What Is the 1747-SCNR?
The Allen-Bradley 1747-SCNR is a ControlNet scanner module built for the SLC 500 (Bulletin 1747) platform. It lets an SLC 500 processor act as a ControlNet network scanner, communicating with ControlNet devices over coaxial BNC ports at 5 Mbps. For maintenance engineers running legacy SLC 500 lines, this module is often the bridge between the processor and a plant-wide ControlNet segment.
Rockwell Automation discontinued this module on December 31, 2015. The official per-model page confirms that date, and the listed replacement path is an engineering replacement. If your line still depends on the 1747-SCNR, planning a replacement or securing a tested spare is now a practical reliability decision, not a future one.
Technical Specifications Breakdown
ControlNet Communication at 5 Mbps
The module runs ControlNet at 5 Mbps over two BNC coaxial ports. In practice, this gives deterministic, high-speed data exchange between the SLC 500 processor and remote ControlNet devices. Two ports also support redundant or daisy-chain cabling layouts common on process lines.
Backplane Power Draw
The 1747-SCNR draws 900 mA at 5V DC and 90 mA at 24V DC from the 1746 chassis backplane. When you swap modules, confirm the chassis power budget still covers the full module set, especially in fully loaded 13-slot racks.
Network Capacity up to 99 Nodes
With support for up to 99 nodes, one scanner can serve a large ControlNet segment. That scale matters on oil, gas and heavy industrial sites where many remote I/O drops share one network.
Processor Compatibility
The module works with SLC 5/02 through SLC 5/05 processors. Verify your exact processor model before ordering, because compatibility is limited to that range.
Where the 1747-SCNR Fits in Real Plants
Oil and Gas Remote I/O
On a tank farm or pipeline skid, the scanner links the SLC 500 processor to ControlNet-connected remote I/O. The 5 Mbps rate and 99-node capacity keep scan times predictable across long cable runs.
Legacy Line Upgrades
When a plant standardizes on newer control platforms, the 1747-SCNR often stays in service during phased migration. Keeping a tested spare on the shelf avoids unplanned downtime while the upgrade is planned.
Continuous Process Reliability
In continuous processes, a failed scanner can stop the whole segment. Because the module is discontinued, sourcing a reliable spare quickly is the difference between a short repair and a long outage.
Installation and Setup Notes
The 1747-SCNR is not hot-swappable. Do not install, remove or wire the module with power applied. Always isolate the 1746 chassis before service work. Slot 0 stays reserved for the processor or a 1747-ASB adapter, so plan module placement accordingly. The 1746 chassis supplies 5.1V DC @ 10A and 24V DC @ 2.88A across the backplane; field-side load power still needs an external supply. Removable terminal blocks simplify field wiring, and Bulletin 1492 pre-wired interface options can reduce wiring time.
Maintenance and Reliability Guidance
Inspect the module and its BNC connections periodically for contamination, loose seating and cable strain. ControlNet coaxial cabling is sensitive to termination quality, so check terminators and cable routing during routine rounds. Keep the enclosure within the family operating range of 0 to 60 C and 5-95% RH non-condensing. Because the unit is discontinued, treat every installed module as a critical spare candidate. Fast dispatch, worldwide, matters when a scanner fails on a running line. Contact Oil AutoTech today for pricing and availability.
Compatibility and Integration
The 1747-SCNR integrates with SLC 5/02 to 5/05 processors and mounts in 1746-A4, -A7, -A10 or -A13 chassis. It communicates over ControlNet via BNC coaxial ports. When wiring into a ControlNet network, confirm cable types, terminators and any connection modules with your supplier before installation.
Selection Checklist Before You Buy
Confirm your processor is an SLC 5/02 through 5/05, verify available slots and backplane power in your 1746 chassis, and check that your ControlNet cabling and node count match the module’s 99-node capacity. Since the 1747-SCNR is discontinued, ask about the engineering replacement path and current stock. Oil AutoTech offers hands-on technical selection help and ready-to-ship spares for oil, gas and industrial automation.
Frequently Asked Questions
Is the 1747-SCNR still in production?
No. Rockwell Automation discontinued it on December 31, 2015. Verify current availability and replacement options with Oil AutoTech before ordering.
Which processors work with this module?
It is compatible with SLC 5/02 through SLC 5/05 processors.
Can I hot-swap the module during operation?
No. Do not install, remove or wire it with power applied. Isolate the chassis first.
What communication speed does it support?
It operates on ControlNet at 5 Mbps through two BNC coaxial ports.
How many nodes can one scanner handle?
Up to 99 nodes on the ControlNet network.
