Allen Bradley 1734-VHSC High Speed Counter Modules

The Allen-Bradley 1734-VHSC, also cataloged as the 1734-VHSC Very High Speed Counter Module, operates as a dedicated hardware component for high-frequency pulse counting and encoder signal processing within Allen-Bradley POINT I/O systems.

Hardware Specifications

Deterministic Backplane Communication and I/O Density Scaling

• Backplane Bus Velocity: Interfaces with the POINT I/O backplane via a high-speed serial bus, delivering real-time pulse registration and frequency evaluation to the primary controller without network transmission delays.
• I/O Density Scaling: Constructed in a 12 mm narrow module profile to allow maximum channel density per linear DIN-rail distance, scaling system expansion inside control enclosures.
• EtherNet/IP Determinism: Direct mapping of counter accumulators, rate values, and operational flags to controller tags over EtherNet/IP adapter modules with Requested Packet Interval (RPI) configurable down to 1.0 ms.
• Firmware Flash Compatibility: Supports backplane firmware flash operations to verify consistent execution routines and operational parity across system controller upgrades.

Frequently Asked Questions

Q: Can the 1734-VHSC module be inserted or removed under power (RIUP)?

A: Hot-swapping is permitted only when backplane power is isolated or when operating in non-hazardous location class environments. Physical keying on the terminal base must be set correctly prior to module insertion.

Q: What is the mechanical function of the CHAS GND and C terminals on the terminal base?

A: The CHAS GND terminal connects directly to the mounting DIN rail to establish a high-frequency noise grounding path for shielded encoder cabling, whereas the C terminal provides a direct return path for DC sensor supplies.

Q: What input threshold options are hardware supported by the 1734-VHSC?

A: The module accepts differential and single-ended encoder or counter pulse signals operating across standard logic levels of 5 VDC, 12 VDC, and 24 VDC.

Field Installation Guidelines

• Secure the two-module terminal base onto a standard 35 mm DIN rail, verifying that the lower mounting latch locks completely into position.
• Route shielded signal cables for high-speed counter inputs away from high-voltage AC lines. Terminate cable shields directly at the CHAS GND terminal on the base assembly.
• Verify that terminal wiring configuration and external power supply selections match the intended operating voltage range (5 VDC, 12 VDC, or 24 VDC) prior to energizing the backplane bus.
• Tighten terminal block screws to the specified torque rating of 0.5 to 0.6 Nm to ensure gas-tight electrical contact and vibration resistance.