The Allen-Bradley 1775-MED, also cataloged as the 1775MED Memory Module, operates as a dedicated hardware component for error-correcting RAM retention and logic execution within PLC-3 control system racks.

Model Catalog Architecture

• 1775: Bulletin 1775 PLC-3 system hardware family.
• MED: Error-correcting RAM memory module unit.
• 16-bit: Standard word length architecture for processor system addressing.
• RAM: Error-correcting random-access memory storage structure.

Technical Performance Parameters

Backplane Communications & System Microcode

The module interfaces directly with the central processing unit across the rack backplane bus, enabling deterministic memory access cycles at 450 ns speeds. Internal logic supports system microcode execution and maintains strict firmware flash compatibility across connected PLC processor cards, minimizing backplane latency during high-speed I/O scan routines.

Package Component List

• 1 x Allen-Bradley 1775-MED Memory Module
• 1 x Static Protective Packaging Sleeve

Rack Installation & Physical Handling Standards

• Power Interruption Protocol
  • Always disconnect system power from the main rack backplane before inserting or removing the memory card to prevent bus logic corruption.
• Electrostatic Discharge Protection
  • Ground all servicing tools and wear a grounded wrist strap before handling module edge connectors to preserve semiconductor logic.
• Card Guide Mechanical Alignment
  • Align the circuit card carefully with top and bottom rack guide rails, seating backplane connectors securely into the chassis socket.
• Chassis Thermal Management
  • Maintain unobstructed airflow across rack ventilation slots to ensure ambient temperatures remain within 0 to +60 deg C during active operation.

Technical FAQs

• What is the primary functional access time for the 1775-MED memory circuit?

  The memory array features an access speed of 450 ns for high-speed backplane data retrieval.

• What voltage is required to power the memory card logic?

  The card operates on a 5 VDC (+/-5%) power rail supplied directly through the chassis backplane bus.

• Can this memory module be inserted while the PLC rack is powered up?

  No, removing or inserting the card under backplane power can cause bus noise and memory memory corruption.

• What is the typical logic power dissipation of the circuit card?

  The module consumes approximately 2 W of continuous power during standard processing operations.

• How is error correction handled on the internal RAM array?

  Integrated error-correcting memory logic detects and corrects single-bit memory faults during active read-write operations.

• What thermal limits must be maintained inside the chassis panel?

  The operating environment surrounding the module must remain strictly within 0 to +60 deg C.

• What word size does the 1775-MED module support?

  The memory architecture uses a standardized 16-bit word length structure for addressing.

• How does the module interact with host processor microcode?

  The hardware maintains backplane timing alignment and firmware flash compatibility across host controller processors.