User Manual

Rockwell Automation Publication 1756-UM005B-EN-P - January 2013 35
Module Features Chapter 3
Understand Module
Resolution, Scaling
and Data Format
The following three concepts are closely related and must be explained in
conjunction with each other:
• Module Resolution
• Scaling
Module Resolution
Resolution is the smallest amount of change that the module can detect.
High-speed analog I/O modules are capable of 14-bit resolution. The 14 bits
represent 16,384 counts. Depending on the operating range, the available counts
varies, as shown in Figure 4
.
Figure 4 - Available Counts
IMPORTANT
A module’s resolution is fixed. It does not change regardless of how you decide
to scale your module.
4096 Counts
-10V 0V 5V 10V
8192 Counts
16,384 Counts
0 mA 21 mA
8192 Counts
Voltage Resolution
Current Resolution
0…5V (actual limit = 5.25V)
Inputs Only
0…10V (actual limit = 10.5V)
Inputs Only
-10…10V (actual limit = -10.5V …10.5V)
Inputs and Outputs
0…21 mA
Outputs use 8192 counts of
current resolution.
4096 Counts
0 mA 21 mA
0 to 21 mA
Inputs use 4096 counts of
current resolution.