Model DT335-0700
Dual RTD/Resistance Input Transmitter w/USB
Acromag, Inc. Tel: 248-295-0880
- 28 -
http://www.acromag.com
- 28 -
https://www.acromag.com
Diagnostics Table
…
POSSIBLE CAUSE
POSSIBLE FIX
Software Fails to Detect Transmitter…
Communication or power was
interrupted while USB was
connected and configuration
software running.
Close the current connection with the
software, then select & re-open the unit 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 2 input samples
to ramp up to its final level.
For an input step, it takes two samples for
the A/D to transition to its final output level,
evident when using a scope to examine the
output in response to a step change of the
input which will appear to make two steps in
its transition to its final level.
For Service & Repair:
This unit
contains solid-state components
and requires no maintenance,
except for periodic cleaning and
transmitter calibration (zero and
full-scale) and verification. Its
enclosure is not meant to be
opened for access and can be
damaged easily if snapped apart.
It is highly recommended that a
non-functioning transmitter be
returned to Acromag for repair or
replacement. Acromag has
automated test equipment that
thoroughly checks and calibrates
the performance of each
transmitter and can restore
firmware. Please refer to
Acromag’s Service
Policy and
Warranty Bulletins or contact
Acromag for complete details on
how to obtain repair or
replacement.
Output goes right to Over-Range (105%) or Under-
Range Limit…
This indicates that either the
input signal is out of range,
scaling is incorrect, or a sensor
lead has broken. It can also
occur due to contention
between earth ground at the PC
USB port and the input sensor.
Check and adjust the input signal as required
to drive output within its linear operating
range. A fully up/down-scale output can be
driven by a sensor fault, such as an
open/broken lead. Check input 1 sensor
wiring and if not isolating USB, check for a
ground loop between the sensor & USB port
earth ground.
Cannot Calibrate Input
Channel…
Is input wired properly?
Check that the input is wired to ± input
terminals using the correct polarity. Have
you added the input jumper(s) required for
3-wire or 2-wire input configuration.
Changing Input Filter Setting Affects Input
Calibration…
You may note a small shift in the
input reading when changing the
input filter setting.
An input should be calibrated at the desired
filter setting. For best results, set the input
filter as desired before calibrating the input.
Cannot Measure Input Temperature or Resistance
…
Have you wired the input to the
correct terminals for the input
type/range and configuration?
Refer to Sensor Input Connections and verify
the sensor or resistance decade box is wired
to the transmitter correctly.
Output Noise Seems Excessive
…
Scaled input or output range is
too small.
Scaling I/O to very small spans will diminish
resolution and signal to noise ratio,
potentially magnifying error. Every halving
of the nominal range reduces resolution by
1-bit. Increase your range span.
An orange output fault LED is ON...
Corresponding current output
load is too large to drive it
accurately, or you have an open-
circuit, or the output driver has
over-heated.
Indicates the current load is open-circuit or
too large to maintain its output accurately
(
≥525Ω), or the IC die temper
ature has
exceeded 142°C (resets upon cooling below
124°C). It may also occur if the loop supply
voltage is too low to support the load.