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Instructions 

APD 2003

Calibration

Input and output ranges are factory pre-configured (at 24°C 
±1°C).  Front-mounted Zero and Span potentiometers for 
each channel can be used to compensate for load and lead 
variations.
1.  Apply power to the module and allow a minimum 30 minute 

warm up time.

2. Using an accurate calibration source, provide an input to 

the module equal to the minimum input required for the 
application.

3. Using an accurate measurement device for the output, 

adjust the Zero potentiometer for the exact minimum output 
desired. The Zero control should only be adjusted when the 
input signal is at its minimum. This will produce the cor-
responding minimum output signal. For example: 4 mA for 
a 4-20 mA output or –10 V for a ±10 V output.

4.  Set the input at maximum, and then adjust the Span pot for 

the exact maximum output desired. The Span control should 
only be adjusted when the input signal is at its maximum. 
This will produce the corresponding maximum output 
signal. Example: for 4-20 mA output, the Span control will 
provide adjustment for the 20 mA or high end of the signal.

5.  Repeat adjustments for both output channels for maximum 

accuracy.

Output Test Function

When the Test button is depressed it will drive the output with a 
known good signal that can be used as a diagnostic aid during 
initial start-up or troubleshooting. When released, the output 
will return to normal.
Each Test Cal. potentiometer is factory set to approximately 
50% output. Each can be adjusted to set the test output from 
0 to 100% of the output span. Press and hold the Test button 
and adjust the corresponding Test Cal. potentiometer for the 
desired output level.
They may optionally be externally wired for remote test opera-
tion or a manual override. See wiring diagram at right.

Operation

The APD 2003 accepts two independent DC voltage or current 
inputs and provides two independent and optically isolated DC 
voltage or current outputs that are linearly related to each input. 
Green LoopTracker

®

 input LEDs provide a visual indication that 

each signal is being sensed by the input circuitry of the module. 
They also indicates the input signal strength by changing in 
intensity as the process changes from minimum to maximum.
If an LED fails to illuminate, or fails to change in intensity as 
the process changes, check the module power or signal input 
wiring. Note that it may be difficult to see the LEDs under bright 
lighting conditions.
Two red LoopTracker output LEDs provide a visual indication 
that the output signals are functioning. They become brighter 
as the input and each corresponding output change from 
minimum to maximum. 
For a current output the red LED will only light if the output loop 
current path is complete. For either current or voltage outputs, 
failure to illuminate or a failure to change in intensity as the 
process changes may indicate a problem with the module 
power or signal output wiring. 

14

13

15 16

10

9

11 12

External 

Contacts  

for Test 

Function

– 

+ 20V

– 

+ 20V

mA 

Device 2

R

i

mA 

Device 1

R

i

6

5

7

8

2

1

3

4

Ch. 1

Ch. 2

Voltage 

Output

– 

+

Voltage 

Device 1

– 

+

Voltage 

Device 2

2

1

3

4

Ch. 1

Ch. 2

6

5

7

8

– 

+

mA 

Device 2

R

i

Loop 

Power 

Source 2

– 

+

+

 –

mA 

Device 1

R

i

Loop 

Power 

Source 1

Ch. 1

Ch. 2

2

1

3

4

6

5

7

8

+

 –

APD 2003

 

Channel 1 

Channel 2 

 

DC to DC  

Potentiometer to DC 

  Isolated Transmitter 

Isolated Transmitter

Test Cal.

Span

Zero

Test

Output

Loop
Tracker

Test Cal.

Span

Zero

Test

Output

Input

Loop
Tracker

Loop
Tracker

Input

Loop
Tracker

Channel 1

Channel 2

®

28 Power AC or DC –
26 Earth Ground
25 Power AC or DC +

26

25

27

28

18

17

19

20

Voltage 

Xmtr 1

– 

+

Ch. 1 

Voltage Input

22

21

23

24

Ch. 2

21 Full Scale* 
22 Minimum*
23 Wiper Arm

*May be 

switched for 

reverse output

DC Input Channel 1

Terminal Terminal

Sensor or transmitter with voltage output.

17 (

–)

19 

(

+)

mA output transmitter that powers the cur-

rent loop. Typically a 3 or 4-wire device.

17 (

–)

19 

(

+)

Transmitter with an unpowered mA 

output. Typically a 2-wire device. APD 

module provides loop power.

19 (

–) 1

(

+15 V)

Input 1, DC

For milliamp ranges determine if your devices provide power 
to the current loop or if the loop must be powered by the APD 
module. Typical voltage may be 9-24 VDC at your device's 
terminals if it provides power to the loop.

Input 2, Potentiometer

The potentiometer must be connected to all three signal input 
terminals as shown. 0-100% of the potentiometer range must 
be used. A stable 1 VDC source to excite the potentiometer. 
Voltage drop is measured across the potentiometer, thus allow-
ing any full-range potentiometer to be used.

