Model TT231-0600
Two-Wire RTD Transmitter w/USB
Acromag, Inc. Tel: 248-295-0880
- 31 - http://www.acromag.com
- 31 -
http://www.acromag.com
Diagnostics Table…
POSSIBLE CAUSE
POSSIBLE FIX
Cannot Communicate with Transmitter via USB…
Loop power ON to the unit?
Unit requires a loop power connection, even
when connected to USB. The loop power
supply should also be present before
connecting to USB.
Output goes 1mA above the selected Over-Range Value (ORV)…
This is the Upscale alarm level
and indicates the input signal
exceeds the common mode
range of the input. This can also
occur if the third sensor wire is
missing (3/4-wire RTD), a lead
has broken, the sensor has
burned out or is open, or the
jumper between terminals 3 & 4
of the transmitter is not installed
(2-wire RTD).
An Upscale alarm is normally driven by a
sensor fault (open sensor or broken lead)
with lead break detection set upscale. It can
also be triggered by a very high sensor
resistance that looks open to the transmitter.
Check sensor resistance, sensor connections,
and your connection to input terminal 4, to
restore input operation. You can check your
sensor connections by measuring a voltage
drop across your input resistance equal to
~0.5mA* Sense_Ohms? If connections are
OK and you measure a voltage drop across
the sensor, then sensor value is likely out of
range, or unit has been miscalibrated.
Output goes ~0.4mA below selected Under-Range Value (URV)…
This is the Down-scale alarm
level and indicates the input
signal exceeds the common
mode range of the input. This
can also occur if the third sensor
wire is missing (3/4-wire RTD), a
lead has broken, the sensor has
burned out or open, or the
jumper between terminals 3 & 4
of the transmitter is not installed
(2-wire RTD).
A Downscale alarm level is driven by a sensor
fault (open sensor or broken lead) with lead
break detection set downscale. It can also be
triggered by a very high sensor resistance
that looks open to the transmitter. Check
sensor resistance, sensor connections, and
your connection to input terminal 4, to
restore input operation. You can check your
sensor connections by measuring a voltage
drop across your input resistance equal to
~0.5mA* Sensor_Ohms? If connections are
OK and you measure a voltage drop across
the sensor, than your sensor value is likely
out of range, or the unit has been
miscalibrated.
Output goes 0.4mA below the lowest possible Under-Range Value…
An output level 0.4mA below the
lowest URV setting can be
indicative of a checksum error
encountered in a data exchange
with the internal EEPROM
memory. This assumes that you
have not configured an Under-
Range Value to its lowest
setting.
This is a rare error that is not likely to occur,
but if persistent, it may indicate a unit defect.
You can reset the transmitter, or simply cycle
power to clear it. If it continues to occur,
then you should try restoring factory
calibration. If the error still occurs, you
should consult with the factory and arrange
for the unit to be returned for repair or
replacement.