Technical Specifications
| Parameter Name | Parameter Value |
|---|---|
| Product Model | 1756-IF4FXOF2F (Revision /A, firmware 1.x) |
| Manufacturer | Rockwell Automation / Allen-Bradley |
| Product Type | ControlLogix High-Speed Analog Combination I/O Module |
| Inputs | 4 high-speed, sub-millisecond, differential |
| Input Ranges | ±10 V, 0…10 V, 0…5 V, 0…20 mA |
| Input Resolution | ~14 bits across ±10.5 V (1.3 mV/bit); ~12 bits across 21 mA (5.25 µA/bit) |
| Outputs | 2 high-speed voltage or current |
| Output Ranges | ±10 V, 0…20 mA |
| Output Resolution | 14 bits (1.3 mV/bit) voltage; 13 bits (2.8 µA/bit) current |
| Module Scan Time | 400 µs min (Rev /A, fw 1.x); 300 µs min (Rev /B, fw 3.x) |
| Output Settling Time | < 2 ms to 95% of final value (resistive loads) |
| Output Drive Capability | Voltage: >2000 Ω; Current: 0…750 Ω |
| Calibrated Accuracy @ 25 °C | 0.05% of range (after calibration); <0.1% across interval |
| Calibration Interval | 12 months |
| Conversion Method | Inputs: Successive Approximation; Outputs: R-Ladder DAC |
| Backplane Current Draw | 375 mA @ 5.1 V; 100 mA @ 24 V |
| Total Backplane Power | 4.3 W (voltage mode); 4.7 W (current mode) |
| Isolation Voltage | 250 V continuous, basic insulation, I/O to backplane |
| Overvoltage Protection | 30 V DC (voltage inputs); 8 V AC/DC (current inputs) |
| Removable Terminal Block | 1756-TBCH or 1756-TBS6H (36-pin), ordered separately |
| Slot Width | 1 |
| Wire Category | 2 |
| Operating Temperature | 0…60 °C (32…140 °F) |
| Nonoperating Temperature | −40…85 °C (−40…185 °F) |
| Relative Humidity | 5…95% noncondensing |
| Vibration / Shock | 2 g @ 10…500 Hz; 30 g operating, 50 g nonoperating |
| Temperature Code | T4A (North America), T4 (IEC) |
| Certifications | UL (File E65584), CSA (LR54689C, LR69960C Class I Div 2), CE, C-Tick, ATEX Ex nA IIC T4 X Gc, FM Class I Div 2 Groups A–D, KC |
Main Features and Advantages
Sub-millisecond scan time for demanding loop dynamics. The ALLEN-BRADLEY 1756-IF4FXOF2F was designed specifically for applications in which standard ControlLogix analog cards are too slow. Revision /A hardware running firmware 1.x delivers a minimum module scan time of 400 µs, while Revision /B with firmware 3.x improves this to 300 µs — allowing fast-rising analog events such as hydraulic pressure transients, torsional vibration, or servo-feedback ripple to be captured without aliasing. Inputs use a successive-approximation converter that resolves each channel with approximately 14 bits across the ±10.5 V span, and repeatability is held to ±1 LSB so that a steady-state input produces a stable, repeatable digital valueelit.ee.
Mixed voltage and current architecture in one module. Each of the four input channels on the 1756-IF4FXOF2F is independently software-configurable for ±10 V, 0…10 V, 0…5 V, or 0…20 mA operation, and the two output channels can likewise be set independently to ±10 V or 0…20 mA. This mixed-signal flexibility allows a single module to interface 2-wire transmitters, 3-wire potentiometer feedback, chart recorders, I/P converters, and servo valve drivers simultaneously, eliminating the need to combine separate input-only and output-only cards in the same chassis — a genuine slot-saving benefit in densely populated ControlLogix racks.
High-accuracy, field-calibratable performance. Every ALLEN-BRADLEY 1756-IF4FXOF2F ships factory-calibrated to 0.05% of range and supports in-place recalibration through Studio 5000 Logix Designer at a 12-month interval, with a CAL button on the front panel for entering calibration mode. Gain drift is held to 25 ppm/°C on voltage ranges and 35 ppm/°C on current inputs, while output offset drift is 50 µV/°C (voltage) and 1 µA/°C (current) — accuracy that holds up in temperature-cycling industrial environments without frequent intervention.
Robust signal protection and diagnostics. Voltage inputs on the 1756-IF4FXOF2F tolerate up to 30 V DC without damage, and current inputs tolerate 8 V AC/DC, while open-circuit detection drives the channel to positive full-scale within 1 second so that a broken 2-wire transmitter loop is immediately apparent in the controller logic. Output channels are electronically current-limited to 21 mA or less for short-circuit protection, and the front-panel OK and CAL status LEDs provide at-a-glance module health during walk-downselit.ee.
Producer-Consumer integration with the ControlLogix backplane. As a native ControlLogix module, the 1756-IF4FXOF2F participates fully in Rockwell’s Producer-Consumer architecture, broadcasting input data and consuming output data at a minimum 1 ms RPI so that multiple controllers, HMI stations, and safety controllers on the same chassis can share the analog values simultaneously. Isolation is provided at 250 V continuous (basic insulation, I/O to backplane), and electronic keying prevents accidental installation of the wrong module type in a configured slotelit.ee.
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