Model DT23x-0600
Dual Two-Wire DC I/V Input Transmitters
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 is wired properly.
Verify that power is applied to the
loop and that your loop power
supply voltages are sufficient to
supply over-scale current into the
loads (up to 0.024*Rl
oad
), plus 7V
MIN at the unit terminals, plus any
line drop.
If your problem still exists after
checking your 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
Software Does Not Detect Unit or the Communication Set up
Screen is Blank…
USB is not connected between
unit and host PC.
Re-plug cable to verify USB cable from USB
isolator is plugged into the unit and the
isolator. Verify that USB cable from PC is also
plugged into the PC USB port and into the
isolator.
USB has not enumerated the
device.
Use the reset button on the Acromag USB
isolator to trigger renumeration of the
transmitter, or simply unplug and re-plug the
USB cable to the transmitter.
Communication or power was
interrupted with USB
connected and config software
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).
Cannot Communicate with Transmitter
via USB…
Unit fails to operate or
exhibits an output shift…
Output shifts off-
range when you connect USB…
A missing USB Isolator could
cause a ground loop between a
grounded input 1 signal/sensor
and earth ground at a
connected Personal Computer
via its USB port.
Isolated transmitters can be used with
grounded or ungrounded inputs and may
only connect to grounded input sensors if the
USB signals from the PC are also isolated.
Without USB isolation, a ground loop is
created between a grounded input and earth
ground of the PC USB port. Th
is module’s
input is biased 1.25V off input ground to
allow it to process negative-going signals.
Earth ground applied via the non-isolated
USB connection with an earth grounded
input 1 sensor would clip the input 1 bias and
truncate its negative signal range
. It’s best to
connect to USB via a USB isolator to protects
from this and to increase safety and noise
immunity. 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.
Output is
Erratic, Not operational, or at Wrong Value…
Is your output loop power
supply at the correct level for
your load?
Is Output Fault LED blinking?
Verify loop voltage and level in each output.
Ideally, your supplies must be adequate to
provide 7V MIN to the transmitter, plus the
IR drop in the loop load, plus the IR drop in
the lead wires, and all at the maximum loop
current (>20mA).