Introduction to the Allen-Bradley 1746-HSCE High Speed Counter
The Allen-Bradley 1746-HSCE High Speed Counter is a powerful module built for precision counting, encoder integration, and high-speed counters in PLC automation in industrial systems. As part of the SLC 500 I/O Modules, this module has long been a trusted solution for industries requiring accurate speed, motion, and length measurement. Despite being discontinued, the 1746-HSCE remains widely used in existing systems and sought after for its reliability and versatility.
In this article, we’ll take a deep dive into the specifications of the Allen-Bradley 1746-HSCE High Speed Counter, explain why these specifications matter, and provide real-world application examples to help engineers and automation professionals better understand its functionality.
Key Specifications of the Allen-Bradley 1746-HSCE High Speed Counter
The Allen-Bradley 1746-HSCE High Speed Counter is designed with industrial-grade performance in mind. Below are its detailed specifications and their importance.
Operating Temperature Range
The module operates between 0°C to +60°C (32°F to 140°F). This ensures the counter functions reliably within standard industrial environments. Exceeding this range can cause overheating or malfunction.
Storage Temperature Range
For non-operating conditions, the module tolerates -40°C to +85°C (-40°F to 185°F). This extended storage range is critical for shipping, warehousing, or spares inventory.
Humidity Tolerance
The module withstands 5% to 95% humidity, non-condensing. This means it’s designed to handle challenging plant conditions, provided moisture is controlled.
Backplane Current Consumption
The 1746-HSCE High Speed Counter draws 320 mA at +5V DC from the backplane and 0 mA at +24V DC. This figure is crucial for system designers to ensure the PLC chassis power supply can support the module.
Maximum Cable Length
The maximum supported encoder cable length is 305 meters (1000 feet). Long cable support is especially important in applications like conveyor systems, where encoders may be far from the PLC cabinet.
Agency Certifications
The module carries CSA certification, UL listing, and CE marking. These certifications guarantee compliance with safety and industrial standards.
Isolation Rating
The Allen-Bradley 1746-HSCE High Speed Counter features 1500V isolation between inputs and the backplane. This is essential for preventing noise, voltage spikes, and grounding issues.
Input Channels
The module supports quadrature encoder inputs (A, B, and Z channels) or up/down pulse counting. This flexibility makes it suitable for directional counting and position tracking.
Pulse and Frequency Handling
● Minimum Pulse Width: 10 microseconds
● Minimum Pulse Separation: 4.5 microseconds
● Maximum Input Frequency: Up to 50 kHz in sequencer/range mode, 32.767 kHz in rate mode
These specifications ensure that the Allen-Bradley 1746-HSCE High Speed Counter can handle high-frequency pulses from encoders or flow sensors.
Count Range
The counter has a 16-bit signed range (-32,767 to +32,767). This allows for detailed counting, though long-term accumulation may require overflow management in software.
Outputs
It features four open-collector sinking outputs, configurable for triggering based on count thresholds, ranges, or sequences. With adjustable voltage ranges (4.5–10V DC or 10–30V DC) and current limits (16mA–125mA), the outputs can drive relays, indicators, or intermediate devices.
Update and Response Times
● Update Cycle: ~4.8 ms
● Step Response: ~100 ms input latency, ~2.5 ms output reaction
This ensures quick but not instantaneous response, making the module more suitable for supervisory rather than ultra-fast closed-loop control.
Why These Specifications Matter
Each specification of the Allen-Bradley 1746-HSCE High Speed Counter has practical importance:
● Temperature and Humidity Tolerance: Allows deployment in demanding plant floors.
● Power Consumption: Ensures compatibility with PLC rack power capacity.
● Isolation Rating: Protects against noisy industrial environments.
● Maximum Cable Length: Provides flexibility in machine design and layout.
● Pulse Width and Frequency Specs: Define what types of encoders and sensors can be used.
