Allen-Bradley 1756-IF16IH ControlLogix Analog Input Module

Configured for high-density current signal acquisition in ControlLogix platforms, the Allen-Bradley 1756-IF16IH (1756-IF16IH Analog Input Module) provides direct physical execution of isolated measurement with integrated HART protocol support. The module features 16 isolated current input channels, each equipped with an independent HART modem to facilitate digital communication with field instrumentation. It supports standard current ranges of 0-20 mA and 4-20 mA, utilizing differential inputs to reject common-mode noise. The design ensures protocol-transparent data tunneling, allowing for the simultaneous transmission of analog process variables and digital diagnostic information from HART-enabled field devices directly into the ControlLogix backplane.

Hardware Specifications

4-20 mA HART Loop Protocol and Connectivity

The 1756-IF16IH integrates dedicated HART modems per channel, enabling the module to perform frequency shift keying (FSK) modulation required for HART communication on top of the 4-20 mA analog signal. This architecture allows the module to extract device-specific configuration and diagnostic data from field transmitters without requiring external multiplexers. The system maintains high-integrity signal conversion by implementing robust filtering, which suppresses industrial electromagnetic interference while preserving the integrity of the HART digital overlays. Users can access these digital variables through the ControlLogix tag structure, allowing for integrated device management within the primary control logic.

Frequently Asked Questions (FAQ)

Q: Can this module perform HART communication on all 16 channels simultaneously?

A: Yes, the 1756-IF16IH features an independent HART modem on each of its 16 isolated channels, supporting concurrent digital communication across all inputs without multiplexing.

Q: Is this module compatible with standard 1756-TBCH or 1756-TBS6H terminal blocks?

A: The module is designed for use with compatible 1756 ControlLogix terminal blocks that provide the necessary wiring termination points for 16-channel analog signals and their respective cable shields.

Field Installation Guidelines

1. Install the module into a compatible ControlLogix chassis slot. Ensure the chassis is properly grounded to the cabinet earth bus to minimize noise coupling into the analog inputs.
2. Use shielded twisted-pair cabling for all input signal runs. Terminate the cable shields at the designated grounding bar on the terminal block to maintain common-mode noise rejection.
3. Verify that the HART-enabled field devices are properly loop-powered or configured to draw current within the 0-20 mA range supported by the module.
4. Configure the module in the ControlLogix programming environment by selecting the appropriate HART-enabled input profile to ensure the software correctly maps the digital variables to the controller tags.
5. Inspect all terminal block connections for mechanical security and ensure that the keying mechanism matches the module slot to prevent improper insertion.