The Allen-Bradley 1756-IF8I, also cataloged as the 1756-IF8I Analog Input Module, operates as a dedicated hardware component for high-resolution analog signal acquisition within ControlLogix system platforms.

Module Variant Identification

• Catalog Part Number: 1756-IF8I
• Series Architecture: ControlLogix
• Hardware Function: Isolated 8-Channel Analog Voltage/Current Input
• Tariff Classification Code: 8537101190

Operational Specifications

Backplane Integration & Deterministic Network Execution

The 1756-IF8I utilizes an internal Sigma-Delta converter to execute analog-to-digital signal conversions with 16 to 21 bits of resolution across high-density channel configurations. Channel-to-channel galvanic isolation prevents ground loop interference across individual loops. Configured inside the standard ControlLogix chassis backplane, the module maintains firmware flash compatibility and supports high backplane bus communication velocity across EtherNet/IP deterministic networks, delivering stable real-time process variable data directly to the controller without signal crosstalk.

Kit Contents & Packaging

• 1 x 1756-IF8I Analog Input Module
• 1 x Factory Product Documentation insert

Field Installation Instructions

• Verify chassis power is off or adhere to hot-swap safety protocols prior to insertion.
• Align the module housing with the top and bottom chassis guide rails of the target slot.
• Slide the unit inward until the top and bottom locking latches fully secure into the backplane.
• Wire field instrumentation signals to the corresponding Removable Terminal Block (RTB) using shielded twisted-pair cabling.
• Connect cable drain wires to the designated chassis ground bus to prevent EMI corruption.

Technical Clarifications

• Does the 1756-IF8I support mixed voltage and current inputs simultaneously?

  Yes. Each of the 8 isolated channels can be independently configured in software for voltage (-10 to 10 V, 0 to 10 V, 0 to 5 V) or current (0 to 20 mA) operating modes.

• What conversion methodology does this module utilize for analog measurements?

  The module utilizes an onboard Sigma-Delta conversion method to achieve selectable measurement resolution ranging between 16 bits and 21 bits.

• How much backplane current does the 1756-IF8I draw at 5.1 VDC?

  The module draws exactly 200 mA from the 5.1 VDC ControlLogix chassis backplane bus rail.

• What are the 24 VDC power requirement options for this input card?

  Depending on operating conditions and loop power loading, current draw on the 24 VDC backplane supply is rated at either 150 mA or 400 mA.

• Does each channel require a separate ground isolation path?

  Yes. The 8 input channels are individually isolated, preventing common-mode voltage differences between loops from degrading input measurement accuracy.

• What is the mechanical enclosure rating for the 1756-IF8I module?

  The module features an open-style enclosure design intended for direct installation inside a protective industrial control cabinet or NEMA-rated panel.

• What type of field connector attaches to the front of the 1756-IF8I?

  The module connects to field wiring using a compatible 1756 ControlLogix Removable Terminal Block (RTB), such as the 1756-TBCH or 1756-TBS6H.

• Are the channel ranges user-selectable in Studio 5000 logix designer software?

  Yes. Each channel range (-10 to 10 V, 0 to 10 V, 0 to 5 V, or 0 to 20 mA) is software-configurable within the module properties dialog.