Product Overview
The Allen-Bradley 1746-FIO4V is a fast analog combination input/output module from the SLC 500 family (Bulletin 1746) — Rockwell Automation’s platform for small to mid-size machine and process control. The Allen-Bradley 1746-FIO4V consolidates four analog channels into a single 1746 chassis slot: two fast, differential analog input channels that are selectable by channel for voltage or current, and two grouped analog voltage output channels. This combination is deliberately aimed at the common machine-control problem of needing to read a process variable and simultaneously issue a modulating command — for example, reading a pressure or tension transducer while driving a proportional valve or variable-frequency drive — without dedicating two full-size analog cards to the task.
The input side of the Allen-Bradley 1746-FIO4V gives two differential channels, each configurable via an onboard DIP switch for either voltage or current. In current mode the nominal range is 0–20 mA (accommodating standard 4–20 mA instrumentation) with a 0–30 mA absolute maximum; in voltage mode the range is 0–10V DC with configurable standard signals of 0–5V DC, 1–5V DC and 0–10V DC. The output side provides two voltage-only channels with a nominal −10 to +10V DC range (−10 to +10V DC − 1 LSB), also configurable for 0–5V DC, 1–5V DC and 0–10V DC. A critically important distinction — and a frequent source of ordering errors — is that the Allen-Bradley 1746-FIO4V is voltage-output only; applications requiring a 0–20 mA current-loop output must specify the 1746-FIO4I instead.
The conversion architecture of the Allen-Bradley 1746-FIO4V is built for speed. Input resolution is 12-bit over 0–4095 counts, output resolution is 14-bit, and the module uses 16-bit two’s-complement binary communication with the processor. The internal channel update time is 512 microseconds, input step response is 100 milliseconds to 95%, and output step response is 2.5 milliseconds to 95% — an order-of-magnitude difference that reflects the module’s intended role: slow-changing process variables on the input, fast-acting control demands on the output. Overall input accuracy is ±0.440% of full scale at 25°C, while output accuracy reaches ±0.298% of full scale at the same temperature. The 7 kHz input bandwidth preserves signal fidelity while attenuating less than 1% of the input signal in the 0–1000 Hz range, rejecting the high-frequency EMI generated by adjacent motor cabling and switchgear. The Allen-Bradley 1746-FIO4V provides 500V DC isolation between field wiring and the backplane, protecting the processor from ground loops and field-side transients.
Technical Specifications
| Parameter Name | Parameter Value |
|---|---|
| Product Model | 1746- (Series A) |
| Manufacturer | Allen-Bradley / Rockwell Automation |
| Product Line | SLC 500 (Bulletin 1746) |
| Product Type | Fast analog combination input/output module |
| Number of Channels | 4 total — 2 inputs, 2 outputs |
| Input Type | 2 fast, differential, voltage or current; selectable by channel |
| Input Signal Range (Current) | 0–20 mA nominal; 0–30 mA absolute maximum |
| Input Signal Range (Voltage) | 0–10V DC; configurable 0–5V DC, 1–5V DC, 0–10V DC |
| Max Absolute Input Voltage | ±7.5V DC or 7.5V AC RMS |
| Output Type | 2 voltage outputs, grouped together |
| Output Signal Range | −10 to +10V DC (−1 LSB); configurable 0–5V DC, 1–5V DC, 0–10V DC |
| Output at Startup / Power-Up | 0V (outputs sit at zero until commanded) |
| Input Resolution | 12-bit (0–4095 counts) |
| Output Resolution | 14-bit |
| Data Communication Format | 16-bit two’s-complement binary |
| Internal Channel Update Time | 512 microseconds |
| Input Step Response | 100 milliseconds to 95% |
| Output Step Response | 2.5 milliseconds to 95% |
| Bandwidth (B) | 7 kilohertz |
| Input Accuracy | ±0.440% of full scale at 25°C |
| Output Accuracy | ±0.298% of full scale at 25°C |
| Isolation Voltage | 500V DC, field wiring to backplane |
| Input Filter Characteristic | Attenuates <1% of input signal in 0–1000 Hz range |
| Backplane Current (5V DC) | 55 mA |
| Backplane Current (24V DC) | 150 mA |
| Power Dissipation | Approx. 4.4W |
| Indicators | 1 LED status indicator |
| Configuration Method | Onboard DIP switches for input type; output range software configured |
| Compatible Processors | SLC 5/01, 5/02, 5/03, 5/04, 5/05 (fixed and modular chassis) |
| Chassis Compatibility | All 1746 SLC 500 chassis (4, 7, 10, 13-slot) |
| Slot Requirement | Single slot; any I/O slot except Slot 0 |
| Enclosure Type | Open type |
| Wire Size | 2.5 mm² (14 AWG) |
| Dimensions (H × W × D) | 12.7 × 5.1 × 15.2 cm (approx.) |
| Weight | 0.30–0.32 kg (300–320 g) |
| Operating Temperature | 0°C to 60°C (32°F to 140°F) |
| Storage Temperature | −40°C to 85°C |
| Relative Humidity | 5–95%, non-condensing |
| Certifications | UL Listed, CE Marked, CSA Certified |
| User Manual | Rockwell Publication 1746-UM009 |
| Lifecycle Note | Legacy platform; migration planning toward Compact 5000 I/O recommended |