Allen-Bradley 1746-IO8 Combination Input/Output Module – SLC 500 Series
When a discrete I/O module fails mid-shift on an automotive transfer line or a packaging conveyor, the entire production cell goes dark. Operators lose visibility into sensor states, actuators freeze in place, and every minute of unplanned downtime translates directly into scrapped product and missed delivery windows. The Allen-Bradley 1746-IO8 is the module that prevents that scenario — a field-proven, slot-efficient combination I/O card that keeps your SLC 500 rack talking to the real world without compromise.
Within the SLC 500 family, the 1746-IO8 occupies a precise engineering niche: it consolidates four 24 VDC sink/source inputs and four relay or transistor outputs into a single slot, making it the preferred choice for machine builders who need balanced I/O density without dedicating two slots to separate input and output cards. Deployed across hundreds of thousands of installations globally since the SLC 500 platform’s commercial introduction, this module remains a cornerstone of legacy system maintenance, retrofit projects, and spare-parts inventories in discrete manufacturing worldwide.
Technical Specifications
Electrical
- Input Channels: 4 × DC inputs
- Output Channels: 4 × DC outputs
- Input Voltage Range: 10–30 VDC (nominal 24 VDC)
- Input Current (ON state): ≥ 6 mA at 24 VDC
- Output Voltage Range: 10–30 VDC
- Output Current Rating: 1 A per point, 4 A per module
- Output Type: Transistor (sourcing or sinking, per variant)
- Backplane Current Draw: 100 mA at 5 VDC; 0 mA at 24 VDC
- Isolation: 1500 VAC optical isolation (field side to backplane)
Mechanical
- Form Factor: Single-slot SLC 500 / 1746 rack module
- Connector: Removable 20-pin terminal block (RTB)
- Weight: Approximately 400 g (with RTB)
- Dimensions: Standard 1746 single-slot profile
Environmental
- Operating Temperature: 0 °C to +60 °C
- Storage Temperature: −40 °C to +85 °C
- Relative Humidity: 5–95% non-condensing
- Vibration: 2 g @ 10–500 Hz (IEC 68-2-6)
- Shock: 30 g operational (IEC 68-2-27)
Certifications & Standards
- UL Listed, CE Marked, CSA Certified
- Compliant with IEC 61131-2 (Programmable Controllers — Equipment Requirements)
- RoHS compliant (per applicable revision)
Key Features & Benefits
- Single-slot I/O consolidation — Combines 4 inputs and 4 outputs in one rack slot, freeing adjacent slots for expansion modules or reducing overall rack size by up to 50% compared to using separate 1746-IB8 and 1746-OB8 cards.
- 1500 VAC optical isolation — Field-side signals are fully isolated from the backplane, protecting the SLC 500 processor from transient spikes common in motor-drive and solenoid-heavy environments, meeting IEC 61131-2 isolation requirements.
- Hot-swap compatible RTB — The removable terminal block allows field wiring to be disconnected and reconnected without disturbing the module, reducing rewiring time during replacement to under five minutes.
- 1 A per output point — Each output channel sustains 1 A continuous, sufficient to drive 24 VDC solenoid valves, pilot relays, and indicator lamps directly without interposing relays in the majority of machine I/O applications.
- Broad input voltage window (10–30 VDC) — Accommodates real-world 24 VDC bus fluctuations without nuisance faults, a critical advantage in facilities where power supply regulation is inconsistent across machine generations.
- Direct SLC 500 backplane compatibility — Plug-and-play with all 1746 fixed and modular racks; no firmware update or configuration file change required when replacing an identical module, minimizing MTTR in emergency maintenance scenarios.
Industry & Equipment Applications
- Automotive Manufacturing — Transfer line end-of-line test stations, body-in-white welding cell interlocks, and paint shop conveyor position sensing where balanced I/O density per slot is critical.
- Food & Beverage Processing — Filling machine cap-presence detection and reject gate control, bottling line conveyor divert logic, and CIP valve sequencing in washdown-adjacent control panels.
- Packaging Machinery — Cartoning machine flap-fold sensor inputs paired with glue-gun enable outputs, case erector limit switch monitoring, and palletizer layer-complete signaling.
- Water & Wastewater Treatment — Pump run/fault status inputs combined with valve open/close command outputs in lift station RTU panels where rack space is constrained.
- Material Handling & Logistics — Sortation conveyor divert gate control, accumulation zone sensor inputs, and dock leveler position monitoring in distribution center automation systems.
- Oil & Gas Surface Equipment — Wellhead skid instrument status inputs and shutdown valve command outputs in SLC 500-based SCADA remote I/O panels operating in Class I, Division 2 enclosures (with appropriate barriers).
