Allen-Bradley 2002-NX70-HSC4 High-Speed Counter Module

The Allen-Bradley 2002-NX70-HSC4 is a high‑speed counter module designed for use with the PLC‑5 or SLC 500 series programmable controllers. It provides four independent counter channels, each capable of counting pulses up to 100 kHz. The module accepts 5V or 24V differential or single‑ended encoder inputs and supports quadrature (A/B) mode, up/down count, and frequency measurement. Each channel includes a programmable gate and reset input. The HSC4 module is typically used for position feedback, flow metering, and high‑speed batch counting in legacy automation systems.

Technical Specifications

• Model: 2002-NX70-HSC4

• Number of Counters: 4, independent

• Maximum Input Frequency: 100 kHz

• Input Types: Single‑ended (5V or 24V), differential (RS‑422)

• Input Modes: Up/down count, quadrature encoder (×1, ×2, ×4), direction plus pulse

• Counter Resolution: 32‑bit (0 to 4,294,967,295)

• Gate Inputs: 4 (one per channel, programmable active high/low)

• Reset Inputs: 4 (soft or hard reset)

• Outputs: None (counter values read via backplane)

• Power Supply: 5V DC from backplane (0.5A max)

• Compatibility: PLC‑5 family (1771 rack) or SLC 500 (1746 rack, with adapter)

• Operating Temperature: 0°C to 60°C

• Dimensions: Single slot module (1771 size)

Functional Description

The HSC4 module reads pulse signals from encoders, flow meters, or other high‑speed sources. The counter values are stored in the module’s internal registers and can be read by the PLC's ladder logic through block transfers (BTR/BTW). Each channel can be configured for counting up to a preset value, generating an interrupt when the preset is reached. The module also supports rollover and reset via software or external input. Configuration is done by writing a configuration word to the module.

Installation and Wiring

The module plugs into a 1771 I/O rack (PLC‑5) or a 1746 chassis (SLC 500 with appropriate adapter). Wiring is via a removable terminal block (36 pins). Shielded twisted‑pair cable is recommended for encoder inputs. Connect the shield to the module’s ground terminal. For differential inputs, connect A+, A‑, B+, B‑, Z+, Z‑. For single‑ended, connect signal and ground.

Typical Applications

This module is used for position measurement on machine slides, motor speed feedback, length measurement in cutting machines, and part counting in high‑speed assembly.

Conclusion

The Allen-Bradley 2002-NX70-HSC4 provides precise high‑speed counting for legacy PLC systems, offering a reliable interface for encoder and pulse signals.