Allen-Bradley 1745-LP104 SLC 100 Controller Unit

The Allen-Bradley 1745-LP104, also cataloged as the 1745-LP104 Programmable Controller Processor Unit, operates as a dedicated hardware component for direct CPU execution and discrete signal processing within SLC 100 platforms.

Hardware Specifications

Backplane Bus Interconnect & I/O Density Scaling

• Determinism & Bus Execution: The 1745-LP104 integrates directly with downstream SLC 100/150 expansion modules over a parallel expansion ribbon cable, updating CPU scan memory tables across 16 local and extended I/O channels without network protocol latencies.
• Firmware Flash Compatibility & Addressing: Internal memory register maps assign discrete input and output points directly to the processor memory table, maintaining rigid deterministic cycle execution across all system points.
• Galvanic Isolation & Field Protection: Optoisolated 24 VAC/DC digital inputs and isolated hard contact relay outputs isolate internal CPU logic gates from field ground loops and voltage transients.

Frequently Asked Questions

Q: Can expansion modules be plugged into or removed from the 1745-LP104 controller while under power?

A: No. Hot-swapping is strictly prohibited. Operating 18-30 VDC supply power must be de-energized prior to connecting or disconnecting the expansion bus ribbon cable to prevent damage to backplane driver circuits.

Q: What power source is required to operate the primary 1745-LP104 controller logic?

A: The main unit requires an external 18-30 VDC power supply connected directly to the dedicated supply input terminals.

Field Installation Guidelines

• Physical Mounting & Thermal Clearance: Mount the unit securely on an enclosure backpanel using standard mounting hardware. Maintain a minimum vertical clearance of 50 mm (2 inches) above and below the chassis to facilitate natural thermal convection.
• Supply Power & Field Terminal Wiring: Route 18-30 VDC power and I/O field cabling through separate wireways. Secure all conductors into screw terminal connections following standard industrial torque limits.
• Grounding & Noise Mitigation: Connect a dedicated low-impedance copper jumper from the unit chassis ground stud directly to the central cabinet earth ground bar. Separate low-voltage input conductors from high-voltage AC output wiring by at least 200 mm to suppress inductive noise coupling.