Purchase now: Allen Bradley 1747-DSN DIO Scanner
Purchase now: Atlantechdrives provides you the 1747-DSN, a highly specialized Distributed I/O (DIO) Scanner module manufactured by Allen Bradley for the legacy SLC 500 automation platform. Specifically engineered for early architecture processors like the SLC 5/01 and 5/02, the 1747-DSN acts as a high-speed network master. It allows the local PLC to exchange continuous control information with up to 30 external, distributed I/O blocks. By decentralizing the I/O hardware, automation engineers can mount the input and output blocks directly on the machine frame—closer to the physical sensors and actuators—drastically reducing the amount of copper field wiring that must be routed back to the main electrical cabinet.
Technical Specifications of the 1747-DSN
The 1747-DSN utilizes Allen Bradley’s proprietary DIO Link, communicating with distributed blocks in a rapid «round-robin» polling sequence. It occupies a single slot in the local SLC chassis and operates independently of the standard DH-485 network.
- Part Number: 1747-DSN
- Module Type: Distributed I/O (DIO) Scanner
- Compatible Processors: SLC 5/01, SLC 5/02
- Network Protocol: Allen Bradley DIO Link
- Communication Speed: Fixed at 230.4 kbps
- Maximum Cable Distance: 2,500 feet (762 meters)
- Cable Requirement: Belden 9463 Twinaxial («Blue Hose»)
- Network Connections: 6-Pin Phoenix connector
Expert Tips: DIO vs. RIO Networking Protocols
A frequent point of confusion for maintenance technicians is mixing up legacy network protocols. Expert Tip: While the 1747-DSN uses the exact same physical cable (the famous Belden 9463 «Blue Hose») as the more common Universal Remote I/O (RIO) network, the communication protocols are entirely different and incompatible. The 1747-DSN operates exclusively on the DIO link. It cannot communicate with RIO adapters like the 1747-ASB or modern Flex I/O modules. When troubleshooting a legacy network, always verify whether the hardware is part of a DIO Scanner system or a RIO Scanner system (1747-SN) to ensure you are consulting the correct manual and utilizing the proper addressing structure.
Installation Advice: Block Addressing and Termination
The DIO network is highly specific regarding device addressing. Because the 1747-DSN scanner operates at a fixed baud rate of 230.4K, all connected slave I/O blocks must be hardware-configured to match this exact speed. Furthermore, the external I/O blocks must be addressed strictly as blocks 1 through 15, and 17 through 31. Address 16 is reserved by the system and cannot be used. Finally, just like all linear twinaxial networks, you must install terminating resistors at the extreme physical ends of the cable run to prevent signal bounce and maintain control data integrity.
Frequently Asked Questions (FAQs)
Q: Can I use the 1747-DSN in an expansion chassis?
A: Yes, the scanner can be installed in any available slot of the local SLC chassis or an adjacent expansion chassis, provided you do not exceed the backplane power supply limits of the rack.
Q: Is this module compatible with modern ControlLogix systems?
A: No. The 1747-DSN and the DIO protocol are legacy technologies specific to the early SLC 500 ecosystem and are not natively supported by modern Logix PACs or modern distributed I/O families.
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This DeviceNet scanner requires a reliable modular frame; it is technically designed to be housed within a 1746-A7 SLC 500 chassis.
