PD6622 and PD6624 Rate Totalizers

The Loop Leader PD6620 is a loop-powered, 1/8 DIN flow rate/totalizer designed for demanding process control applications. The four front panel buttons make setup and programming of the meter simple and intuitive. A dual-line display featuring five digits on the top line and eight digits on the bottom line, preprogrammed engineering units, and optional bargraph display (PD6624) provide a clear and attractive presentation of the process. The units of measure can be changed as needed (e.g. gallons/second to liters/second) without the need to re-scale the meter.

The dual-line display can be customized by the user to operate in such a way as to satisfy a specific application. Typically, the top line is used for the rate while the bottom line is used for the total, grand total, or engineering units. Three programmable function keys and a digital input come standard and allow the meter to be customized for use in specialized applications.

All models come equipped with two open collector outputs and are available with two solid state relays and a 4-20 mA analog output. These outputs can be programmed for alarm indication, signal retransmission via pulse or analog signal, pump control, and a number of other useful features.

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 Loop Leader loop-powered rate/totalizer is built in a shallow-depth case with a IP65 front and features loop-powered backlighting and a wide -40 to 167°F (-40 to 75°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.


  • Loop-Powered Backlight with Red Backlight for Alarm Conditions
  • Loop-Powered Rate/Totalizer
  • Display rate & total simultaneously
  • Total display includes commas for more intuitive readings
  • 1.5 Volt Drop (4.7 Volt Drop w/ Backlight)
  • IP65 Front
  • -40 to 167°F (-40 to 75°C) Operating Temperature Range
  • Five Digit Top Line
  • Alphanumeric tag names
  • Total, Grand Total, or Non-Resettable Grand Total
  • Up to 13-digit total & grand total
  • Dual Line Display
  • 1/8 DIN Shallow Depth Case
  • Optional Loop-Powered Solid State Relays
  • Optional 4-20 mA Analog Output
  • Open Collector Output Standard
  • Optional Bargraph Display (PD6624)
  • Batch control relay operation
  • Timer functions for open collectors and relays
  • Relay runtime and cycle count
  • Multi-Point Linearization, Square Root, and Programmable Exponent Input Conditioning Functions
  • Enter initial total & grand total count

PD6624 Rate/Totatlizer with Bargraph

PD6624 Rate Totalizers with Bargraph

Display with Bargraph Option

The Loop Leader offers not only the typical decimal display, but it offers another model with an added bargraph to provide a clear and attractive presentation of the process. This makes reading your process quick, convenient, and easy-to-understand.
PD6624 Rate Totalizers with Bargraph

Display Flow Rate, Total or Grand Total

Typically, the top line on the display can be programmed to display flow rate and the bottom line total, grand total, or engineering units. See examples on the right of how you can set up the meter.
PD6624 Rate Totalizers with Bargraph


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



Top: 0.7” (17.8 mm), Bottom: 0.4” (10.2 mm); 14-segment alphanumeric

Top: 5 digits -9999 to 99999

Bottom: 8 digits -9,999,999 to 99,999,999

Bottom line separated by commas

Update Rate

Ambient > -10°C: 1 Update/Second

Ambient > -20°C: 1 Update/2 Seconds

Ambient -40°C: 1 Update/10 Seconds


Top: 99999; Bottom: 99,999,999 (flashing)


Top: -9999; Bottom: -9,999,999 (flashing)

Programming Method

Front panel

Noise Filter

1, 2, 4, 8, 16 sec.

Noise Filter Bypass

0.1 to 99.9% FS


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.


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


Operating temperature range: -40 to 75°C
Storage temperature range: -40 to 85°C
Relative humidity: 0 to 90% non-condensing


Removable screw terminals accept 12 to 22 AWG wire

DI Digital Input Contacts

2.1 VDC on contact. Connect normally open contacts across DI+ to DI-

DI Digital Input Logic Levels

Logic High: 2.4 to 30 VDC (max)

Logic Low: 0 to 0.9 VDC

Enclosure &

1/8 DIN, high impact plastic, NORYL® Polyphenylene Ether & Polystyrene blend (PPE PS) Resin, UL 94V-0, color: gray

Gasket: Silicone Rubber

Faceplate: LEXAN® Polycarbonate (PC) Film

Buttons: Silicone rubber; Color: black


1/8 DIN panel cutout required. Two panel mounting bracket assemblies provided

Tightening Torque

Screw terminal connectors: 4.5 lb-in (0.5 Nm)
Mounting screws: 8.0 lb-in max. (0.9 Nm)


4.68" x 2.45" x 3.79" (119 mm x 62 mm x 96 mm) (W x H x D)


8.7 oz (247g) w/ option board


3 years parts and labor

Process Input


±0.02% of span ±1 count, Square root and programmable exponent: 10-100% FS


Linear, square root, or programmable exponent

Low-Flow Cutoff

0.0 to 999,999.9

Temperature Drift

25 PPM/°C from -40 to 75°C ambient

Decimal Point

Up to four decimal places: On top

Up to seven decimal places: On bottom

Scaling and Display Range

Input: 4-20 mA

Scaling Range: -999,999.9 to 999,999.9

Display Range: Top Line: -9999 to 99999; Bottom Line: -9,999,999 to 99,999,999

Voltage Drop

With backlight off: 1.5 V max

With backlight on: 4.7 V max

Equivalent Resistance

With backlight off: 75 Ω @ 20 mA

With backlight on: 225 Ω @ 20 mA

Input Overload

Over current protection to 1 A maximum


Rate Display Indication

-9999 to 99999, top display
-9,999,999 to 99,999,999, bottom display

Total Display & Total Overflow

-9999 to 99999, top display
-9,999,999 to 99,999,999, bottom display
“T” LCD segment shows while displaying total

“G T” LCD segments show for grand total.

