Overview
The Allen-Bradley 1794-ASB /D is a remote I/O adapter module engineered for distributed input/output control in industrial automation systems. Part of the FLEX I/O 1794 product family, this adapter enables communication between programmable controllers (PLC-5, SLC-500, ControlLogix) and remote FLEX I/O racks across legacy Remote I/O (RIO) links. Designed for 24V DC operation, the 1794-ASB /D series D adapter accommodates up to eight discrete or analog I/O modules, making it essential for expanding system I/O capacity in manufacturing, process control, and facility automation applications.
Key Features
- 8-Module Capacity: Accommodates up to 8 I/O modules, enabling the expansion of I/O capacity as needed
- Multiple Addressing Modes: Allows for standard, compact, complementary, standard-32, and complementary-32 addressing modes, making it highly versatile for different configurations
- Flexible Communication Rates: Supports 57.6 Kbps, 115.2 Kbps, and 230.4 Kbps communication rates
- Diagnostic Indicators: Features power on (green), adapter active (green), adapter fault (red), and local fault (red) diagnostic indicators
- DIN Rail Mounting: DIN rail mounted device with one Remote I/O (RIO) communication port for connecting Flex I/O rack to RIO capable controllers
Technical Specifications
The 1794-ASB /D operates on nominal 24V DC power with input voltage tolerance of 19.2 to 31.2 VDC. Power consumption is 330mA with maximum power dissipation of 4.6 Watts at 31.2 Volts DC and thermal dissipation of 15.7 BTU/hour at 31.2 Volts DC. The adapter features Flexbus output current of 640 milliAmps and isolation voltage between user power and Flexbus of 500 Volts AC. Operating temperature range is 0 to 55 degrees Celsius (32 to 131 degrees Fahrenheit). Physical dimensions are approximately 4 x 2 x 4 inches with weight of 6 ounces.
Typical Applications
The 1794-ASB /D is deployed in legacy and modernized control environments where distributed I/O architecture is required: production machinery control, material handling systems, HVAC equipment automation, water/wastewater treatment, refrigeration systems, metal fabrication, and chemical processes. Its broad controller compatibility and configurable addressing make it suitable for both retrofit projects and new installations that leverage existing RIO infrastructure.
Compatibility & Replacements
Compatible With
- Allen-Bradley Legacy controllers such as PLC2, PLC3 and PLC5 controllers as well as SLC500 automation platforms
- Modern Logix controller platforms as well as with 3rd party devices and encompass partner modules
- Remote I/O (RIO) communication networks using Belden 9463 or equivalent cables
- FLEX I/O 1794 discrete and analog I/O modules (up to 8 modules per adapter)
- Block Transfer Read (BTR) and Block Transfer Write (BTW) instruction sets
Replaces / Drop-In Replacement For
- 1794-ASB Series A, B, C modules (backward compatible with earlier series)
- Legacy FLEX I/O RIO adapter requirements in existing systems
- Custom RIO adapter solutions requiring 8-module capacity and distributed I/O
Works With
- RSLogix 5 (PLC-5 programming)
- RSLogix 500 (SLC-500 programming)
- RSLogix 5000 / Studio 5000 (Logix platform programming)
- Remote I/O (RIO) protocol communication
- FLEX I/O distributed I/O architecture
- 1793 Integra analog modules (Series D and later)
