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DMD4059 Series Strain Gauge to DC Isolated Transmitter

3

Device Connected to Output Terminal Terminal  Switch E

Voltage input

3 (

–)

(

+)

V

Passive mA (current) input. 

Module provides loop power

3 (

–)

(+20 V)

I

mA (current) input device that  

provides loop power. 

2 (

–)

(

+)

I

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.
The Test Cal. potentiometer can be used to set the test output 
to the desired level. It is adjustable from 0 to 100% of the 
output span.
Press and hold the Test button and adjust the Test Cal. potenti-
ometer for the desired output level.

Installation Precautions

WARNING! Avoid shock hazards! Turn signal input, output, and 
power off before connecting or disconnecting wiring, or remov-
ing or installing module.

Mounting to a DIN Rail

The housing clips to a standard 35 mm DIN rail. The housing is 
IP40 rated and requires a protective panel or enclosure.
Do not block air flow. Allow 1” (25 mm) above and below hous-
ing vents for air circulation.
1.  Tilt front of module downward and position against DIN rail. 
2.  Clip lower mount to bottom edge of DIN rail.
3.  Push front of module upward until upper mount snaps into 

place.

Removal

1.  Push up on the bottom back of the 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.

Operation

Strain gauges and load cells are normally passive devices that 
are commonly referred to as “bridges” due to their four-resistor 
Wheatstone bridge configuration. These sensors require a 
precise excitation source to produce an output that is directly 
proportional to the load, pressure that is applied to the sensor.
The exact output of the sensor (measured in millivolts) is deter-
mined by the sensitivity of the sensor (mV/V) and the excitation 
voltage applied. 
An additional input, the sense lead, monitors the voltage drop in 
the sensor leads and automatically compensates the excitation 
voltage at the module in order to maintain a constant excitation 
voltage at the sensor.
The DMD4059 provides the excitation voltage to the sensors and 
receives the resulting millivolt signal in return. This input signal 
is filtered and amplified, then offset, if required, and passed 
to the output stage. Depending on the output configuration 
selected, a DC voltage or current output is generated.
The green input LED provides a visual indication that a signal 
is being sensed by the input circuitry of the module. It also 
indicates the input signal strength by changing in intensity as 
the process changes from minimum to maximum.
If the 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.
The red output LED provides a visual indication that the output 
signal is functioning. It becomes brighter as the input and the 
corresponding output change from minimum to maximum. 
For current outputs, 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. 

Diagnostic Voltage Measurements

Using a meter with at least 10 megaohm input impedance, measure the voltage coming from the strain gauge at the locations shown. 
Sensitivity is measured in mV/V.

Positive  

Meter Lead

Negative  

Meter Lead

Meter Reading  

No pressure/load

Meter Reading  

Full pressure/load

+ Exc.

– Exc.

Excitation Voltage

Excitation Voltage

+ Sig.

– Exc.

+ ½ Excitation Voltage

½ Excitation V (½ x Excitation Voltage x Sensitivity)

– Sig.

– Exc.

+ ½ Excitation Voltage

½ Excitation Voltage – (½ x Excitation Voltage x Sensitivity)

+ Sig.

– Sig.

Zero Volts

Excitation Voltage x Sensitivity

14

13

15

16

13  Power AC or DC 

+

14 

Earth Ground

16  Power AC or DC –

Module Power

Current sinking output 

switch E set to “I”

External device provides 

power to output loop

2

1

3

4

– 

+

+

 –

Loop 

Power 

Source

+

4-20 mA 

Device

R

i

Current sourcing output  

switch E set to “I”  

+20 V at terminal 4

2

1

3

4

Passive 

4-20 mA 

Device

R

i

– 

+20V

Voltage output  

switch E set to “V”

2

1

3

4

Voltage 

Device

– 

+

Output Wiring

Calibration

The Zero, Span, and Excitation potentiometers are used to 
calibrate the output. 
Note: Perform the following calibration procedure any time 
switch settings are changed.
This calibration procedure does not account for offsets or tare 
weights. If your system has an offset, tare weight or deadweight, 
refer to the "Using Offset Switch C" procedure. 
To achieve optimum results, the system should be calibrated 
using an accurate bridge simulator, pressure calibrator, or cali-
bration weights depending on the application.
1.  Apply power to the module and allow a minimum 20 minute 

warm up time.

