Allen‑Bradley 1794‑ASB Universal Remote I/O 1794‑ASB

1. What it is

1794‑ASB is an Allen‑Bradley Flex I/O Remote I/O (RIO) adapter module.
It connects a Flex I/O “island” (up to 8 modules) to a Universal Remote I/O network from a PLC‑5, SLC 500, or (via bridge) a Logix controller.excellentplc.com+1

Typical use:

• Build a distributed remote I/O station using Flex I/O
• Connect that station back to the controller over a traditional AB RIO coax link (Belden 9463 or equiv.)cxzdhsb.com

2. Key specifications (typical)

Note: Some third‑party sites list slightly different temperatures, dimensions, or features; for critical design, always cross‑check with the official Rockwell installation instructions.

3. Main functions & features

• Remote I/O interface
  One RIO port; connects the Flex I/O rack to an RIO scanner port on PLC‑5 / SLC 500 or via 1756‑DHRI0 bridge to ControlLogix.jdzj.com+1
• Block transfer communication
  Uses BTR / BTW (Block Transfer Read / Write) instructions to move I/O data between controller and Flex I/O modules.cxzdhsb.com+1
• Integrated backplane power
  Built‑in power supply converts 24 VDC to 5 VDC for the Flex I/O bus and up to 8 modules; no separate backplane power module needed on that node.cxzdhsb.com
• Compatibility
  Designed for AB legacy controllers: PLC‑2, PLC‑3, PLC‑5 and SLC 500 RIO scanners.jdzj.com+1
  Also usable with modern Logix platforms and some third‑party equipment via RIO bridge or partner modules.jdzj.com+1
• Status LEDs
  • Power
  • Adapter activity
  • Adapter fault
  • Local faultjdzj.com+1
• Open‑style enclosure
  Must be installed in a proper industrial enclosure; not standalone in the plant.jdzj.com+1

4. Typical applications

• Distributed remote I/O for PLC‑5 / SLC 500
  Place Flex I/O modules near the machine and connect back to the PLC over RIO coax instead of running many multi‑core cables.rsdcsmro.com+1
• Retrofit / expansion of existing RIO networks
  Add or migrate remote I/O points without replacing the main PLC or RIO infrastructure; 1794‑ASB acts as the “drop” for a Flex I/O island.rsdcsmro.com+1
• Process & machine control
  Machine control, conveyor lines, motor control centers, process skids, etc., where you want compact, distributed I/O on a proven RIO network.rsdcsmro.com+1

5. Related Flex I/O adapters (for comparison)

6. Installation & setup highlights

1. Power & wiring
   • Supply 24 VDC (19.2–31.2 V) to the adapter; this feeds both the adapter electronics and the Flex I/O backplane.
   • Use Belden 9463 or equivalent RIO coax; follow AB’s wiring practices and grounding guidelines.cxzdhsb.com
2. RIO node address
   • Set the station address (e.g., via switches or software) so it is unique on the RIO network and matches the scanner configuration.11467.com
3. Flex I/O configuration
   • Install up to 8 Flex I/O modules on the same DIN rail.
   • In the controller (RSLogix 5/500), configure the 1794‑ASB and its I/O modules, then map I/O addresses using BTR/BTW.xydcontrols.com
4. Diagnostics
   • Use the LEDs to quickly see if the adapter has power, is communicating, or has a fault.
   • For deeper issues, check RIO coax, termination, and node address; refer to the controller’s fault codes and the 1794‑ASB installation instructions.jdzj.com+1

If you tell me your controller platform (PLC‑5, SLC 500, ControlLogix, CompactLogix) and what you’re trying to do (new project, retrofit, expansion), I can outline a more concrete configuration example for 1794‑ASB.