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Phone: +86 16626708626Description
Key Technical Specifications
| Parameter | Specification |
| Module Type | Discrete Digital Input Module |
| Number of Inputs | 8 points |
| Voltage Category | 24V DC Sink (Sinking inputs accept current from sourcing devices) |
| Operating Voltage Range | 10 to 30V DC at 50 \textdegree C / 10 to 26.4V DC at 60 \textdegree C |
| Backplane Current Consumption | 50 mA at 5V DC (0 mA at 24V DC) |
| Signal Delay (Max) | ON delay: 8.0 ms | OFF delay: 8.0 ms |
| Off-State Voltage (Max) | 5.0V DC |
| Off-State Current (Max) | 1.0 mA |
| Nominal Input Current | 8 mA at 24V DC |
| Isolation Rating | 1,500V AC for 1 minute (Field-to-Backplane) |
Product Introduction & Supply Chain Strategy
The Allen-Bradley 1746-IB8 is an 8-channel discrete DC input module engineered for the SLC 500 PLC platform. It converts 24V DC field signals from pushbuttons, limit switches, photoelectric sensors, and proximity switches into logic-level signals across the 1746 backplane for central processor evaluation.
With Rockwell Automation having officially retired the SLC 500 family, maintaining New Surplus 1746-IB8 inventory is a vital risk-mitigation strategy for facilities running legacy automation racks. Procuring factory-fresh, uncommissioned surplus prevents unexpected line shutdowns and bypasses the severe failure rates associated with second-hand, thermally stressed pull-outs.
Installation & Configuration Guide
Stage 1: Pre-Installation (Prep & Safety)
- Perform Lock-Out/Tag-Out (LOTO) on the SLC 500 rack power supply and field sensor power buses.
- Put on a properly grounded ESD wrist strap before handling the replacement module.
- Photograph the existing terminal block wiring layout to ensure precise pin-to-wire mapping.
Stage 2: Removal
- Unfasten the top and bottom retaining screws on the removable terminal block (RTB) and carefully pull it off the front of the 1746-IB8.
- Depress the upper and lower module release latches on the SLC 500 rack chassis simultaneously.
- Pull the module straight out of the slot along its chassis guide rails to prevent backplane pin bending.
Stage 3: Installation (Clone & Seat)
- Verify that the replacement 1746-IB8 slot location matches the input addressing configured in RSLogix 500.
- Align the circuit board edges with the top and bottom slot guides of the 1746 chassis slot.
- Firmly push the module into the slot until both top and bottom latches snap into place securely.
- Align the pre-wired RTB onto the front terminal header and tighten the retaining screws to 0.5 N·m (4.4 lb·in).
Stage 4: Power-On & Testing
- Re-energize the 24V DC sensor field supply and verify field voltage presence across terminal connections.
- Apply 120/230V AC main power to the 1746 power supply and monitor the 1746-IB8 front status LEDs:
- Input Status LEDs (0–7): Toggle individual field sensors to confirm corresponding LED illumination.
- Access RSLogix 500 online mode, navigate to the I/O Data Table (
I:e.0/0throughI:e.0/7, whereeis the slot number), and verify bit updates in real time.
1746-IB8
1746-IB8
Firmware/Software Versions & Upgrade Notes
- Hardware Revision: Series A, B, and C modules function interchangeably across all SLC 500 chassis (1746-A4, A7, A10, A13).
- RSLogix 500 Configuration: The 1746-IB8 is a fixed-hardware discrete card that requires no software configuration file updates or firmware flashing. In RSLogix 500 I/O configuration, simply select
1746-IB8 8-Input (5/24VDC)for the respective slot. - Firmware Notes: Discrete I/O modules do not contain user-upgradable flash memory. Hardware swaps are plug-and-play, provided the input voltage ranges match.
Frequently Asked Questions (FAQ)
Q: Is this 1746-IB8 module a Brand New Surplus unit or a refurbished part?
A: This product is a Brand New Surplus unit. It is not used, not pulled from a decommissioned plant, and not refurbished. All modules undergo rigorous quality verification to ensure OEM-level reliability.
Q: What is the risk of using a cheaper refurbished 1746-IB8 input card?
A: Refurbished or used digital input cards frequently suffer from degraded optical isolators, cracked terminal housings, or intermittent trace damage caused by improper historical ESD handling. A failed input bit can halt an entire production line; paying a modest premium for verified New Surplus prevents thousands of dollars in emergency downtime costs.
Q: How do you verify the quality of legacy Allen-Bradley components?
A: Our technical team conducts comprehensive inbound inspection: checking original OEM anti-static packaging, inspecting backplane edge connectors for insertion wear, verifying terminal header integrity, and performing live 24V DC input handshake testing on a test chassis.
Q: What does “Sinking Input” mean for field wiring on the 1746-IB8?
A: Sinking inputs provide a path to DC Common. This means field sensors (such as PNP switches or dry contacts) must source current into the 1746-IB8 input terminals when activated.
Q: Is it safe to replace a 1746-IB8 card while the PLC system is under power?
A: No. Allen-Bradley SLC 500 racks do not support Hot-Swapping under power (RIUP). Removing or inserting any 1746 module while backplane power is active can cause electrical arcing, damaging the module, adjacent I/O cards, or the CPU. Always disconnect chassis power first.
Q: What warranty coverage comes with this New Surplus 1746-IB8?
A: Every 1746-IB8 New Surplus card comes backed by our 1-year comprehensive replacement warranty. If any channel or internal component fails under standard operating parameters, we will immediately issue a replacement card or full refund.
