Model DT33x-0700
4-Wire DC I/V Dual Transmitter w/USB
Acromag, Inc. Tel: 248-295-0880
- 26 -
http://www.acromag.com
- 26 -
https://www.acromag.com
How it Works...
Input 1 and USB, Input 2, each output, and the power circuits are all isolated from
each other. This unit does not draw power from USB, but the USB port ground is
common to the input 1
circuit ground. The USB port ground of most PC’s is also
common to the USB cable shield and earth ground. Input 1 sensors could be
grounded or ungrounded. For this reason, it is recommended that USB signals be
isolated when connected to a PC to prevent a ground loop from occurring between
the PC earth ground and a grounded input 1 sensor, which would have the negative
effect of pulling the input bias supply to ground and clipping any negative range.
TROUBLESHOOTING
Diagnostics Table
Before attempting repair or
replacement, be sure that all
installation and configuration
procedures have been followed
and that the unit channels are
wired properly. Verify that power
is applied to the unit and that your
supply voltage is at least 6V. Verify
that your loads are appropriate to
your output type and wired to the
correct terminal, current or
voltage. Check both channels.
If your problem still exists after
checking your I/O channel wiring
and reviewing this information, or
if other evidence points to another
problem with the unit, an effective
and convenient fault diagnosis
method is to exchange the
questionable unit with a known
good unit.
Acromag’s Application Engineers
can provide further technical
assistance if required. Repair
services are also available from
Acromag.
POSSIBLE CAUSE
POSSIBLE FIX
Cannot Communicate with Unit
via USB…
Output shifts off-
range when you connect USB…
Output Erratic, Not operational, or at Wrong Value…
Unit fails to operate or exhibits an
output shift…
A missing USB Isolator could
cause a ground loop between a
grounded input 1 sensor and
earth ground at the connected
Personal Computer’s USB port
because USB and input 1 share
a common ground connection.
Without USB isolation, a ground loop is
possible between a grounded input and earth
ground of the PC USB port. The input to this
model is normally biased up 1.25V off input
ground to process negative-going signals. A
grounded signal source could inadvertently
short this bias to earth ground and clip the
negative input range with a non-isolated USB
connection. For this reason and for increased
safety and noise immunity, it is best to
connect to USB via a USB isolator. Use an
isolator like the Acromag USB-ISOLATOR.
Otherwise, use a battery powered laptop to
configure the transmitter, which does not
normally earth ground its USB port.
Software Fails to Detect Transmitter…
Bad USB Connection
Recheck USB Cable Connection.
(Agility) Your smart device
needs permission to connect to
the Acromag transmitter the
first time.
When you first connect to your smart device,
it will prompt for permission. Be sure to give
your permission or Agility will not discern
your device connection. You may have to
unplug/replug the USB connection to your
tablet/phone to get this prompt.
USB has not enumerated the
device.
Use the reset button on the Acromag USB
isolator to trigger renumeration of the unit,
or simply unplug and re-plug the USB cable to
the transmitter.
