Allen Bradley 1745-LP103 Controller Unit

The Allen-Bradley 1745-LP103, also cataloged as the 1745-LP103 Processor Unit, operates as a dedicated hardware component for integrated logic execution and discrete signal processing within SLC 100 platforms.

Hardware Specifications

Backplane Bus Interconnect & I/O Density Scaling

• Determinism & CPU Scan Execution: The internal central processor executes user ladder logic directly against 10 selectable AC input channels and 6 hard contact output circuits while updating local expansion chassis racks across the ribbon backplane bus without network latency.
• Firmware Flash Compatibility & Address Mapping: Internal memory registers map input and output bit positions directly into the core processor image table, maintaining deterministic execution timing across expanded I/O channels.
• Galvanic Isolation & Field Noise Suppression: Optoisolated input stages and electromechanical output contacts isolate internal CPU logic gates from high-voltage field line surges and industrial electrical transients.

Frequently Asked Questions

Q: Can expansion ribbon bus connections be inserted or removed while the 1745-LP103 unit is powered?

A: No. Hot-swapping is prohibited. Master AC supply power to the processor chassis must be de-energized prior to connecting or disconnecting the expansion bus cable to avoid backplane component damage.

Q: How is the memory address space structured for the 1745-LP103 user program?

A: The onboard memory capacity consists of 885 words allocated for user ladder logic routines, internal control relays, counters, timers, and processor status flags.

Field Installation Guidelines

• Physical Mounting & Thermal Clearance: Securely mount the chassis vertically inside a metallic control enclosure using standard fasteners. Maintain a minimum vertical clearance of 50 mm (2 inches) above and below the housing to facilitate natural thermal convection.
• AC Input Power & Signal Wiring: Route incoming 85-132 VAC or 170-265 VAC line voltage through dedicated conduits. Tighten screw terminal connections to standard industrial torque specifications.
• Grounding & Noise Mitigation: Attach a low-impedance copper ground wire directly from the chassis grounding lug to the central enclosure earth ground bus. Separate low-voltage input control lines from high-current motor drive wiring by at least 200 mm to suppress inductive noise coupling.