2. Using an accurate voltmeter across terminals 10 and 12, 

adjust the excitation voltage potentiometer for the exact volt-
age desired.

3.  Provide an input to the module equal to zero or the minimum 

input required for the application.

4. Using an accurate measurement device for the module 

output, adjust the Zero potentiometer for the exact mini-
mum output signal desired. The Zero control should only be 
adjusted when the input signal is at its minimum.

5.  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. 

6.  Repeat the zero and span calibration for maximum accuracy.

With Sense Leads

Sense 

+

 

Sense –

Sense 

+

 

Sense –

6

5

7

8

10

9

11 12

Strain 

Gauge

V

0

 

+

V

0

 –

V

EX

 –

V

EX

 

+

Exc 

+

Exc –

Sig 

Sig 

+

Sig 

+

Exc –

Sig –

Exc 

+

Test Cal.

Span

Zero

Test

Output

Input

DMD4059

Strain Gauge to DC

Isolated Transmitter

LED

Excitation

LED

OMEGA Engineering, Inc.

Sensor shield wire  

(if equipped) should be 

grounded at one end only

Sensor shield wire  

(if equipped) should be 

grounded at one end only

No Sense Leads

Jumper 6 to 12 ONLY if 

sense leads are NOT used

6

5

7

8

10

9

11 12

Strain 

Gauge

V

0

 

+

V

0

 –

V

EX

 –

V

EX

 

+

Exc 

+

Exc –

Sig 

Sig 

+

Sig 

+

Exc –

Sig –

Exc 

+

Test Cal.

Span

Zero

Test

Output

Input

DMD4059

Strain Gauge to DC

Isolated Transmitter

LED

Excitation

LED

OMEGA Engineering, Inc.

1

 2 3 4

5  6 

7  8

9 10 11 12

13 14 

15 

16

Input

Cal. and Sense

Output

Power

To avoid damage 

to the module, 

do not make any 

connections to 

unused terminals

Wire terminal 
torque 
0.5 to 0.6 Nm or 
4.4 to 5.3 in-lbs

Excitation Voltage Trim
Variable Brightness Output Indicator

Output Test Level Adjust

Push to Test Output
Output Span Calibration

Variable Brightness Input Indicator
Output Zero Calibration

Summary of Contents for DMD4059

Page 1: ...ncrements Maximum Output 10 VDC maximum at 120 mA Drive Capability Up to four 350 Ω bridges at 10 VDC Fine Adjustment 5 via multi turn potentiometer Stability 0 01 per C Sense Lead Compensation Better than 0 01 per 1 Ω change in leadwire resistance Maximum leadwire resistance 10 Ω with 350 Ω at 10 VDC LoopTracker Variable brightness LEDs for input output loop level and status DC Output Ranges Volt...

Page 2: ...000V 008V 001V 006V 009V 002V 007V 003V 004V 005V 000I 008I 001I 006I 009I 002I 007I 003I 0 100 mV 800V 808V 801V 806V 809V 802V 807V 803V 804V 805V 800I 808I 801I 806I 809I 802I 807I 803I 0 120 mV F00V F08V F01V F06V F09V F02V F07V F03V F04V F05V F00I F08I F01I F06I F09I F02I F07I F03I 0 200 mV 100V 108V 101V 106V 109V 102V 107V 103V 104V 105V 100I 108I 101I 106I 109I 102I 107I 103I 0 250 mV 400V...

Page 3: ...tputs 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 Diagnostic Voltage Measurements Using a meter with at least 10 megaohm input impedance measure the voltage coming from the strain gauge at the locations shown Sensitivity is measured in mV V Positive Meter Lead Negative Meter Lead Meter Reading...

Page 4: ...by OMEGA if the unit is found to be defective it will be repaired or replaced at no charge OMEGA s WARRANTY does not apply to defects resulting from any action of the purchaser including but not limited to mishandling improper interfacing operation outside of design limits improper repair or unauthorized modification This WARRANTY is VOID if the unit shows evidence of having been tampered with or ...

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