Acromag DT236-0600, User Manual, Page: 27 / 40

Model DT23x-0600 Dual Two-Wire DC I/V Input Transmitters
Acromag, Inc. Tel: 248-295-0880 - 27 -
http://www.acromag.com
- 27 - https://www.acromag.com
Diagnostics Table …
POSSIBLE CAUSE POSSIBLE FIX
Cannot Calibrate Input Channel…
Are inputs wired properly? Check that input is wired to correct ± input
terminals using the correct polarity for your
model. Note these models have two input
paths A or B that differ by their supported
nominal range.
Are you wired to the correct input
terminals for your desired range? TB1 and TB3 support multiple input ranges
(refer to specifications).
Cannot Calibrate the Output or Cannot Test the Unit…
Loop power ON in the units
output circuit? The unit receives power from both USB
(when connected), and the output loop
power supplies. While you can configure a
unit over USB without loop power applied, a
loop 1 power connection is required to test
operation or calibrate the unit.
Unit drives a low current, but fails to drive higher output current...
Loop supply voltage is too low to
support current into the loop load
or the loop load resistance is too
large for the current level. Does
the output fault LED blink at the
higher current? Check power voltage level. Make sure it is
at least 7V plus 0.02x*Rload. If transmit
distance is especially long, then it must have
added voltage to support the IR drop in the
wire. Ideally, the voltage should also have
ample overhead to drive the load at the
maximum upscale output current > 20mA.
Cannot Measure Input Voltage or Input Current…
Your input may be wired to the
wrong terminal. These models
have two isolated input channels,
each with two input paths A or B
that differ by their supported
nominal range. For example, on the DT236, DC Current is
input to path A TB1/TB3-1 (leftmost
terminal), while ±0.5V DC is input to
TB1/TB3-3 path B (rightmost terminal). For
the DT237, only DC voltages up to ±1V
connect to path A TB1/TB3-1. If you
mistakenly wire these lower voltage signals
to path B at TB1/TB3-3, your resolution will
be poor as TB1/TB3-3 has a 12.52:1 divider
at its input to support a larger signal span.
Likewise, if you connect ±10V or ±5V to the
DT237 path A at TB1/TB3-1/, you would
drive it into over/under-range.
For input step, output appears to make 2 steps to reach its final value…
For a step change at an input
channel, the channel A/D typically
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
value, 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 to arrive
at its final level.