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PD684 Loop Leader Loop-Powered Flow Rate/Totalizer Digital Panel Meter

USA Toll Free: 1-800-730-0302 Tel: 416-240-1920 -

The Loop Leader PD684 is a loop-powered, 1/8 DIN flow rate/totalizer designed for demanding process control applications. The fact that this meter is loop-powered means that there is no need to run additional, costly power lines; the meter gets all of the power it needs from the 4-20 mA loop. The PD684 loop-powered rate/totalizer is built in a shallow-depth case with an FM Type 4X front and features loop-powered backlighting and a wide -30 to 65°C operating temperature range. It doesn't matter if it's indoors or outdoors, in bright sunlight or a dimly lit plant, or in an area that is wet, dirty, hot, or cold, the Loop Leader can go just about anywhere.


  • 4-20 mA Input
  • 5-Digit LCD, 0.6" (15.2 mm) High
  • Overflow Displays Total up to 8 Digits
  • Programmable Alternating Rate/Total Display
  • FM Type 4X, IP65 Front
  • Shallow Depth Case 3.2" Behind Panel
  • 2 V Drop (5.7 V with Backlight)
  • Loop-Powered Backlight Standard
  • Custom Engineering Units & Bargraph
  • Square Root or Programmable Exponent
  • Non-Volatile Memory - No Battery Needed
  • Maximum & Minimum Display
  • Operating Temperature Range: -20 to 65°C
  • Open Collector Alarm or Pulse Output
  • HART Protocol Transparent

PD684 Loop Leader Loop-Powered Flow Rate/Totalizer Digital Panel Meter Data Sheet
PD684 Loop Leader Loop-Powered Flow Rate/Totalizer Digital Panel Meter Instruction Manual

General Specifications

  • Display: 5-digit LCD (-99999 to 99999), 0.60" (15.2 mm) high, 7-segment, automatic lead zero blanking.
  • Engineering Units: 0.25" (6.4 mm) high, 14-segment.
  • Bargraph: 20-segment, 0% to 100% indication.
  • Trend arrows: Up and down trend indication.
  • Backlight: Bright orange (intensity varies with signal)
  • Front Panel: FM Type 4X, IP65; panel gasket provided
  • Display Update Rate: 2.5/second
  • Overrange: Display flashes 99999
  • Underrange: Display flashes -99999
  • Programming Method: Four front panel buttons
  • Noise Filter: Programmable from 1 to 199
  • Recalibration: 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.
  • Password: Programmable password restricts modification of programmed settings.
  • Non-Volatile Memory: All programmed settings are stored in nonvolatile memory for a minimum of ten years if power is lost.
  • Voltage Drop: 2.0 V max w/o backlight, 5.7 V max with backlight
  • Equivalent Resistance: 125 O @ 20 mA without backlight, 315 O @ 20 mA with backlight.
  • Normal Mode Rejection: 64 dB at 50/60 Hz
  • Operating temperature range: -20 to 65°C
  • Allowable temperature range: -40 to 65°C* (see note below)
  • Storage temperature range: -40 to 85°C
  • Relative humidity: 0 to 90% non-condensing
  • Connections: Screw terminals accept 12 to 22 AWG wire
  • Enclosure: 1/8 DIN, high impact plastic, UL 94V-0, color: gray
  • Mounting: 1/8 DIN panel cutout required. Two panel mounting bracket assemblies provided.
  • Tightening Torque: 4.5 lb-in (0.5 Nm) Screw terminal connectors
  • Overall Dimensions: 4.68" x 2.45" x 3.79" (119 x 62 x 96 mm)
  • Weight: 5.7 oz (162 g)
  • Warranty: 3 years parts & labor


  • Input Range: 4-20 mA
  • Accuracy: ±0.03% of span ±1 count, square root and programmable exponent: 10-100% FS.
  • Calibration: Scale without signal or calibrate with signal source
  • Calibration Range: User programmable over entire range of meter
  • Minimum Span: 0.40 mA between input 1 and input 2
    Note: An Error message will appear if input 1 and input 2 signals are too close together.
  • Input Overload: Over current protection to 2 A max.
  • HART Transparency: Analog input will not interfere with existing HART communications on the wired 4-20 mA signal
  • Decimal Point: Up to 4 places (d.dddd, dd.ddd, ddd.dd, dddd.d, or ddddd)
  • Function: Linear, square root, or programmable exponent
  • Low-Flow Cutoff: -99999 to 99999 (-99999 disables cutoff function)
  • Temperature Drift: 50 PPM/°C from -40 to 65°C ambient

Totalizer Features

  • Total Display: 0 to 99,999 main total display plus 0 to 999 total overflow for a combined 8 digit total of 99,999,999.
  • Alternating Display: Display may be programmed to alternate between rate and total every 10 seconds.
  • Time Base: Seconds, minutes, hours, or days
  • Totalizer Conversion Factor: 0.0001 to 99999
  • Totalizer: Calculates total based on rate, time base of second, minute, hour, or day, and field programmable multiplier; stored in non-volatile memory upon power loss.
  • Totalizer Rollover: Total rolls over when total exceed 99,999,999.
  • Totalizer Reset: Manual reset or automatic with time delay, or disabled for non-resettable total applications.

Open Collector Output

  • Rating: Isolated open collector, 30 VDC @ 175 mA max.
  • Alarm Output: Assign to rate or total, high or low rate alarm.
  • Deadband: 0-100% of full scale, user selectable
  • Acknowledge: ACK button resets output and screen indication.
  • Automatic Reset: Alarm resets automatically when signal reaches the reset point.
  • Pulse Output: 250 pulses/sec max; pulse width: 3 ms, fixed. If the pulse output exceeds the maximum pulse output, counts are accumulated as pending and are not lost. One pulse per total
  • increment, programmable from 0.0001 to 99999 (decimal point based on total selection).

* Below -20°C the LCD becomes less readable.

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.


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