HITACHI LYD000A

HITACHI LYD000A

Product Introduction LYD000A is a controller circuit board manufactured by Hitachi of Japan for Hitachi H-series PLC and process control rack systems. The board carries a Hitachi dedicated processor, executing equipment control logic and data communication, connecting to I/O modules over a backplane bus. It is used for rack-based control of industrial machinery, production lines, and dedicated equipment; it is a discontinued spare replacement for installed systems.

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Description

HITACHI LYD000A

Technical Specifications

  • Product type: CPU control board
  • Processor: Hitachi 32-bit dedicated CPU
  • Memory: On-board SRAM and EPROM firmware
  • Bus: Hitachi system dedicated backplane
  • Communication: RS232 programming port
  • Supply: Rack backplane DC5V
  • Temperature: 0 °C to +60 °C
  • Storage: -20 °C to +70 °C
  • Humidity: 5 % to 95 %, non-condensing
  • Protection: IP20
  • Installation: Eurocard plug-in
  • Watchdog: Hardware watchdog

Functional Features

  • Executes equipment control logic programs
  • Reads and writes I/O modules over backplane
  • RS232 port for program upload/download
  • On-board EPROM firmware, SRAM runtime data
  • Hardware watchdog with automatic reset on program runaway
  • Power-up self-diagnostics of CPU, memory, bus
  • Front panel LEDs for power, run, fault
  • Fault event logging
  • Interrupt processing
  • Industrial-grade long-term reliability

Application Scenarios

  • Hitachi PLC rack control unit
  • Packaging and printing machine main CPU
  • Production line dedicated equipment control
  • Legacy equipment spare replacement
  • Industrial machinery original cabinet CPU

Materials and Construction

  • PCB: FR4 multilayer board
  • Core: Hitachi CPU, EPROM, SRAM
  • Communication: RS232 transceiver
  • Connector: Gold-plated Eurocard connector
  • Passive components: Tantalum capacitors, metal film resistors, crystal
  • Front panel: Metal panel with LED windows

Structural Features

  • Eurocard plug-in in Hitachi rack slots
  • Front panel LEDs and RS232 port
  • Board partitions between processor, memory, communication
  • Backplane gold fingers
  • Vibration-hardened board
  • Metal panel shielding

Working Principle Backplane DC5V powers the board; the CPU runs self-diagnostics and loads the control program from EPROM into SRAM for execution. It periodically reads input modules over the backplane, runs control logic, and drives output modules to field actuators. The RS232 port connects a programmer for program transfer. The watchdog monitors CPU execution and resets on abnormal operation. Fault events are stored in non-volatile memory.

Installation Requirements

  • Insert into CPU slot with power off and ESD protection
  • Shielded RS232 serial cable
  • Rack grounding
  • Cabinet temperature 0 °C to +60 °C
  • After power-up confirm I/O configuration matches program
  • Store spares in anti-static packaging

Precautions

  • Do not hot-swap during online operation
  • Reload control program after CPU replacement
  • Replace backup battery periodically to prevent SRAM data loss
  • Wear ESD wrist strap
  • Store spares in anti-static moisture-proof packaging
  • Use front panel LEDs to diagnose faults

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