Spectrum Controls 1769sc-HART Modules - Manual (Page 62)

Compact IO™ Isolated HART Analog Input Module
User's Manual 0300215-03 Rev. A
6-12
Reserved
Reserved for future expansion and should be set to zero.
Data Format
This selection allows the associated channel to present analog data in any of the
following formats:
•
Raw/Proportional Data
The value presented to the controller is proportional to the selected input and
scaled into the maximum data range allowed by the bit resolution of the A/D
converter and filter selected. The raw/proportional data format also provides the
best resolution of all the data formats.
If you select the raw/proportional data format for a channel, the data word will
be a number between -32767 and +32767. For example, if a 4 to 20 mA input
type is selected, 4 mA corresponds to -32767 counts and 20 mA corresponds to
+32767. See Determining
Effective
Resolution
and Range
.
NOTE: The raw/proportional counts, scaled-for-PID and percent of full-scale data
formats may yield the highest effective resolutions, but may also require that you
convert channel data to real engineering units in your control program.
•
Engineering Units
When using this data format, the module scales the input data to the actual
engineering values for the selected input type. Values are expressed with an
assumed decimal place. Refer to Table 6-8 (Data Formats).
The resolution of the engineering units data format is dependent on the range
selected and the filter selected. See Determining
Effective
Resolution
and Range.
•
Scaled-for-PID
The value presented to the controller is a signed integer with 0 representing the
lower input range and +16383 representing the upper input range.
To obtain the value, the module scales the input signal range to a 0 to +16383
range, which is standard to the PID algorithm for the MicroLogix 1500 and
other Allen-Bradley controllers (e.g. SLC). For example, if a 4 to 20 mA input
type is selected, 4 mA corresponds to 0 counts and 20 mA corresponds to
+16384 counts.
•
Percent Range
Input data is presented to the user as a percent of the specified range. The
module scales the input signal range to a 0 to +10000 range. For example, if a 4
to 20 mA input type is selected, 4 mA corresponds to 0 counts and 20 mA
corresponds to +10000 counts