Channel Temperature; Connection Method - Spectrum Controls Micro800 2085-IR8-SC User Manual

3-22 Chapter 3: Configuring the Micro800 Expansion I/O 2085-IR8-SC Using CCW
User's Manual Pub. 0300321-01 Rev. A
�� is the gain:
(�������� ������ℎ ���������� − �������� ������ ����������)
�� =
(������������ ������ℎ ���������� − ������������ ������ ����������)
The User High/Low Limit value is based on the selected Input Type and
the selected Data Format. The Actual High/Low Limit value used is the
actual limit of the selected Input Type without scaling. For example, if Pt
385 type and EU×1 are selected in the configuration table, the gain will
be 10 = (8500 - (-2000)) / (850 – (-200)), m = 10.
�� is the ADC signal data acquired at the terminal block and converted to
the corresponding Data Format.
If you have an RTD input, this �� is the actual temperature in degree C.
The firmware reads in the ADC data count. Next, the data count is
converted to the resistor value in ohms based on the gain setting of the
ADC and the setting of the 2-wire, or 3-wire; the resistor value is then
converted to temperature in degree C based on the RTD curve
specification.
�� is the offset: �������� ������ ���������� − (�� ∗ ������������ ������ ����������).
��ℎ���������� �������� is an offset in integer format.
The Channel Bias value is only applied to the raw measured value. It will
not be applied to shift the minimum and the maximum points and the
limits of the selected Input Type range. If the final channel input reading
is equal to or goes beyond the minimum or the maximum point of the
selected Input Type range, a Channel Fault and an Over/Under Range
Fault bits will be set in the input table.

3.6.4 Channel Temperature

The module provides a feature to select the temperature display unit for each
channel input reading if the channel is configured to use RTD measurement with
EU×1 or EU×10 Data Format used. Temperature is not used if the channel is
being used to run resistance measurements, or a non-engineering unit data format
is selected.
Index
0
1

3.6.5 Connection Method

The default option is used when the 3-wire RTD or resistance device is
connected. The module will run additional compensation to cancel out the lead-
wire resistance value. The next option provides more accurate measurement
when the connected RTD or resistance device is a 4-wire type. The last option
can be used to measure the value across the main resistance load plus the doubled
lead-wire resistance value if the 2-wire RTD or resistance device is connected.
Index Connection Method
0 3-wire with Compensation
1 4-wire
Unit Note
ºC Default
ºF
Note
Default