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3. Key Technical Specifications
| Parameter | Value |
|---|---|
| Catalog Number | 1794-IB16 |
| Number of Inputs | 16 (current sinking) |
| On-State Voltage, Min | 10 V DC |
| On-State Voltage, Nom | 24 V DC |
| On-State Voltage, Max | 31.2 V DC |
| On-State Current, Min | 2.0 mA |
| On-State Current, Nom | 8.0 mA @ 24 V DC |
| On-State Current, Max | 12.0 mA |
| Off-State Voltage, Max | 5.0 V DC |
| Off-State Current, Max | 1.5 mA |
| Input Impedance, Max | 4.6 kΩ |
| FlexBus Current | 30 mA @ 5 V DC |
| Power Dissipation, Max | 6.1 W @ 31.2 V DC |
| Thermal Dissipation, Max | 20.8 BTU/hr @ 31.2 V DC |
| Isolation Voltage | 50 V continuous, basic insulation (field to system); no channel-to-channel isolation |
| Recommended Terminal Base | 1794-TB3, 1794-TB3S, 1794-TB3K, 1794-TB3SK |
| Operating Temperature | 0…55 °C (32…131 °F) |
| Storage Temperature | –40…85 °C (–40…185 °F) |
| Dimensions (approx., installed) | 94 × 94 × 69 mm (3.7 × 3.7 × 2.7 in.) |
| Keyswitch Position | 2 |
4. Product Introduction
The Allen-Bradley 1794-IB16 is a 16-point 24 V DC sinking digital input module for the FLEX I/O platform. It accepts discrete signals from sensors, switches, and other field devices operating in the 10…31.2 V DC range.
The module mounts on a compatible 1794 terminal base and communicates over the FLEX I/O backplane to any FLEX adapter (EtherNet/IP, ControlNet, DeviceNet, etc.). It is used in distributed I/O applications where compact size, modular expansion, and reliable 24 V DC input sensing are required. Status indicators on the module face provide immediate visual confirmation of each input state.
5. Troubleshooting Quick Reference
| Symptom | Possible Cause | Relevance to this Part | Quick Check Method | Recommendation |
|---|---|---|---|---|
| No input status LEDs | Field power missing or wiring error | ❌ Low | Measure 24 V DC at terminal base field power terminals | Verify external field supply first |
| Input LED on but controller shows off | Filter time or configuration mismatch | ✅ Medium | Check input filter settings in the adapter/controller | Adjust filter time or re-download configuration |
| Intermittent input reading | Noise, loose terminal, or marginal voltage | ✅ High | Measure voltage at input terminal under load; check torque | Tighten terminals; add shielding or filtering |
| Module not recognized | Wrong keyswitch or terminal base | ✅ High | Confirm keyswitch position 2 and correct terminal base | Install on 1794-TB3/TB3S family base |
| High power dissipation / heat | All inputs energized at high voltage | ✅ Medium | Calculate total current and ambient temperature | Stay within 6.1 W dissipation limit |
| Channel stuck on or off | Failed input circuit or shorted field device | ✅ High | Swap field wiring to another channel | Replace module if fault follows the channel |
If the module still does not report inputs correctly after these checks, capture the adapter diagnostics, input voltage readings, and photos of the wiring, then contact technical support.
1794-IB16
1794-IB16
6. Frequently Asked Questions (FAQ)
Q: What terminal base does the 1794-IB16 require?
A: Use a 1794-TB3, 1794-TB3S, 1794-TB3K, or 1794-TB3SK terminal base. Other bases may not provide the correct wiring or keying.
Q: Is this a sinking or sourcing input module?
A: It is a current-sinking input module. Field devices must source current into the module inputs (typical for PNP sensors).
Q: Can I hot-swap the 1794-IB16?
A: Yes. FLEX I/O supports Removal and Insertion Under Power (RIUP) when the proper terminal base and adapter are used. Follow Rockwell guidelines for safe removal.
Q: What is the difference between the 1794-IB16 and 1794-IB16D?
A: The 1794-IB16 is the standard 16-point sink input module. The 1794-IB16D adds diagnostics (open-wire, short-circuit, reverse polarity) and requires a different terminal base (1794-TB32 series).
Q: Does it have channel-to-channel isolation?
A: No. Isolation is provided between the field side and the system (backplane) only. Individual channels share a common.
Q: What is the maximum input voltage?
A: 31.2 V DC. Do not exceed this value or the module may be damaged.
Q: Is the 1794- still in production?
A: Yes. It remains an active FLEX I/O digital input module. New original and new-surplus units are available.
