Model DT333-0700
4-Wire mV/TC Dual Transmitter w/USB
Acromag, Inc. Tel: 248-295-0880
- 26 -
http://www.acromag.com
- 26 -
https://www.acromag.com
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 sensor at input
1 and earth ground at a
connected Personal
Computer’s USB port.
Without USB isolation, a ground loop is
possible between a grounded input signal
and earth ground of the PC USB port. The
input return of this model is normally biased
to 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 to
a PC. 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.
USB has not enumerated the
device.
Use the reset button of the Acromag USB
isolator to trigger re-numeration of the
transmitter, or simply unplug and re-plug the
USB cable to the transmitter.
Communication or power was
interrupted with USB
connected while configuration
software was running.
Close the current connection with the
software, then select and re-open the
transmitter for communication (or simply exit
the Configuration software and reboot it).
For an input step, the
output appears to make 2 steps to reach its final value…
For a step change in the input,
the A/D needs two input
samples to ramp-up to its final
level.
When you step the input signal, it takes two
samples for the A/D to ramp up to its final
output level, and this is evident when using a
scope to examine the output transition in
response to a step change at the input, which
appears to make two steps in its transition to
its final level.
