Rockwell Automation 1756-OF8I ControlLogix Eight-channel Isolated Analog I/O Modules - Manual (Page 47)

Rockwell Automation Publication 1756-UM540A-EN-P - May 2014 47
1756-IF8I Isolated Analog Input Module Chapter 3
Power Calculations with the 1756-IF8I Module
The module’s 24V backplane current requirements increase when it operates with
a Current input type and Source Loop Current mode enabled.
The 1756-IF8I module uses the power provided across the ControlLogix chassis
backplane as the source for loop power. Because of the demands placed on that
supply, that is, the 1756-IF8I module consumes 10.6 W of backplane power, take
special care when calculating the power requirements for modules in the same
chassis as a 1756-IF8I module.
For example, when used with the 1756-L75 controller and operating in the
Sourcing Loop Current mode, you can place only six 1756-IF8I modules in the
chassis before exceeding the wattage capacity of the power supply.
Other Devices in the Wiring Loop
The voltage source on each channel can drive loop impedance of up to
approximately 1300 Ω. This lets you include other devices, such as chart
recorders and meters, in the current loop.
For more information on wiring the 1756-IF8I module, see page 61 .
Multiple Input Ranges
The 1756-IF8I module offers multiple input ranges that are dictated by channel
configuration choices. The input type selection determines the available ranges.
To see where to select the input range, see page 127 .
Input Type Input Range
Current (mA) 0…20 mA
Voltage (V) Any of the following:
• -10…10V
• 0…5V
• 0…10V