Allen-Bradley POINT I/O 1734-MB Standard Mounting Base

Module Overview

The 1734-MB is the foundational structural component of the Allen-Bradley POINT I/O system. It serves as the physical housing and backplane interface for all 1734 series I/O modules. This mounting base is designed to snap directly onto a standard DIN rail, providing the electrical "bus" connections that allow data and power to flow between the communication adapter and individual I/O points. By utilizing a modular design, the 1734-MB allows for rapid assembly and expansion of distributed I/O systems, ensuring that modules are securely held and properly aligned within the rack.

Detailed Engineering Specifications

The 1734-MB is a passive component that facilitates the connection between the I/O module and the Removable Terminal Block (RTB).

• Product Type: I/O Mounting Base (Chassis Component)

• System Compatibility: All POINT I/O 1734 Modules

• Mounting Method: Horizontal or Vertical DIN rail (35mm)

• Bus Type: Integrated POINT I/O Backplane

• Number of Contacts: 8 Electrical contacts for module-to-backplane interface

• Module Alignment: Keyed mechanical placement to prevent incorrect module insertion

• Field Power Distribution: Integrated field-side power bus

• Installation Method: Snap-on DIN rail attachment with a locking screw for high-vibration security

• Terminal Block Compatibility: Requires a 1734-RTB or 1734-RTBS (sold separately)

• Physical Weight: 0.13 lbs (0.06 kg)

• Dimensions: Standard POINT I/O width (12mm)

Mechanical Design and Keying

One of the critical safety features of the 1734-MB is its integrated mechanical keying. Before inserting an I/O module, the user sets a rotary position on the mounting base that matches the specific module type (e.g., Digital Input, Analog Output, etc.). This ensures that once the base is wired, only a compatible module can be plugged in, preventing accidental hardware damage caused by mismatched voltage levels or signal types.

Backplane and Field Power Integration

The 1734-MB does more than just hold the module; it acts as a bridge for two distinct electrical paths:

• The POINTBus: The internal communication bus that carries data between the modules and the Ethernet or DeviceNet adapter.

• The Field Power Bus: A separate power distribution path that carries 24V DC or 120V AC to the I/O modules to power field-side devices like sensors and solenoids.

This dual-bus architecture allows for "Daisy Chaining" power across the entire I/O rack, significantly reducing the amount of individual power wiring required in the control cabinet.

Installation Best Practices

The 1734-MB should be installed starting from the left (next to the communication adapter) and moving to the right. Each base "interlocks" with the one to its left, creating a continuous backplane. Once the base is snapped onto the DIN rail, the orange locking screw at the bottom should be tightened to ensure the base remains stationary during module insertion or machine vibration.

Technical FAQ

Does the 1734-MB include the wiring terminals?

No. The 1734-MB is the base housing only. You must also purchase a Removable Terminal Block, such as the 1734-RTB (screw terminals) or 1734-RTBS (spring-clamp terminals), to connect your field wiring.

Can I replace a 1734-MB in the middle of a rack without moving other modules?

Because the mounting bases interlock horizontally to form the backplane, replacing a base usually requires sliding adjacent modules or bases to the side to disengage the internal bus connectors.

Is there a limit to how many 1734-MB bases I can connect together?

The physical limit is typically determined by the communication adapter (e.g., a 1734-AENTR supports up to 63 modules) and the power budget of your 1734-EP24DC expansion power supplies.