Description
The Allen Bradley 1794-ASB is a high-performance Remote I/O (RIO) Adapter for the Flex I/O system. It acts as a communication gateway, allowing a central controller (such as a PLC-5 or SLC 500) to interface with up to eight Flex I/O modules over a standard Remote I/O network.
Product Parameters (Datasheet)
- Model Number: 1794-ASB
- Series: Flex I/O Communication Adapter
- Network Protocol: Allen-Bradley Remote I/O (RIO)
- I/O Capacity: Supports up to 8 Flex I/O modules
- Communication Rate: 57.6 Kbps, 115.2 Kbps, or 230.4 Kbps (Switch selectable)
- Input Voltage: 24V DC (Nominal)
- Input Voltage Range: 19.2V to 31.2V DC (includes 5% AC ripple)
- FlexBus Current: 640 mA maximum
- Isolation Voltage: 500V AC between network and logic/power
- Operational Temperature: 0°C to 55°C (32°F to 131°F)
Allen Bradley 1794-ASB
Allen Bradley 1794-ASB
Allen Bradley 1794-ASB
Country of Origin
The 1794-ASB was engineered and manufactured by Rockwell Automation / Allen-Bradley in the USA.
Application Fields
The 1794-ASB is a staple in distributed control architectures across various industries:
- Automotive Assembly: Connecting remote sensors and actuators on assembly lines to a central PLC.
- Material Handling: Managing conveyor systems and sorting stations across large warehouse footprints.
- Food & Beverage: Coordinating decentralized I/O for bottling and packaging machinery.
- Water Treatment: Monitoring remote lift stations and chemical dosing equipment.
- Mining & Metals: Interfacing with remote field instrumentation in harsh processing environments.
Product Usage Instructions
- Mounting: Snap the module onto a standard DIN rail or use the integrated mounting holes for panel mounting. It is typically the leftmost module in a Flex I/O bank.
- Addressing: Use the onboard DIP switches to set the Rack Address, Start Quarter, and I/O Grouping. Ensure the address does not conflict with other devices on the RIO link.
- Network Wiring: Connect the RIO link (Blue Hose) to the 3-pin connector. Use a 1/2-watt termination resistor (82 ohm or 150 ohm depending on baud rate) at both physical ends of the network.
- Power Connection: Connect a 24V DC power source to the module. Ensure the power supply is sized to handle both the adapter and the connected I/O modules.
- Configuration: Within the PLC programming software (e.g., RSLogix 5 or 500), configure the I/O rack for the specific modules attached to the 1794-ASB.
Product Technical Description
Technically, the 1794-ASB serves as a translator between the bit-serial Remote I/O network protocol and the parallel FlexBus. It continuously scans the attached I/O modules, packaging their data into RIO discrete or block transfer frames for the scanner. One of its key strengths is its modularity; it allows users to mix and match digital, analog, and specialty I/O on the same DIN rail. The adapter provides the necessary power to drive the internal logic of the attached modules through the FlexBus.
Q&A (Common Questions)
Q: Can I use the 1794-ASB on an Ethernet/IP network? A: No, the 1794-ASB is exclusively for the legacy “Blue Hose” Remote I/O network. For Ethernet/IP, you would need a 1794-AENT or 1794-AENTR adapter.
Q: What does the “COMM” LED flashing red indicate? A: A flashing red COMM LED typically indicates a communication timeout or a configuration mismatch between the PLC and the adapter. Check your DIP switch settings and the PLC scan list.
Q: How many modules can one 1794-ASB support? A: It can support up to 8 Flex I/O modules. However, you must ensure that the total current draw from the modules does not exceed the 640 mA limit of the FlexBus.
Q: Is the 1794-ASB hot-swappable? A: While Flex I/O modules can be removed and inserted under power (RIUP), it is best practice to power down the adapter when adding or removing modules to ensure the FlexBus re-initializes correctly.
Similar Model Recommendations
- Allen Bradley 1794-ASB2 (2-slot version for smaller applications)
- Allen Bradley 1794-ACN (ControlNet version)
- Allen Bradley 1794-ADN (DeviceNet version)
- Allen Bradley 1794-AENT (Ethernet/IP version)
- Allen Bradley 1794-IB16 (Commonly used 16-point digital input module)
For technical support or to request a quote for the Allen Bradley 1794-ASB, please contact our automation specialists today.
