Range Selection
See white model/serial number label for module power require-
ments, and any applicable options or custom ranges. It is gener-
ally easier to select ranges before wiring and installation.
See table on next page for module range settings. From the
table, find the rotary switch setting that matches your input and
output range.
For most applications 0-100% of the potentiometer range is
used. The DMD4008 can be set up to use part of the potenti-
ometer range.
Input switch B controls the percent of the potentiometer range
to use.
Input switch C controls the percent of the range offset from zero.
Make sure to set the V—I switch for voltage or current output
respectively.
Electrical Connections
WARNING! All wiring must be performed by a qualified electri-
cian or instrumentation engineer. See diagrams for terminal
designations and wiring examples.
WARNING! Avoid shock hazards! Turn signal input, output, and
power off before connecting or disconnecting wiring, or remov-
ing or installing module.
Module Power Terminals
Check white model/serial number label for module operating
voltage to make sure it matches available power.
When using DC power, either polarity is acceptable, but for
consistency with similar products, positive (+) can be wired to
terminal 13 and negative (–) can be wired to terminal 16.
Signal Input Terminals
The potentiometer must be connected to all three signal input
terminals as shown. The DMD4008 utilizes a stable 1 VDC
source to excite the potentiometer.
Signal Output Terminals
Polarity must be observed for output wiring connections. If the
output does not function, check switch settings and wiring
polarity.
If your device requires a current input, determine if it provides
power to the current loop or if it must be powered by the module.
Use a multi-meter to check for voltage at the input terminals of
your device. Typical voltage may be in the range of 9 to 24 VDC.
In this case, wire the device to module terminals 2 and 3.
Mounting to a DIN Rail
The housing is IP40 rated and requires vertical installation on
a 35 mm DIN rail in a protective panel or enclosure away from
heat sources.
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.
Calibration
Front-mounted Zero and Span potentiometers are used to
calibrate the output to compensate for load and lead variations.
Note: Perform the following calibration procedure any time
switch settings are changed.
1. Apply power to the module and allow a minimum 20 minute
warm up time.
2. Set the input potentiometer to its minimum value to provide
an input to the module equal to the minimum input required
for the application.
3. Connect an accurate measurement device to the module
output. Adjust the module’s Zero potentiometer for the exact
minimum output desired. The Zero control should only be
adjusted when the input signal is at its minimum to produce
the corresponding minimum output signal. Example: for a
4-20 mA output signal, the Zero control will allow adjustment
of the 4 mA or low end of the signal.
4. Set the input potentiometer at its maximum, and then
adjust the module’s 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 cor-
responding maximum output signal. Example: for 4-20 mA
output signal, the Span control will provide adjustment for
the 20 mA or high end of the signal.
5. Repeat adjustments for maximum accuracy.
Output Test Function
The output test potentiometer is factory set to provide approxi-
mately 50% output. When the test button is depressed it will
drive the output side of the loop 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.
potentiometer for the desired output level.
Operation
The DMD4008 utilizes a stable 1 VDC source to excite the
potentiometer. This voltage is stabilized against the potentiom-
eter resistance value variations over the entire operating range.
The resulting potentiometer wiper voltage is amplified and
passed through an optical coupler to the output stage where it is
scaled to the desired output range.
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.
DMD4008, DMD4008-DC Potentiometer to DC Isolated Conditioners
2
Potentiometer Input
Terminal
Full scale or high side of potentiometer
9
(
+1 VDC)
Zero or low end of potentiometer
10 (–)
Potentiometer wiper arm
11
Type of Device for Output
– Terminal + Terminal
Measuring/recording device
accepts a voltage input.
3 (
–)
4
(
+)
switch E
set to “V”
Measuring/recording device
accepts a mA (current) input and
is unpowered or passive. Module
provides the loop power.
3 (
–)
4
(+20 V)
switch E
set to “I”
Measuring/recording device
accepts a mA (current) input
and provides power to the cur-
rent loop.
2 (
–)
3
(
+)
switch E
set to “I”
Spring Clip
Upper Mount
Lower Mount
6
5
7
8
13 Power AC or DC +
14
Earth Ground
16 Power AC or DC –
14
13
15
16
10
9
11
12
9 Full Scale
11 Wiper Arm
10 Minimum
Potentiometer
2
1
3
4
Voltage Output
–
+
+
–
Voltage
Device
2
1
3
4
–
+
Powered
4-20 mA
Device
Current Sinking Output
switch
E
set to “I”
External device provides
loop power
Current Sinking Output
switch E set to “I”
External loop supply
2
1
3
4
–
+
+
–
Loop
Power
Source
+
–
4-20 mA
Device
R
i
Cu 60/75°C
conductors
14 AWG
max.
To maintain full isolation
and avoid malfunctions,
do not connect power
supplies in common
with input, output or unit
power.
Do not connect anything
to unused terminals.
2
1
3
4
Current Sourcing Output
Set switch
E
to “I”
Passive
Current
Device
+20 V
–
+
Not used
1
2 3 4
5 6 7 8
9 10 11
12
13 14
15
16
Input
Not used
Output
Power
Do not connect
anything to
unused terminals
