Rockwell Automation 1769-IT6 Compact I/O 1769-IT6 Thermocouple/mV Input Module - Manual (Page 159)

Rockwell Automation Publication 1769-UM004B-EN-P - March 2010 159
Glossary
module update time The time required for the module to sample and convert the input signals of all
enabled input channels and make the resulting data values available to the
processor.
multiplexer An switching system that allows several signals to share a common A/D
converter.
normal mode rejection (differential mode rejection) A logarithmic measure, in dB, of a device’s ability to
reject noise signals between or among circuit signal conductors.
The measurement does not apply to noise signals between the equipment
grounding conductor or signal reference structure and the signal conductors.
number of significant bits The power of two that represents the total number of completely different digital
codes to which an analog signal can be converted or from which it can be
generated.
overall accuracy The worst-case deviation of the digital representation of the input signal from the
ideal over the full input range is the overall accuracy. Overall accuracy is expressed
in percent of full scale.
repeatability The closeness of agreement among repeated measurements of the same variable
under the same conditions.
resolution The increment of change represented by one unit. For example, the resolution of
engineering units x1 is 0.1° and the resolution of raw/proportional data is equal
to (maximum_value - minimum_value)/65534.
sampling time The time required by the A/D converter to sample an input channel.
status word Contains status information about the channel’s current configuration and
operational state. You can use this information in your ladder program to
determine whether the channel data word is valid.
step response time The time required for the channel data word signal to reach a specified
percentage of its expected final value, given a full-scale step change in the input
signal.
thermocouple A temperature sensing device consisting of a pair of dissimilar conductors welded
or fused together at one end to form a measuring junction. The free ends are
available for connection to the reference (cold) junction. A temperature
difference between the junctions must exist for the device to function.
update time See ‘module update time’.