System Integration & Compatible Parts
Compatible SLC 500 Processors: 1747-L20, 1747-L30, 1747-L40, 1747-L511, 1747-L514, 1747-L524, 1747-L531, 1747-L532, 1747-L541, 1747-L542, 1747-L543, 1747-L551, 1747-L552, 1747-L553
Compatible Racks: 1746-A4, 1746-A7, 1746-A10, 1746-A13 (any standard 1746 modular rack)
Upstream Components: 1747-SN Scanner (for remote I/O), 1746-P1 / 1746-P2 / 1746-P4 Power Supplies
Downstream Field Devices: 24 VDC 2-wire and 3-wire proximity sensors (NPN/PNP), photoelectric sensors, solenoid valves (≤ 1 A coil), pilot lights, and interposing relay coils
Equivalent / Substitute Models:
- 1746-IO12 — Drop-in upgrade to 6 inputs + 6 outputs; requires verifying rack slot availability and I/O map address reassignment in the RSLogix 500 program.
- 1746-IO12DC — DC-only variant with higher output current; verify output type compatibility before substitution.
- Separate 1746-IB8 + 1746-OB8 pair — Functional equivalent using two slots; use when I/O count expansion is anticipated or when input/output ratios differ from 4:4.
Our Quality Assurance Process
- Visual & Mechanical Inspection — Each unit is examined for PCB damage, connector pin integrity, label legibility, and RTB locking mechanism function before any electrical testing begins.
- Powered Functional Test — The module is seated in a live 1746 rack with a known-good SLC 500 processor. All input channels are exercised with calibrated 24 VDC signals; all output channels are verified under resistive load using a data logger to confirm switching response and current delivery.
- Firmware & Revision Verification — Hardware revision and series letter are documented and cross-referenced against Rockwell Automation product notices to confirm no known field issues apply to the specific unit being shipped.
- Packaging & ESD Protection — Tested units are wrapped in anti-static bags, placed in foam-lined boxes, and labeled with revision data. Export cartons include desiccant packs for ocean freight shipments.
Available Documentation: Test report, product photos (pre-shipment), Rockwell Automation datasheet reference, certificate of conformance (on request), and commercial invoice with country of origin declaration.
How to Order
- Submit Your Inquiry — Use the contact form on this page or email support@konmask.com with your required quantity, target delivery date, and destination country.
- Receive Your Quote — Our team will respond within 24 hours with pricing, lead time, available stock condition (new / tested surplus / refurbished), and shipping options including DHL Express, FedEx International, and sea freight for bulk orders.
- Confirm & Ship — Upon order confirmation and payment, units are prepared, tested, and dispatched with full tracking. Typical export packing and dispatch time is 1–3 business days from payment clearance.
Why Choose Konmask.com?
- Specialized in Industrial Automation Components — We focus exclusively on PLC, DCS, and control system hardware. Every team member understands the technical context of what they are sourcing and selling.
- Verified Stock with Functional Testing — We do not list modules we have not physically inspected. Every 1746-IO8 shipped from Konmask.com has passed a powered functional test on actual SLC 500 hardware.
- Global Export Experience — We ship to over 40 countries with full commercial documentation, including packing lists, commercial invoices, and certificates of origin suitable for customs clearance.
- Responsive Technical Support — Have a question about compatibility, revision differences, or substitution options? Our engineers respond to technical inquiries within one business day.
- Flexible Order Quantities — Whether you need a single emergency replacement or a standing order of 50 units for a plant-wide retrofit, we accommodate both without minimum order quantity restrictions.
Frequently Asked Questions
Q: Is the Allen-Bradley 1746-IO8 compatible with all SLC 500 processor series, including the older 1747-L20?
A: Yes. The 1746-IO8 is compatible with all SLC 500 processors from the original 1747-L20 through the latest 1747-L55x series. The module communicates over the standard 1746 backplane and requires no processor firmware update. The only prerequisite is that the I/O address assigned to the slot in your RSLogix 500 program matches the physical slot position in the rack.
Q: What is the difference between the 1746-IO8 and the 1746-IO8DC, and can I use one as a direct replacement for the other?
A: The 1746-IO8 uses relay outputs on some variants, while the 1746-IO8DC specifies transistor (DC) outputs throughout. Before substituting, verify the output type your application requires: relay outputs handle AC and DC loads with higher inrush tolerance, while transistor outputs offer faster switching and longer service life for high-cycle applications. Check your existing wiring diagram and RSLogix 500 I/O configuration before swapping.
Q: How do I source a tested surplus 1746-IO8 for an emergency plant breakdown, and what lead time can I expect from Konmask.com?
A: Email support@konmask.com or call +0086 19859288691 with your urgency level. For in-stock units, we can typically dispatch within 24–48 hours of payment confirmation. DHL Express delivery to most Asian, European, and North American destinations takes 3–5 business days. We will confirm exact availability and transit time in our quote response, which you will receive within 24 hours of inquiry.
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Original Source: https://Konmask.com
Contact: support@konmask.com | +0086 19859288691
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