● 16-bit Range: Important for applications needing precision but requires rollover handling in long-running operations.
● Outputs: Provide hardware-level control for faster reactions without CPU scan delays.
● Update Times: Define how quickly the system reacts to motion or speed changes.
Modes of Operation of the Allen-Bradley 1746-HSCE High Speed Counter
The module supports several operational modes to suit different applications:
1. Range Mode
Triggers outputs when the count falls within a preset range. Ideal for limit monitoring.
2. Rate Mode
Calculates speed or rate of pulses. Used for motor speed monitoring, conveyor belt velocity, or flow measurement.
3. Sequencer Mode
Follows specific pulse sequences to activate outputs. Useful in indexing and positioning applications.
These modes allow the module to act as more than just a counter—it becomes a smart control element.
Industrial Applications of the Allen-Bradley 1746-HSCE High Speed Counter
The Allen-Bradley 1746-HSCE High Speed Counter is widely used across industries. Below are examples:
Packaging Industry
Used in cut-to-length machines, where encoder pulses track material feed. The module counts pulses and activates a cutter at the exact length.
Conveyor Systems
Encoders provide pulses as items move along a conveyor. The counter monitors position and speed, activating diverters or stoppers.
Flow Measurement
In flow meters, pulses represent liquid or gas volume. The counter computes real-time flow rates for monitoring or batching.
Motor Speed Monitoring
The module, in rate mode, calculates RPM from encoder signals. This ensures motors operate within safe ranges.
Printing and Textile Machines
Used for precise registration and indexing, ensuring accuracy in print and fabric cutting.
Rotary Tables and Turrets
Tracks rotary position with quadrature encoders, enabling accurate positioning.
Safety Feedback Systems
Provides independent encoder monitoring to validate motion, adding redundancy in safety systems.
Advantages and Limitations of the Allen-Bradley 1746-HSCE High Speed Counter
Advantages
● Reliable pulse counting up to 50 kHz
● Flexible encoder input support
● Hardware-controlled outputs reduce CPU burden
● Long cable support for remote applications
● Widely compatible with SLC 500 systems
Limitations
● Discontinued product—new units may be hard to source
● 16-bit range requires overflow management
● Update cycle (~4.8 ms) too slow for high-speed closed-loop control
● Limited to one channel input compared to modern multi-channel counters
Migration and Lifecycle Considerations
Since the Allen-Bradley 1746-HSCE High Speed Counter is discontinued, engineers must plan for long-term system support. Options include:
● Stocking refurbished or surplus units
● Migrating to newer Rockwell Automation high-speed counter modules
● Re-engineering systems to ControlLogix or CompactLogix platforms with updated HSC capabilities
Conclusion: Maximizing Value from the 1746-HSCE
The Allen-Bradley 1746-HSCE High Speed Counter remains a reliable solution for high-speed counting, encoder interfacing, and motion tracking in industrial automation. Its combination of robust specifications, multiple operating modes, and long cable support made it a staple in packaging, material handling, and manufacturing systems. However, users must keep in mind its discontinued status and plan for replacements in the future.
For engineers maintaining existing SLC 500 systems, the 1746-HSCE continues to deliver reliable performance. If you’re interested in acquiring this module or compatible alternatives, consider exploring the Allen-Bradley 1746-HSCE High Speed Counter product page for availability and specifications.
Related Product Collections You Might Be Interested In
To complement the Allen-Bradley 1746-HSCE High Speed Counter, explore these related collections from Industrial Electrical Warehouse:
Discover a range of PLCs and automation modules designed for industrial applications. Ideal for integrating high-speed counters into your control system.
Industrial Electrical & Automation ➝
Browse a broad selection of industrial electrical and automation products that work hand-in-hand with control modules like the 1746-HSCE.
Control Relays (Motor Control Equipment) ➝
Find relays and motor control devices that can be paired with open-collector outputs from the high-speed counter for safe, reliable switching.
