Model TT231-0600
Two-Wire RTD Transmitter w/USB
Acromag, Inc. Tel: 248-295-0880
- 30 - http://www.acromag.com
- 30 -
http://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 voltage is sufficient to
supply over-scale current into the
load (MIN 0.020*Rload), plus 9V 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 Fails to Scan Transmitter…
Bad USB Connection
Recheck USB Cable Connection
Loop power was enabled after
connecting to USB.
You must enable the loop power supply
before connecting to USB. With loop power
present, disconnect then reconnect the USB
cable to the transmitter.
USB has not enumerated the
device.
Use the reset button on the Acromag USB
isolator to trigger renumeration of the
transmitter, or simply unplug/replug the USB
cable to the transmitter.
Communication or power was
interrupted while USB was
connected and the configuration
software was running.
Close the current connection with the
software, re-scan the transmitter, then select
and re-open the transmitter for
communication (or simply exit the
configuration software and reboot it).
Output Erratic, Not operational, or at Wrong Value…
Missing USB isolation
If your two-wire output loop is grounded,
then connecting USB to the transmitter will
drive a ground loop between your current
loop and earth ground at the PC. Always use
USB signal isolation, or alternatively, you can
connect directly to a battery-powered
laptop, which does not earth ground its USB
connection.
Otherwise…
Verify loop power and voltage level. Try
Closing the connection and re-opening it.
Output goes to Over-Range Value (ORV) or Under-Range Value (URV)…
This indicates that the input
signal is out of range. If the level
is 1mA above the ORV or 0.4mA
below URV, then this would
indicate a sensor fault or lead
break.
Check your input signal with respect to your
calibrated range and reduce or increase it as
required to drive your output current within
its linear operating range. Also check the
wiring of your input sensor.
Cannot Communicate with Transmitter via USB…
A missing USB Isolator could
cause a ground loop when
connecting to USB from a
Personal Computer.
A ground loop is created between a normally
grounded two-wire current loop and earth
ground of the PC USB port. Only connect to
USB via a USB isolator. Otherwise, use a
battery powered laptop to configure the
transmitter.