Product Overview
The Allen-Bradley 1747-SN/B is a Remote I/O scanner and Data Highway Plus interface module for the SLC 500 platform. As a Series B unit, it carries the /B firmware revision. This module lets an SLC processor talk to remote 1746 I/O chassis and other RIO-compatible devices over the A-B Remote I/O link. It also supports DH+ networking. If you run a legacy SLC 500 line, this scanner is often the bridge that keeps remote I/O alive.
Rockwell Automation discontinued the 1747-SN/B on 2024-03-31. The listed engineering replacement is the 5069-AENTR. That means new stock is finite. For plants that still depend on SLC 500 remote racks, sourcing a tested spare is a practical risk-reduction move. Oil AutoTech supports oil, gas and industrial automation teams with fast-dispatch spares and hands-on technical selection help.
Technical Specifications
RIO Baud Rates and Distance
The module supports RIO baud rates of 57.6, 115.2 and 230.4 Kbps. Maximum RIO distance is 3048 m. In practice, the baud rate you choose trades scan speed against cable length. Longer runs favor lower baud rates for signal integrity. Shorter, faster links favor 230.4 Kbps when your remote chassis sit close to the processor.
Logical Racks and Block Transfer
The 1747-SN/B handles up to 4 logical racks, giving 32 input and 32 output words of discrete data. Series B firmware also supports block transfer up to 64 words. That matters when analog or specialty modules sit in remote racks. Discrete data moves fast, while block transfer carries the larger data blocks those modules need.
Backplane Power Draw
Backplane current draw is 600 mA at 5V DC and 90 mA at 24V DC. The 1746 chassis backplane supplies 5.1V DC at 10A and 24V DC at 2.88A to all modules. Always total the load of every module in the chassis before adding this scanner. The module occupies a single SLC 500 chassis slot. Slot 0 stays reserved for the processor or a 1747-ASB adapter.
DH+ Node Addressing
DH+ node addressing is set with a DIP switch. That gives you direct, hardware-level control over the node address without software. Confirm the address plan before installation so the scanner does not clash with other DH+ nodes on the link.
Industry Applications
Oil and Gas Remote Racks
In oil and gas facilities, I/O often sits far from the control room. The 3048 m RIO distance and 57.6 Kbps option let the 1747-SN/B serve remote wellhead or pipeline racks. This is exactly where fast-dispatch spares matter. When a scanner fails, production waits.
Water Treatment and Pump Stations
Water plants use SLC 500 systems with distributed pump stations. The scanner links those remote chassis back to a central processor. Its 32 in/32 out word capacity covers many pump and valve status points.
Manufacturing Cell Integration
Discrete manufacturing cells with remote 1746 racks use this module for RIO and DH+ connectivity. Block transfer up to 64 words supports analog modules in those racks.
Installation and Setup
Mount the module in a 1746 chassis. The 1746-A4, -A7, -A10 and -A13 chassis offer 4, 7, 10 and 13 slots. All are panel-mount. Do not install, remove or wire the module with power applied. It is not hot-swappable. Set the DH+ node address with the DIP switch before power-up. Use removable terminal blocks for field wiring. Bulletin 1492 pre-wired interface is available for field wiring. Field-side load power needs an external supply. The backplane only provides logic power.
Maintenance and Reliability
Inspect the module periodically for secure seating and clean connections. Keep the panel within the 0 to 60 C operating range. Storage range is -40 to 85 C, and humidity should stay at 5-95% RH non-condensing. Since the product is discontinued, treat every spare as a lifecycle asset. A ready-to-ship spare on the shelf protects uptime better than a rushed search after a failure. Fast dispatch, worldwide.
Compatibility and Integration
The 1747-SN/B works within the SLC 500 / Bulletin 1747 family. It communicates over the A-B Remote I/O link and DH+ network. It fits a single slot in a 1746 chassis alongside other 1746 I/O modules. Slot 0 is reserved for the processor or a 1747-ASB adapter. Plan your chassis power budget using the 600 mA at 5V DC and 90 mA at 24V DC draw. For DH+ and RIO links, confirm cabling and connection hardware with your supplier before ordering.
Selection Guide
Before you buy, verify your chassis model, slot availability and backplane power headroom. Confirm your RIO baud rate and distance needs. Check the DH+ node address plan. If you are migrating, the listed engineering replacement is the 5069-AENTR. For legacy SLC 500 support, contact Oil AutoTech today for pricing and availability.
FAQs
Is the 1747-SN/B still in production?
No. Rockwell Automation discontinued it on 2024-03-31. The listed engineering replacement is the 5069-AENTR. Availability now depends on remaining stock and the secondary market.
What is the maximum RIO distance for this scanner?
The maximum RIO distance is 3048 m. Supported RIO baud rates are 57.6, 115.2 and 230.4 Kbps.
How much backplane current does the 1747-SN/B draw?
It draws 600 mA at 5V DC and 90 mA at 24V DC from the 1746 chassis backplane.
Can I hot-swap this module?
No. Do not install, remove or wire it with power applied. It is not hot-swappable.
What data capacity does Series B firmware support?
It supports up to 4 logical racks, 32 input and 32 output words of discrete data, plus block transfer up to 64 words.
