Model TT231-0600
Two-Wire RTD Transmitter w/USB
Acromag, Inc. Tel: 248-295-0880
- 19 - http://www.acromag.com
- 19 -
http://www.acromag.com
Configuration…
HELP
– You can press F1 for Help
on a selected or highlighted field
or control. You can also click the
[?] button in the upper-right hand
corner of the screen and click to
point to a field or control to get a
Help message pertaining to the
item you pointed to.
The actual operating range limits of your input sensor will depend on the linear
output operating range defined by the output under-scale and over-scale threshold
limit settings (set separately below). Threshold limiting allows you to define an
under-scale threshold, typically between 2.1mA and 3.6mA, and an over-scale
threshold between 21mA and 30mA. This indirectly corresponds to a linear
operating range outside of the input zero and full-scale limits. It also indirectly
defines the fault current levels which will be ~0.4mA below the under-scale
threshold for down-scale detection, and ~1.0mA above the over-scale threshold for
upscale detection. The Min/Max range of adjustment has already been calibrated
at the factory and the Min/Max values indicated will vary between units. Note that
the range of adjustment for the threshold levels can vary as much as ±10% of span
between units for the same “digital” setting.
Calibrate I/O Range Selection
CAUTION:
RTD Input levels
outside of the nominal input range
of the unit
(-50° to +850°C, or 0-900Ω) will not
be accepted for configuration of
zero or full-scale. Since not all
input levels can be validated
during field programming,
connecting or entering incorrect
signals will produce an undesired
output response.
IMPORTANT:
If you make any changes to the Configuration parameters, you must
re-calibrate your input.
Any changes to the Input Type, Sensor Wiring, Input
Zero/Full-Scale, or Output Zero/Full-Scale, are not written to the transmitter until
you complete the calibration sequence that is initiated by clicking the “Start
Calibration” button.
You can use the
“Get Config”
Calibration control button to read the current
configuration of the unit if you like, perhaps to determine the active configuration
prior to recalibrating it. Note that it will over-write the configuration parameter
selections of this screen that you may have just changed. It a good idea to always
check the current configuration selections to affirm your intentions before clicking
“Start Calibration”.
After making your input type and I/O range selections, you can click the
“Start
Calibration”
button of the Calibration section to begin calibrating your selections.
Calibration is a simple two step process (Resistance Input), or three step process (Pt
RTD Input), that adjusts the I/O range zero, the PGA gain and excitation, and
linearization (Pt RTD only). If you make a mistake and need to repeat a step, just
click “Abort Calibration” to restart from the beginning.
Calibration is an interactive process in which the software prompts you to apply
input signals and then measure the corresponding output current. First, it will
prompt you to apply the zero input signal resistance, then measure and record the
corresponding zero output signal current. Second, it does the same for the full-
scale input resistance and the corresponding full-scale output current signal (it
makes adjustments to gain at this stage, but with linearization turned off). Third for
Pt RTD input types, it enables linearization and prompts you to apply the full-scale
input resistance signal again and then measure and record the corresponding full-
scale output current (it uses this second full-scale measurement to adjust the
magnitude of its linearization correction for the sensor). There may still be
combinations of zero and full-scale that you will not be able to adjust and calibrate
the unit for. For example, this might occur for very tight input spans, or odd
endpoints. The Configuration Software will usually let you know when you need to
adjust your desired limits as you enter them.