Rockwell Automation 1756-XXXX ControlLogix Analog I/O Modules - Manual (Page 57)

Publication 1756-UM009C-EN-P - December 2010 57
Non-isolated Analog Voltage/Current Input Modules (1756-IF16, 1756-IF8) Chapter 4
Differential Wiring Method
The differential wiring method is recommended for applications that may have
separate signal pairs or a common ground is not available. Differential wiring is
recommended for environments where improved noise immunity is needed.
In differential mode, the channels are not totally isolated from each other. If
multiple differential input signals have different voltage common references,
one channel could affect the reading of another channel. If this condition
cannot be avoided, then wire these inputs on different modules or replace the
non-isolated module with an isolated input module.
High-speed Mode Differential Wiring Method
You can configure the 1756-IF16 and 1756-IF8 modules for a high-speed
mode that will give you the fastest data updates possible. When using the
high-speed mode, remember these conditions:
• This mode uses the differential wiring method.
• This mode only allows use of one out of every four channels on the
module.
Update times for applications using the high-speed mode can be found on
page 60 .
IMPORTANT
This wiring method lets you use only half a module’s channels.
For example, you can use only eight channels on the
1756-IF16 module and four channels on the 1756-IF8 module.