Potentiometer Input Channel 2

 Terminal

Full scale or high side of potentiometer

 21 

(

+1 VDC)

Zero or low end of potentiometer

  22 (–)

Potentiometer wiper arm

 23

To maintain 

full isolation 

avoid com-

bining power 

supplies in 

common with 

inputs, out-

puts, or unit 

power.

Mounting to a DIN Rail

Install module vertically on a 35 mm DIN rail in a protective 
enclosure away from heat sources. Do not block air flow. Allow 
1" (25 mm) above and below housing vents for air circulation.
1.  Tilt front of module down and 

position the lower spring clips 
against the bottom edge of DIN rail.

2.  Push front of module upward until 

upper mount snaps into place.

Removal

Avoid shock hazards! Turn signal 
input, output, and power off.
1.  Push up on bottom back of module.
2. Tilt front of module downward 

to release upper mount from top 
edge of DIN rail. 

3.  The module can now be removed 

from the DIN rail.

Spring Clips

Upper Mount

Precautions

WARNING! All wiring must be performed by a qualified electri-
cian or instrumentation engineer. See diagram for terminal des-
ignations and wiring examples. Consult factory for assistance. 
WARNING! Avoid shock hazards! Turn signal input, output, and 
power off before connecting or disconnecting wiring, or remov-
ing or installing module.

Précautions

ATTENTION! Tout le câblage doit être effectué par un élec-
tricien ou ingénieur en instrumentation qualifié. Voir le dia-
gramme pour désignations des bornes et des exemples de 
câblage. Consulter l'usine pour assistance.
ATTENTION! Éviter les risques de choc! Fermez le signal 
d'entrée, le signal de sortie et l'alimentation électrique avant 
de connecter ou de déconnecter le câblage, ou de retirer ou 
d'installer le module. 

Electrical Connections

Polarity must be observed for signal wiring connections. If the 
input and/or output do not function, check wiring and polarity.
Each product is factory configured to your exact input and 
output ranges as indicated on the serial number label. 

Outputs

For milliamp ranges determine if your devices provide power 
to the current loop or if the loop must be powered by the APD 
module. Typical voltage may be 9-24 VDC at your device's 
terminals if it provides power to the loop.

Device for Output Channel 1

Terminal Terminal

Measuring/recording device accepts a 

voltage input.

3 (

–)

(

+)

Measuring/recording device has 

an unpowered or passive mA input. 

 

APD module provides the loop power.

3 (

–)

(+20 V)

Measuring/recording device has a mA 

input and powers the current loop. 

2 (

–)

(

+)

Device for Output Channel 2

Terminal Terminal

Measuring/recording device accepts a 

voltage input.

7 (

–)

(

+)

Measuring/recording device has 

an unpowered or passive mA input. 

 

APD module provides the loop power.

7 (

–)

(+20 V)

Measuring/recording device has a mA 

input and powers the current loop. 

6 (

–)

(

+)

Module Power Terminals

Check model/serial number label for module operating voltage to 
make sure it matches available power. The power supplies are fuse 
protected and the unit may be returned to API for fuse replacement.
When using DC power, either polarity is acceptable, but for consis-
tency, wire positive (+) to terminal 25 and negative (–) to terminal 28.

Cu 60/75°C 

conductors 

14 AWG 

max.

api-usa.com

1220 American Way Libertyville, IL 60048 
Phone: 

800-942-0315

 

Fax: 800-949-7502

A

A

BSOLUTE

BSOLUTE

 P

 P

ROCESS

ROCESS

 I

 I

NSTRUMENTS

NSTRUMENTS

Wire terminal 

torque 

0.5 to 0.6 Nm or 

4.4 to 5.3 in-lbs

API maintains a constant effort to upgrade and improve its products. 

Specifications are subject to change without notice. See api-usa.com for 

latest product information. Consult factory for your specific requirements.

WARNING:

 This product can expose you to chemicals includ-

ing nickel, which are known to the State of California to cause 

cancer or birth defects or other reproductive harm. For more 

information go to www.P65Warnings.ca.gov

Current 

Sourcing 

Output

Current 

Sinking 

Output

Module 

powers mA 

output loop

Module mA 

output is  

unpowered

18

17

19

20

+15V

 –

mA 

Xmtr 1

R

i

Ch. 1 

Current sourcing input 

Module powers loop

18

17

19

20

+

mA 

Xmtr 1

R

i

Loop 

Power 

Source 1

+

Ch. 1 

Current sinking input 

Input externally powered

To avoid 

damage to 

the module, 

do not 

make any 

connections 

to unused 

terminals

3 or 4 wire 

mA transmit-

ter or 2 wire 

w. power 

supply

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