Allen-Bradley 1791-0B32: High-Density DC Output Block

Control numerous DC devices from a compact remote station. The Allen-Bradley 1791-0B32 delivers thirty-two DC output channels in a single Block I/O module. It provides reliable 10-30V DC switching for solenoids, indicators, and relays. This module is designed for distributed control applications with Allen-Bradley's classic PLC families.

Detailed Technical Specifications

• Product Model: Allen-Bradley 1791-0B32 (1791 Block I/O Series).
• Output Configuration: 32 DC sinking output channels.
• Voltage & Current: 10-30V DC, 0.5A per point (Vertical mount @ 60°C).
• Power Requirements: 19.2-30V DC external power, 300 mA typical current.
• Switching Speed: Fast response: ≤0.5 ms turn-on, ≤1.0 ms turn-off delay.
• Thermal Rating: Maximum power dissipation 19.2W (65.5 BTU/hr).
• Mounting Derating: Horizontal mounting reduces current to 0.25A per point at 60°C.
• Internal Protection: Module includes internal fusing for circuit protection.

Installation & Wiring Information

• Preferred Mounting: Vertical mounting is recommended for optimal heat dissipation and full current rating.
• Wiring: Use 14 AWG (2.0 mm²) solid wire with max 3/64" insulation on removable terminal strips.
• Configuration Switches: Two sets of DIP switches for setting I/O group, rack number, baud rate, and fault mode.
• Status Indicators: Includes COMM, STATUS, and 16 I/O status LEDs for easy monitoring and troubleshooting.
• Module Weight: 1.75 lbs (0.79 kg).
• Communication: Universal Remote I/O protocol for distributed network communication.

Packaging & Support Details

• Package includes one 1791-0B32 DC output module with identification labels.
• This product is supplied for maintaining existing legacy control systems.
• We ship globally using reliable carriers like FedEx, UPS, and DHL.

Expert FAQs

• What is the main application for this module in modern contexts?
  It serves as a critical spare part for maintaining aging but operational machines in industries like packaging, material handling, and automotive that still use PLC-5 or SLC 500 controllers on Remote I/O networks.
• Why does the current rating change so significantly with mounting orientation?
  Heat buildup. The components' ability to dissipate heat is much better in vertical orientation due to natural convection airflow. Horizontal mounting traps heat, requiring a 50% derating to prevent thermal damage.
• Can I connect a PLC input directly to this output?
  Yes, if the PLC input is a sinking type (common for 24V DC inputs). This module's sinking output will provide a path to ground to activate the PLC's input when energized.
• How do I configure the module's address on the Remote I/O network?
  Use the two banks of DIP switches on the module. One sets the "starting group" and rack number, the other sets the communication rate and fault response (like "last state"). You must match these settings to the configuration in the PLC program.
• What happens if an output is short-circuited?
  The internal fuse for that circuit should blow, protecting the module. The module has individual fusing. You would need to replace the entire module or seek repair if a fuse blows, as they are typically not user-serviceable.

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