Allen-Bradley 1785-V80B VME/PLC-5 Programmable Controller Module

The 1785-V80B is an Allen-Bradley PLC-5 processor module designed for VMEbus integration, combining traditional PLC-5 control execution with open VMEbus backplane architecture. Equipped with 100K words of SRAM user memory, it provides processing capability and multi-node network connectivity for complex, high-speed industrial control and data acquisition systems.

VMEbus Integration & Architecture

As a VMEbus-compatible processor, the 1785-V80B mounts into standard VME chassis to facilitate high-speed data transfer across the VME backplane. It serves as either a VME system controller or standard VME board node, allowing direct memory mapping and peer-to-peer data interchange between PLC logic, VME single-board computers (SBCs), and specialized third-party co-processors.

Memory & Serial Communications

The card features 100K words of battery-backed SRAM for user program logic, data tables, and system variables. Front-panel communication interfaces include an RS-232-C serial port configured for ASCII, DF1 point-to-point, or DF1 radio modem protocols, supporting programming terminals, operator interfaces, and SCADA connectivity.

Technical Specifications

Installation & Power Guidelines

Before inserting or removing the processor from the VME enclosure, ensure that system rack power is fully de-energized to prevent edge connector arc damage. Verify that onboard VME backplane jumpers—such as system controller enable, interrupt request levels, and VME base address switches—are properly set before applying 5 VDC system power.

Frequently Asked Questions

Q: What bus architecture is the 1785-V80B processor designed for? A: The 1785-V80B is built specifically for 6U VMEbus chassis and backplanes, combining VME system access with Allen-Bradley PLC-5 execution logic.

Q: How is user memory retained in the 1785-V80B when system power is disconnected? A: The module relies on an onboard lithium battery to preserve its 100K words of static RAM (SRAM) data and program memory during power-down cycles.

Q: What protocols does the onboard RS-232-C serial port support? A: The RS-232-C channel supports DF1 full-duplex, DF1 half-duplex, DF1 radio modem, ASCII communication, and DH-485 protocol conversion for programming and operator interface access.