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Key Technical Specifications
- Catalog Number: 1746-IV16
- Manufacturer: Allen-Bradley
- Product Family: SLC 500
- Module Type: Digital DC input module
- Input Count: 16
- Input Type: Sourcing
- Input Voltage Range: 10-30 V DC
- Nominal Input Voltage: 24 V DC
- Nominal Input Current: 8 mA at 24 V DC
- Backplane Current at 5 VDC: 85 mA
- Off-State Current: 1 mA max
- Signal Delay: 8 ms ON, 8 ms OFF
Product Introduction
The Allen-Bradley 1746-IV16 is a 16-point sourcing DC input module for the SLC 500 platform. It accepts 24 VDC field signals from sensors, switches, and other discrete devices and converts them into PLC input data.
This module is used in legacy SLC 500 panels where the wiring is set up for sourcing inputs. The 1746-IV16 supports 10-30 VDC operation, 8 mA nominal input current, and standard SLC backplane integration, which makes it a straightforward replacement when the exact input style matters.
Troubleshooting Quick Reference
| Symptom | Possible Cause | Relevance to this Part | Quick Check Method | Recommendation |
|---|---|---|---|---|
| Input LED never turns on | Missing field supply or open wiring | ✅ High | Measure 10-30 VDC at the input circuit with a meter | Check field power, fuse, and wiring first |
| Input LED on, PLC bit stays off | Slot mapping or logic issue | ⚠️ Medium | Verify the processor address and rack slot assignment | Confirm the program is looking at the right word |
| One channel stuck ON | External device leaking voltage or shorted field wire | ✅ High | Remove the wire and recheck the status | Inspect the sensor or switch before replacing the module |
| Several inputs dead at once | Common feed lost or supply failed | ✅ High | Check the common terminal and supply continuity | Restore the common feed before condemning the card |
| Inputs chatter or flicker | Noisy field wiring or marginal voltage | ✅ High | Measure voltage under load and inspect cable routing | Fix the wiring quality before swapping the module |
| All inputs dead after install | Wrong module type or no rack power | ✅ High | Confirm part number and verify chassis power | Check the PSU and exact catalog number |
If you are stuck, send photos of the wiring, terminal block, and processor diagnostics to technical support.
- 1746-IV16
- 1746-IV16
Frequently Asked Questions
Q: What does the 1746-IV16 do?
It is a 16-point 24 VDC sourcing input module for the SLC 500 family.
Q: Is it the same as a sinking input card?
No. Sourcing and sinking are opposite wiring styles. If the machine is wired for sinking inputs, this is not the right card.
Q: Is this part still made by Rockwell?
No. It is a discontinued SLC 500 module, so most available inventory is surplus or refurbished.
Q: What devices normally go on this module?
Typical field devices include 24 VDC sensors, push buttons, limit switches, and other discrete inputs designed for sourcing circuits.
Q: Can I swap it into any SLC 500 rack?
Usually yes, if the chassis and program match. Still verify the slot, input type, and field wiring before power-up.
Q: Why do some listings call it a 16-point module and others call it a 24 VDC input card?
Both descriptions refer to the same basic function. “16-point” means 16 input channels, and “24 VDC” tells you the field voltage class.
Q: What should I verify before ordering?
Check the exact part number, the sourcing input style, the 10-30 VDC range, and the existing wiring scheme. The biggest mistake is ordering a card that matches the slot but not the field wiring.
