Allen Bradley 1745-E151 SLC 100 Expansion

onfigured for discrete signal expansion and relay drive interface in SLC 100/150 programmable logic controller platforms, the Allen-Bradley 1745-E151 (1745-E151 I/O Expansion Unit) provides direct physical/electrical execution across 32 hardwired field points.

Hardware Specifications

Backplane Bus Interconnect & I/O Density Scaling

• Determinism & Bus Execution: The 1745-E151 interface communicates directly with the master SLC 100 or SLC 150 controller base unit through a parallel interconnect cable, extending the internal logic scan across an additional 20 AC inputs and 12 output channels without requiring network protocol overhead.
• Firmware Flash Compatibility & Address Mapping: Hardware-addressed fixed register slots assign inputs 21 through 40 and outputs 113 through 124 in the internal controller memory map, enforcing strict hardware-level execution deterministic timing across all I/O channels.
• Proximity Isolation & Noise Immunity: Galvanic channel separation and optoisolated input stages mitigate electromagnetic cross-talk and transient noise common to high-density AC wiring conduits in industrial enclosures.

Frequently Asked Questions

Q: Can the 1745-E151 expansion unit be connected or disconnected while the controller is powered?

A: No. Hot-swapping is strictly prohibited. Master power to the primary SLC base unit and all expansion chassis must be isolated prior to connecting or disconnecting the ribbon bus cable to prevent damage to the backplane logic drivers.

Q: How is field input power sourced for the 85-132 VAC sinking circuits?

A: The AC input circuits require an external 120 VAC phase voltage supply connected across the field terminals. The internal optocouplers sink current from the external AC voltage line through the user-supplied field devices.

Field Installation Guidelines

• Physical Mounting & Clearance: Mount the unit securely on a standard panel surface using standard mounting hardware. Maintain a minimum vertical clearance of 50 mm (2 inches) above and below the enclosure to ensure unobstructed natural thermal convection across the internal heat sink structures.
• Ribbon Cable Interconnect: Ensure the multi-conductor expansion bus ribbon cable is locked into the designated header sockets on both the base controller and the expansion unit before applying supply voltage. Avoid sharp bend radii exceeding manufacturer tolerances.
• Grounding & Shielding: Connect a low-impedance copper ground conductor from the chassis ground terminal directly to the central enclosure ground bus bar. Ensure sensor and field wiring conduits are physically separated from high-voltage motor drive cabling by at least 200 mm to suppress inductive noise coupling.