What the 1747-SCNR ControlNet Scanner Does
If your SLC 500 line still runs ControlNet devices, the scanner slot is the one you cannot leave empty. The Allen-Bradley 1747-SCNR is a ControlNet scanner module 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.
This is a buyer’s guide for maintenance engineers and MRO buyers who need to confirm fit, function and availability before ordering.
Technical Specifications
| Specification | Value |
|---|---|
| Product Type | ControlNet Scanner Module |
| Series | SLC 500 / Bulletin 1747 |
| Network | ControlNet |
| Data Rate | 5 Mbps |
| Connectors | 2 x BNC (coaxial) |
| Backplane Current | 900 mA @ 5V, 90 mA @ 24V |
| Nodes | Up to 99 |
| Processor Compatibility | SLC 5/02 to 5/05 |
| Operating Temperature | 0 to 60 C |
| Storage Temperature | -40 to 85 C |
| Humidity | 5-95% RH non-condensing |
What These Specs Mean in Practice
The 5 Mbps rate and dual BNC ports define how the scanner joins the ControlNet trunk. The two connectors support standard coaxial trunk and drop connections, so plan your taps and terminators around them.
Power draw is modest: 900 mA at 5V and 90 mA at 24V from the backplane. That matters when you total the load on a 1746 chassis, which supplies 5.1V DC @ 10A and 24V DC @ 2.88A across its slots.
Node count reaches up to 99, so the scanner can supervise a large ControlNet segment. Processor compatibility spans SLC 5/02 through 5/05 — confirm your CPU before purchase.
Installation and Slot Rules
The module mounts in a 1746 chassis (1746-A4, -A7, -A10 or -A13, with 4, 7, 10 or 13 slots). All chassis are panel-mount. Slot 0 stays reserved for the processor or a 1747-ASB adapter.
The 1747-SCNR is not hot-swappable. Do not install, remove or wire the module with power applied. Field wiring uses removable terminal blocks, and a Bulletin 1492 pre-wired interface is available for cleaner panel builds.
Where This Scanner Fits
Typical duty is legacy SLC 500 installations where ControlNet links drives, remote I/O and operator interfaces. Oil, gas and process plants often keep these networks running long after the original build, which is why a spare scanner on the shelf protects production.
Because the 1747-SCNR is discontinued (per-model date: 2015-12-31) with an engineering replacement, sourcing is the real constraint. Oil AutoTech helps with hands-on technical selection and fast dispatch, worldwide, so you can match the right module to your chassis and CPU.
Maintenance and Reliability
Inspect the module and its BNC connections periodically for contamination and mechanical stress. Keep panel temperature within 0 to 60 C and humidity within 5-95% RH non-condensing. Follow the manufacturer’s safety manual for all service work.
Selection Checklist
Before ordering, verify: your processor is SLC 5/02 to 5/05; your chassis is a 1746 series; you have a free slot beyond Slot 0; and your ControlNet segment stays within 99 nodes. Please verify current lifecycle status and availability with Oil AutoTech before ordering.
Contact Oil AutoTech today for pricing and availability.
