Technical Specifications

Main Features and Advantages

Two functions in one slot: the clearest advantage of the 1746-NIO4I​ is slot economy. In a 1746-A4 or 1746-A7 chassis where every position is precious, combining measurement and command on one board frees a slot for additional digital I/O, a communication module or future expansion. For closed-loop applications — tank level with a modulating inlet valve, pipe pressure with a pump VFD, oven temperature with a gas control valve — the 1746-NIO4I​ delivers exactly the channel count such a loop needs without wasting half of two separate cards.Flexible input configuration: each of the two input channels on the 1746-NIO4I​ can be independently set for voltage or current, so a single module can accept a 4–20 mA pressure transmitter on channel 0 and a 0–10V position feedback signal on channel 1. Range selection is mandatory during commissioning — a module left at its default voltage setting will not read a current loop correctly — but once configured, the Sigma-Delta converter delivers 16-bit resolution with excellent repeatability of ±1 LSB.Current outputs built for long cable runs: the output stage of the 1746-NIO4I​ is hardware-dedicated to current, and that is a deliberate engineering choice. A 4–20 mA command signal is far less susceptible to voltage drop and electromagnetic interference than a voltage signal, so it remains accurate even when the driven device sits hundreds of feet away across a plant. With a 0 to 500 ohm load capability and 5% over-range headroom, the 1746-NIO4I​ can drive VFD analog inputs, proportional valves, signal isolators, chart recorders and panel meters directly.Signal integrity in noisy panels: analog signals are vulnerable, and the 1746-NIO4I​ addresses this with 105 dB common mode rejection and 55 dB normal mode rejection at 60 Hz, plus 500V isolation between the field side and the backplane. A 10 Hz input filter smooths process noise without excessive lag, and continuous overvoltage protection to 220V AC/DC guards against accidental miswiring. The result is stable readings in cabinets that also contain contactors, drives and switching power supplies.

Application Field

Closed-loop process control: the 1746-NIO4I​ is at its best where a measured variable must drive a corrective action. In a water booster station, one input reads discharge pressure from a 4–20 mA transmitter while one output commands the pump VFD speed reference, forming a complete PID loop in a single slot. The same pattern applies to chemical dosing, where flow feedback commands a metering pump, and to HVAC systems, where temperature or static pressure modulates a damper actuator or valve positioner.Machine and equipment control: packaging machines, extruders, presses and web-handling equipment use the 1746-NIO4I​ for tension, position and speed coordination. A dancer-position or load-cell feedback signal enters on one channel while an analog speed or torque command leaves on an output, giving the SLC processor the analog authority that purely digital control cannot provide. The 2.5 ms output step response is quick enough for most machine-level modulation duties.Retrofit and panel densification: many plants install the 1746-NIO4I​ specifically because an existing SLC 500 rack is full. Replacing separate input and output cards with a single 1746-NIO4I​ recovers a slot without rewiring the field side, which is far less disruptive than adding an expansion chassis or migrating the platform. Because the module also works with fixed-style SLC 500 controllers, it serves as a practical expansion path for brick-style systems.Instrumentation interfacing: beyond control loops, the 1746-NIO4I​ commonly interfaces chart recorders, remote panel meters, signal isolators and third-party controllers that accept or generate standard current signals, making it a general-purpose analog gateway within SLC 500 architectures.