Allen-Bradley 1745-E157 SLC 150 I/O Expansion Unit

Configured for discrete signal expansion and contact execution in SLC 150 programmable logic controller platforms, the Allen-Bradley 1745-E157 (1745-E157 I/O Expansion Unit) provides direct physical/electrical execution across hardwired field terminal points.

Hardware Specifications

Backplane Bus Interconnect & I/O Density Scaling

• Determinism & Bus Execution: The 1745-E157 expansion unit links directly to the primary SLC 150 base unit via a multi-conductor ribbon interconnect cable, allowing the CPU scan loop to update field state points without protocol translation latencies.
• Firmware Flash Compatibility & Address Mapping: Dedicated registers map directly into the base controller image table, maintaining deterministic execution timing across expanded I/O banks.
• Galvanic Isolation & Noise Immunity: Optoisolated input stages and isolated output channels protect backplane logic drivers from transient spikes and ground loops in industrial environments.

Frequently Asked Questions

Q: Can the 1745-E157 expansion chassis be hot-swapped while the SLC 150 controller is operating?

A: No. Hot-swapping is prohibited. Main power supply to the controller base and expansion modules must be de-energized prior to connecting or removing the expansion ribbon bus cable.

Q: How is backplane power delivered to the internal logic components of the 1745-E157?

A: Logic operating power and control bus communication signals pass through the dedicated expansion ribbon cable connected directly to the primary SLC 150 base unit.

Field Installation Guidelines

• Physical Mounting & Airflow Clearance: Securely mount the chassis to the enclosure backpanel using standard mounting hardware. Maintain a minimum vertical distance of 50 mm (2 inches) above and below the enclosure to ensure proper natural thermal convection.
• Ribbon Interconnect Cabling: Fully insert and latch the expansion ribbon cable into the dedicated headers on both the primary processor and the 1745-E157 unit before energizing the system power circuit.
• Grounding & Cable Separation: Connect a dedicated grounding wire from the chassis frame terminal directly to the cabinet single-point earth ground bar. Separate low-voltage DC lines from high-voltage AC lines by at least 200 mm to mitigate inductive noise coupling.