Description
The Allen-Bradley 1746-IN16 is a 16-point discrete digital input module manufactured by Allen-Bradley, a brand of Rockwell Automation, for the SLC 500 family of programmable logic controllers. It accepts both 24 V AC and 24 V DC sinking signals in a single module, giving the controller visibility into pushbuttons, limit switches, proximity sensors, photoelectric sensors, and relay auxiliary contacts.
Designed to occupy one slot in any 1746 series modular chassis, the Allen-Bradley 1746-IN16 translates field-side on/off states into the processor’s input image table through optical isolation and filtering circuitry. Each of the sixteen channels carries its own status LED, so a technician can confirm whether a signal is actually reaching the module without opening a laptop or touching the program.
Application Scenarios
Consider a packaging line built around a SLC 500 rack, where the original design used 24 V DC proximity sensors for product presence and 24 V AC signals for the motor starter auxiliary contacts and the local pushbutton station. Two different signal types, two different module families, and a spare parts shelf carrying both.
The Allen-Bradley 1746-IN16 collapses that into one card. Sixteen channels, one common, and either AC or DC at the terminal—the module handles both. The maintenance team now stocks one part instead of two, and when a channel misbehaves, the per-point LED answers the first question immediately: is the signal getting to the rack, or is the problem inside the processor and program? On a line where a five-minute fault costs a shift’s production, that distinction alone pays for the module. The 8 mA nominal input current is also deliberately chosen: it is high enough to ignore the kind of electrical noise that makes cheaper inputs chatter, yet low enough that a two-wire sensor’s tiny off-state leakage does not falsely turn the point on.
Parameter
| Main Parameters | Value/Description |
|---|---|
| Product Model | Allen-Bradley 1746-IN16 |
| Manufacturer | Allen-Bradley (Rockwell Automation) |
| Product Category | Digital AC/DC input module, 16-point sinking |
| Compatible Platform | SLC 500 series, 1746 modular I/O chassis |
| Input Channels | 16 sinking inputs, 16 points per common |
| Input Type | Sinking (NPN / contact-to-common) |
| Operating Voltage | 10-30 V DC; 10-30 V AC |
| Nominal Input Current | 8 mA @ 24 V DC; 8 mA @ 24 V AC |
| Additional AC Input | 0.02 A (AC only, inrush per channel) |
| Max OFF-State Voltage | 3.0 V DC; 3.0 V AC |
| Max OFF-State Current | 1 mA DC; 1 mA AC |
| Signal Delay, DC | 15 ms ON / 15 ms OFF maximum |
| Signal Delay, AC | 25 ms ON / 25 ms OFF maximum |
| Backplane Current | 0.085 A @ 5 V DC; 0.0 A @ 24 V DC |
| Power per Point | 0.35 W |
| Total Power Dissipation | 6 W |
| Isolation | Optical coupling with filter circuitry, channel-to-backplane |
| Status Indication | 16 green LEDs, one per input channel |
| I/O Connection | 1746-HT and 1746-HCA cables / removable terminal block |
| Mounting | Single-slot module, any 1746 chassis slot |
| Operating Temp. | 0 °C to +60 °C |
| Humidity | 5-95% RH, non-condensing |
| Certifications | UL Listed; CSA; CE; C-TICK; cUL |
| Programming Software | RSLogix 500 |
| Dimensions | Approximately 140 × 130 × 40 mm (5.7 × 5.1 × 1.5 in) |
| Weight | Approximately 0.23 kg (0.51 lb) |
| Product Status | Discontinued by Rockwell (August 2018); End-of-Life |