered Connections

For more information on loop-powered meters, check out Fundamentals of Loop-Powered Devices and Loop-Powered vs Line-Powered Meters white papers.

Except where noted all specifications apply to operation at +25°C.

Input4-20 mA @ 30 VDC maximum
Display1.1" (28 mm) LCD, 3½ digits; -1999 to +1999
BacklightPowered by 4-20 mA loop. Intensity varies with signal level
Accuracy±0.1% FS ±1 count
ApprovalsATEX and IECEx:
Certified as intrinsically safe with entity, for use in Equipment Group II, categories 1G (for Gas) and 1D (for Dust), suitable for Zone 0, 1 & 2 (for Gas) and Zone 20, 21 & 22 (for Dust) classified areas, and carrying the following markings:
ATEX II 1 GD. Ex ia IIC T4 Ga. Ex ia IIIC T135°C Da.
-40°C ≤ Ta ≤ +75°C.
ATEX Certificate Number: CML 17ATEX2113X
IECEx Certificate Number: CML 17.0052X
Certified as intrinsically safe with entity, to U.S. and Canadian standards for Divisions and Zones (Gas and Dust), and carrying the following markings:
Ex ia IIC T4 Ga; Ex ia IIIC T135°C Da; (Canada only)
Class I, Zone 0, AEx ia IIC T4 Ga; Zone 20,
AEx ia IIIC T135°C Da; (U.S. only)
Class I, Division 1, Groups A, B, C and D, T4;
Class II, Division 1, Groups E, F and G, T135°C;
Class III; Type 4X; IP67;
-40°C ≤ Ta ≤ 75°C
Certified as suitable for Division 2 without barriers, to U.S. and Canadian Standards, and carrying the following markings:
Class I, Division 2, Groups A, B, C and D, T6;
Class II, Division 2, Groups F and G, T85°C;
Class III; Type 4X; IP67;
-40°C ≤ Ta ≤ 75°C
CSA Certificate Number: 1111348
Entity ParametersUi = 30 V, Ii = 175 mA, Pi = 1 W, Ci = 0, Li = 0
See Control Drawing LIM685-2 (DW2443) for complete installation instructions.
Decimal PointUser selectable via J2 jumper
Calibration4-step coarse & fine control; non-interacting zero & span
Calibration Range4 mA input: -1000 to +1000; 20 mA input: between 20 and 2000 counts > 4 mA display
Display Update Rate2.5/second
Maximum Input Current30 mA
Input Overload ProtectionOver voltage protection to 30 V max (between S+ and S-)
Maximum Voltage Drop1 V @ 20 mA (4 V @ 20 mA with backlight)
Operating Temperature-40 to 75°C
Storage Temperature-40 to 85°C
Relative Humidity0 to 90% non-condensing.
Printed circuit boards are conformally coated.
EnclosureImpact-resistant, glass-filled, polycarbonate body, opaque; Impact-resistant, polycarbonate cover, transparent; Polyurethane/polymer gasket; Polyamide/plastic cover screws; Type 4X, IP67
ConnectionsRemovable screw terminals accept 12 to 26 AWG
Conduit HoleOne 22 mm (0.865") conduit hole to allow a 1/2" NPT connection may be provided; refer to Ordering Information to specify hole location;
request model (-Z) for no conduit hole.
Overall Dimensions5.12" x 3.15" x 2.75" (W x H x D)
(130 mm x 80 mm x 70 mm)
Weight12 oz (340 g)
Warranty3 years parts and labor. See Warranty Information and Terms & Conditions on for complete details.


  • Figures 1-6 are intended to serve as simplified wiring diagrams for typical applications.
  • For hazardous area applications, the PD685 must be installed per the PD685 Intrinsic Safety Control Drawing (LIM685-2).

Field wiring is made to the back side of the printed circuit board which is mounted in the enclosure.

Calibrator Connection

Figure 1: Calibrator Connection
Calibration Controls Location

Figure 2: Calibration Controls Location
Control Loop Connections (2-Wire) Figure 3: Control Loop Connections (2-Wire)
Control Loop Connections with Backlight (2-Wire) Figure 4: Control Loop Connections
with Backlight (2-Wire)
Control Loop Connections (4-Wire) Figure 5: Control Loop Connections (4-Wire)
Control Loop Connections with Backlight (4-Wire) Figure 6: Control Loop Connections
with Backlight (4-Wire)
  • Electrostatic hazard. Clean only with a moist cloth. Protect enclosure from exposure to chemical solvents and excessive ultraviolet (UV) light (e.g. sunlight).


Units: Inches (mm)

PD685 Dimensions

Dimensions and Wall Mounting Information

Pipe Mounting Kit

The PDA6845-SS is a stainless steel pipe mounting kit with two mounting holes. It provides all of the necessary hardware to mount the PD685 to a 2" pipe.

PD6845 Pipe Mounting Kit

PDA6845-SS Pipe Mouting Kit

Panel Mounting Kit

The PDA6854 is a panel mounting kit for the PD685. It provides all of the necessary hardware to mount the PD685 meter to an equipment panel. This panel mounting kit is not intended to provide waterproof protection to the panel.

PD685 Panel Mounting Kit

PDA6854 Panel Mouting Kit

Choose Your Options

Configurations other than those specified above are available at a $250 adder. Consult factory for desired model number and price.

Why you should buy: