Product Overview

The Allen-Bradley 1785-MS operates as a plug-in volatile RAM expansion memory module designed specifically for the classic PLC-5 programmable logic controller platform, including the PLC-5/15 Series B architecture. This hardware cartridge expands the native memory workspace of the processor by adding 8 Kwords of active Static RAM (SRAM). By sliding this module directly into the integrated memory slot on the face of the PLC CPU, engineers can expand a standard 6K word base system up to a total workspace of 14K words. This additional capacity allows the controller to execute larger bit-logic rungs, store deeper data tables, and process complex mathematical instruction sets required by expanding factory production lines. We offer this component exclusively as a 100% brand new, original factory unit to ensure precise pin alignment and seamless hardware synchronization.

Technical Specifications

The following engineering table highlights the structural dimensions, capacity ratings, and electrical performance criteria for the 1785-MS memory expansion cartridge:

Engineering Advantages

• Instant Volatile Capacity Scaling: The cartridge instantly expands the processor active memory boundary without requiring costly processor upgrades or complete rack rebuilds. It resolves memory-limit faults (CPU overflows) immediately when adding new I/O racks or remote DH+ nodes to a legacy automation loop.

• Zero-Latency Logic Execution: Because the 1785-MS utilizes high-speed SRAM chips rather than slower non-volatile memory architectures, the host processor maintains its optimal 2 ms per Kword bit-logic program scan time. It introduces no operational buffering delays, which preserves fast execution of time-critical machine interlocks.

• Hardware Jumper Write Protection: The module features an integrated physical hardware jumper that toggles a hard-wired write-protection circuit. This protection prevents unauthorized network downloads, accidental remote software modifications, or bit overwrites from uncalibrated human-machine interfaces (HMIs).

• Direct Faceplate Integration: The compact card slides effortlessly into the front-loading memory expansion slot located on the primary faceplate of the PLC-5 processor. This localized layout eliminates the need to strip down the 1771 universal chassis backplane or disconnect field-side wiring arms during memory upgrades.

• Ruggedized Contact Pins: Gold-plated mating pins line the connection interface of the module to resist oxidation and surface corrosion inside hot, humid factory enclosures. This robust connection architecture prevents intermittent connection drops induced by heavy machinery vibrations and continuous physical line movement.

FAQs

• Does the 1785-MS memory module retain the stored automation program if I remove it from the PLC-5 processor faceplate?

  No. The 1785-MS utilizes volatile Static RAM (SRAM) architecture, which means it requires constant electrical bias to preserve bit configurations. If you extract the module from the host processor slot while unpowered, or if the main 1770-XY chassis battery drains completely, the card loses its data registers instantly.

• What specific installation procedure must I follow to prevent program loss during the upgrade?

  You must power off the 1771 I/O chassis completely before inserting the 1785-MS cartridge into the CPU slot to avoid electrical arcing or component damage. Ensure that a fresh 1770-XY lithium backup battery remains installed in the processor to maintain the existing base program memory while the main rack power is off.

• Can I utilize the 1785-MS card inside newer Enhanced PLC-5 controllers like the 1785-L20 or 1785-L40?

  No. The 1785-MS is engineered primarily for Classic PLC-5 platforms like the 1785-LT (PLC-5/15) Series B units. Newer Enhanced or ControlNet PLC-5 processors feature different physical memory architectures and instead utilize higher-capacity non-volatile EEPROM expansion cartridges, such as the 1785-ME32 or 1785-M100.