(non-bargraph display version only)
Up to 9,999,999,999,999 with 13-digit feature. Total or grand total flashes and a truncated value is shown. Press function key assigned to display (default: F1) to view full number.

Total Decimal Point

Up to four decimal places: On top
Up to seven decimal places: On bottom
Total decimal point is independent of rate decimal point.


Calculates total based on rate and rate units to display total in engineering units. A custom factor must be programmed if using custom defined units.

Totalizer Rollover

Totalizer rolls over when display exceeds 99,999,999 (9,999,999,999,999 if 13-digit limit enabled). Relay status reflects display.

Total Reset

Via front panel button or external contact closure on digital input

Total Reset Password

Total and grand total passwords may be entered to prevent resetting the total or grand total from the front panel.

Non-Resettable Total

Total and grand total reset may be disabled through the meter interface

Open Collector Output


Two NPN, Isolated open collector, 30 VDC @ 90 mA maximum

Output Assignment

Pulse, Alarm, Timer, Total Reset, or Disable

Pulse Output Source

Rate, Total, Grand Total, or Test Frequency

Pulse Output Factor

0.000001 to 999,999.9

Pulse Width

Min: 2 ms @ 250 Hz; 50% duty cycle
Max: 250 ms @ < 2 Hz

Pulse Output

250 Hz maximum
0.1 Hz minimum

Quadrature Pulse Output

Available for Output 2 (90° behind Output 1)

Alarm Output Source

Assign to Rate, Total, Grand Total or Digital Input

High or Low Alarm

User programmable for high or low alarm

Alarm Deadband

0-100% FS, user programmable

On & Off Time Delay

0 to 9,999 seconds


Independent for each output

Alarm Operation

Auto, Auto-man, Latch, Latch w/clear

Alarm Indication

Red backlight, Flashing display, Alarm Message, Alarm symbol (!)

Alarm Message

On or Off; User programmable, 8 characters maximum

Displayed every 10 sec for 1 sec on bottom

Alarm Acknowledge

Front panel ACK button or external digital input resets output and screen indication

Auto Initialization

When power is applied to the meter, 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)

Timer Start/Stop

Front panel or digital input, user se-lectable

Solid State Relays


Resistive Load: 250 VAC/DC @ 1 Amp

Inductive Load: 1/10 HP @ 125/250 VAC/DC


Metal oxide varistors across outputs


Alarm, Timer, Batch Control, Sample, or Disable

Alarm Output Source

Assign to Rate, Total, Grand Total, or Digital Input

High or Low Alarm

User programmable for high or low alarm

Alarm Deadband

0-100% FS, user programmable

On & Off Time Delay

0 to 9,999 seconds

Fail-Safe Operation

Independent for each relay

Alarm Operation

Auto, Auto-man, Latch, Latch w/clear

Timer Start/Stop

Front panel or digital input, user se-lectable

4-20 mA Transmitter Output

Output Source

Rate, total, re-transmit; reverse scaling allowed

Scaling Range

1.00 to 23.0 mA


High impedance state, less than 1 mA


Factory calibrated 4.00 to 20.00 mA


1.0 mA, 3.5 mA, or 3.8 mA (If input < 3.5 mA), or Off; user selectable


20.5 mA, 20.8 mA, or 23.0 mA (If input > 20.5 mA), or Off; user selectable


500 V


±0.05% FS ±0.001mA

Temperature Drift

0.5 µA/°C max from -40 to 75°C ambient

External Loop Power Supply

7.0 VDC to 30.0 VDC maximum

Output Loop

10-750 Ω @ 24 VDC; 10-1100 Ω @ 30 VDC

Mounting Dimensions

  1. Panel cutout required: 1.772" x 3.622" (45mm x 92mm)
  2. Panel thickness: 0.040 - 0.250" (1.0mm - 6.4mm)
  3. Mounting brackets lock in place for easy mounting
  4. Clearance: Allow 6" (152 mm) behind the panel


Open Channel Flow

The PD6622/24, in combination with an ultrasonic level transmitter, makes for an economical way to measure and display open channel flow rate and total in most weirs and flumes and take periodic samples.

Differential Pressure Flow

The PD6622/24 can display flow rate and total by extracting the square root from the 4-20 mA signal from a differential pressure transmitter. The user selectable low-flow cutoff feature gives a reading of zero when the flow rate drops below a user selectable value.

  • Display Flow Rate
  • User Selectable Low-Flow Cutoff
  • Only 2 Calibration Points Required


Connectors Labeling

The connectors' label, affixed to the meter, shows the location of all connectors available with requested configuration.

Current Loop (4-20 mA) Connections

The following figures show a 4-20 mA current loop connected to the meter. The first figure shows the connection with the backlight disabled and the second shows the connection with the backlight enabled. The meter is powered by the 4-20 mA current loop.

Digital Input Connection

A digital input is standard on the meter. This digital input is connected with a normally open contact across DI+ and DI-, or with an active low signal applied to DI+.

4-20 mA Output Connections

Connections for the 4-20 mA transmitter output are made to the connector terminals labeled MA OUT. The 4-20 mA output must be powered from an external power supply.

Relay Connections

Relay connections are made to two four-terminal connectors. Each relay's C terminal is common only to the normally open (NO) contact of the corresponding relay.

Open Collector Outputs

Open collector output 1 and 2 connections are made to terminals labeled O1+ and O1-, and O2+ and O2-. Connect the alarm or pulse input device as shown below.

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Why you should buy:

  • Loop-Powered Rate/Totalizer
  • Bargraph Display (Optional)
  • 1/8 DIN Panel Mount
  • Open Collector Outputs Standard
  • Solid State Relays (Optional)
  • 4-20 mA Output (Optional)