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GE DS3820FEXB1A1A

Product Name:​ GE Fanuc Series 90-70 High-Speed Counter Module
Product Overview:​ The DS3820FEXB1A1A is a 4-channel high-speed counter function module designed by GE Fanuc for the Series 90-70 PLC system, dedicated to encoder signal acquisition, pulse counting, and speed measurement in high-speed signal processing scenarios.
Technical Specifications:
  • Channels: 4 independent high-speed counters
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Detailed content

  • Counting Frequency: Up to 1MHz per channel
  • Counter Bit Width: 32-bit signed integer
  • Counting Modes: Quadrature encoding (A/B phase), single pulse, direction + pulse
  • Input Signal Levels: 5VDC TTL compatible / 24VDC (with internal conversion)
  • Preset Value Range: -2,147,483,648 ~ +2,147,483,647
  • Comparison Function: Supports 4 independent comparison outputs
  • FIFO Buffer: 256 words depth per channel
  • Operating Temperature: -20°C ~ +60°C
  • Backplane Bus: Genius Bus / 90-70 series backplane
Functional Features:
  • 4 fully independent 32-bit high-speed counters
  • Supports quadrature encoding mode, simultaneously acquiring direction and speed information
  • Hardware FIFO buffering reduces CPU interrupt burden
  • 4 independent comparison registers supporting high-speed output triggering
  • Supports counting gating function for selective counting
Structural Features:​ Standard 90-70 series module form factor. Front-end configured with dedicated high-speed counter signal wiring terminals. Module top equipped with status diagnostic LED indicator group. Backplane gold-finger connection supports hot-swapping.
Material Composition:
  • Housing: Flame-retardant polycarbonate engineering plastic
  • Terminals: Phosphor bronze with tin plating
  • PCB: Multi-layer FR-4 board with signal integrity design
Working Principle:​ External encoder A/B phase signals are shaped by front-end signal conditioning circuits and sent to dedicated high-speed counting chips. The chip completes quadrature decoding and 32-bit accumulative counting at hardware level. Counting results are written to CPU data area via backplane bus using DMA method, while comparison registers perform hardware comparison with current count values to trigger outputs.
Application Scenarios:​ CNC machine tools, printing machinery, textile machinery, material conveying systems, robot joint control, elevator control.
Installation Requirements:
  • Install in GE Fanuc 90-70 series PLC rack (IC697CHS790, etc.)
  • Encoder signal lines must use shielded twisted pair cable, shield grounded at single point
  • Distance between module and encoder recommended not to exceed 15 meters (in high-speed mode)
  • Ensure adequate backplane power supply (backplane current requires additional calculation)
Usage Notes:
  • When counting frequency exceeds 500kHz, use shielded cable and shorten wiring distance
  • Quadrature encoder A/B phase wiring must not be reversed, otherwise counting direction will be wrong
  • Preset value modification must be completed through dedicated instructions in the program
  • All signal lines must be confirmed correctly connected before powering on the module

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