Rockwell Automation 1746-INT4 Thermocouple/MV Isolated/ User Manual - Manual (Page 111)

Publication 1746-UM614B-EN-P - September 2007
Glossary 111
input data scaling
Depends on the data format that you select for the channel data word.
You can select from scaled-for-PID or Engineering Units for millivolt,
thermocouple, or CJC inputs, which are automatically scaled. You may
also select proportional counts, which you must compute to fit your
application’s temperature or voltage resolution.
local system
A control system with I/O chassis within several feet of the processor,
and using 1746-C7 or 1746-C9 ribbon cable for communication.
LSB (least significant bit)
The bit that represents the smallest value within a string of bits. Refers
to a data increment defined as the full scale range divided by the
resolution.
multiplexer
A switching system that allows several input 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 electrical
noise between differential inputs, but not between an input and
ground or ground reference.
remote system
A control system where the chassis can be located several thousand
feet from the processor chassis. Chassis communication is via the
1747-SN Scanner and 1747-ASB Remote I/O Adapter.
resolution
The smallest detectable change in a measurement, typically expressed
in engineering units (for example 0.15 °C) or as a number of bits. For
example, a 12-bit value has 4,096 possible counts. It can therefore be
used to measure 1 part in 4096.
sampling time
The time for an A/D converter to sample an input channel.