Allen-Bradley 1771-VHSC Very High Speed Counter Module

The Allen-Bradley 1771-VHSC is a Very High-Speed Counter Module specifically designed for applications that require precise high-speed counting, such as motion control and industrial process monitoring. This module offers four configurable counters, allowing users to handle rapid counting tasks effectively. It supports multiple counting modes, including single-phase, quadrature, and rate/period measurement, providing flexibility for various control needs.

Advantages:

• Configurable for different counting modes, including encoder and rate measurements.

• Capable of handling high input frequencies up to 1 MHz for single-channel counting.

• Equipped with eight isolated outputs for flexible system integration and advanced output control.

General Info

• Manufacturer: Allen-Bradley

• Model Number: 1771-VHSC

• Type: Very High-Speed Counter Module

• Number of Counters: 4

• Location: 1771 Series A or B VD chassis

• Maximum Coin Value: 0-999,999 (programmable)

• Typical Processing Time: 1.5 to 29 ms

• Maximum Input Frequency: 1 MHz for single-channel counting

Features

• Multiple Counting Modes: The 1771-VHSC supports various counting modes, including single-phase counting, quadrature encoder inputs, and rate/period measurements. It is suitable for applications that demand fast and accurate counting.

• High-Speed Performance: The module offers high-speed counting capabilities, with input frequencies up to 1 MHz in single-channel mode, 250 kHz in quadrature encoder mode, and 500 kHz in rate/measurement modes.

• Flexible Inputs and Outputs: The module has 4 counters, each with 9 inputs (A, B, gate/reset input). There are also 8 assignable outputs with high-speed switching and customizable preset values for each counter.

• Advanced Isolation and Protection: The module provides electrical isolation between inputs, outputs, and backplane, ensuring robust and safe operation in challenging industrial environments. The isolation voltage is 1500V between the input, output, and backplane, and 300V between isolated channels.

Technical Specifications

• Number of Counters: 4

• Location: 1771 Series A or B VD chassis

• Maximum Count Value: 0 to 999,999 (programmable)

• Typical Processing Time: 1.5 to 29 ms

• Worst Case Processing Time:

  • Binary: 5.5 ms

  • BCD: 11 ms (on configuration change)

• Maximum Input Frequency:

  • Swell Bounce: 100 Hz (electromechanical switch)

  • Encoder Modes (2-channel quadrature): 250 kHz

  • Rate/Measurement and Continuous Rate Modes: 500 kHz

  • Counter Modes (single channel): 1 MHz

• Inputs per Counter: 9 (A, B, gate/reset input)

• Input Voltage: 5V or 12-24V (user selectable)

• Input Current:

  • Typical at 5V: 7 mA

  • 12-24V: 7 to 15 mA

  • Minimum: 4 mA

• Number of Outputs: 8

• Maximum Output Off-State Leakage Current: < 10 μA at 24V DC

• Maximum On-State Voltage Drop: 0.05Ω per output

• Output Control: Assignable to any of the 4 counter channels; each output can have a 'turn-on' and 'turn-off' preset value

• Output Voltage: 5 to 24V DC (customer supplied)

• Output Current: 2A per channel (all outputs can be active simultaneously without derating)

• Output Switching Time:

  • Turn-On: < 10 μs

  • Turn-Off (Typical): 30 μs

• Filtering: Selectable — High-speed or filtered (< 100 Hz)

• Isolation Voltage:

  • Input to Backplane: 1500V

  • Output to Backplane: 1500V

  • Between Isolated Channels: 300V

• Power Dissipation:

  • Maximum: 13 Watts

  • Minimum: 2 Watts

• Thermal Dissipation:

  • Maximum: 54.2 BTU/hr

  • Minimum: 6.8 BTU/hr

• Conductors: Belden 9182 or equivalent Category 2.1; 750 foot Belden 9182 or equivalent Category 1.0

• Fuse: 7AG 3A fuse — Littelfuse 225003

• Environmental Conditions:

  • Operating Temperature: 0 to 60°C (32 to 140°F)

  • Storage Temperature: -40 to 85°C (-40 to 185°F)

  • Relative Humidity: 5% to 95% (without condensation)

• Keying Field Wiring Arm Screw Torque: 24-28 inch-pounds; 28-30 inch-pounds

• Terminal Block: 40-terminal, Cat. No. 1771-WN

Compliance and Certifications

• Certifications: UL Listed, CE Marked

• Safety Standards:

  • EN 61131-2: Compliance for programmable controller equipment

  • EMC Compliance: Meets EN 50081-2 and EN 50082-2 standards