The 1756-IF8 is a high-performance analog input module for the Allen-Bradley ControlLogix platform, occupying one chassis slot and communicating with 1756 controllers over the backplane. It provides 8 configurable input channels that can be wired as 8 single-ended, 4 differential, or 2 high-speed differential channels, allowing flexibility in wiring and noise immunity.
Each channel supports multiple input ranges, including ±10.25 V, 0–10.25 V, 0–5.125 V voltage inputs and 0–20.5 mA current inputs, using sigma-delta A/D conversion to achieve high accuracy and stability. Resolution is approximately 320 µV per count in the ±10.25 V range (15 bits plus sign), and up to 16 bits in the 0–10 V, 0–5 V, and 0–20 mA ranges, providing fine granularity for demanding process control applications. Data can be presented in integer (two’s complement, left-justified) or 32-bit IEEE floating-point format, simplifying scaling to engineering units in the controller.
The module offers extensive diagnostics and alarming, including underrange/overrange detection, open-circuit detection, short-circuit detection, process alarms, digital filtering, and rate-of-change alarms, enabling early detection of field issues and increased system reliability. It uses the ControlLogix producer/consumer model to publish data to controllers and can be used in both local and remote chassis, making it suitable for scalable architectures.
Backplane power consumption is typically 150 mA at 5.1 V DC and 40 mA at 24 V DC, with module power dissipation around 1.73 W in voltage mode and 2.33 W in current mode. Field wiring requires a 1756-TBCH or 1756-TBSH removable terminal block (RTB), and channels are non-isolated from each other (for channel-to-channel isolation, users can select the 1756-IF8I model instead).
Typical applications include connecting 4–20 mA transmitters, ±10 V signals from drives, servo controllers, and other process instruments into ControlLogix systems in industries such as process control, water/wastewater, manufacturing, and building automation.
