When Pulse Counting Stalls Production
A packaging line jams because the PLC misses high-speed encoder pulses. A cut-to-length application drifts out of tolerance. These are the failure modes that cost throughput and scrap material. The Allen-Bradley 1746-HSCE2 high-speed counter module solves them by offloading fast pulse counting from the SLC 500 processor. It is a single-slot module for the SLC 500 series that counts in both directions, handles quadrature signals, and delivers real outputs for immediate control actions.
What Is the 1746-HSCE2?
The 1746-HSCE2 is a multi-channel high-speed counter module from Allen-Bradley. It accepts inputs ±A1, ±B1, ±Z1, ±A2, ±B2, and ±Z2. The module provides eight outputs: four virtual and four real. It supports up to four pulse counters or two quadrature counters. Each counter counts to ±8,388,607 in linear or ring mode. A dedicated processor handles signal processing, so the SLC 500 CPU stays free for logic and communication tasks.
Technical Specifications That Matter
Input Flexibility
The module accepts 4.2 V dc to 12 V dc and 10 V dc to 30 V dc input ranges. Nominal voltages are 5 V dc and 24 V dc. This dual-range design lets you connect 5 V encoders and 24 V sensors on the same module without external conditioning.
Speed and Resolution
Minimum pulse width is 475 ns. Minimum phase separation is 200 ns. Maximum input frequency reaches 1 MHz. These figures support high-resolution encoders and fast counting in flying-shear, registration, and length-measurement applications.
Outputs and Isolation
Eight outputs are available: four virtual and four real. Output voltage range is 10-30 V dc. Maximum on-state current per channel is 1.0 A, with 2.0 A per module at 40°C and 1.5 A at 60°C. Backplane isolation is 1000 V, and channel-to-output isolation is 500 V. Thermal cut-out protection turns off all channels within milliseconds if overload occurs.
Backplane and Update Time
Backplane current at 5 V is 250 mA. Update time is 1.5 ms. Step response is 100 ms in and 2.5 ms out. These values help you plan scan-time budgets and control-loop response.
Where the 1746-HSCE2 Fits
Packaging and Labeling
High-speed registration marks and encoder feedback demand fast counting. The 1 MHz input frequency and 475 ns pulse width handle these signals without missing counts.
Cut-to-Length and Web Handling
Quadrature inputs track material length and direction. The Z input resets the counter at each cycle, preventing cumulative error. This reduces scrap and improves product consistency.
Motion and Position Monitoring
With 24-bit resolution, the module monitors position over long travel distances. The four real outputs trigger diverters, brakes, or alarms at preset positions.
Replacing an Existing Counter Module
If you are upgrading from an older SLC 500 counter module, the 1746-HSCE2 offers a direct replacement path. Verify your existing I/O connection and backplane current budget. The module uses one slot and draws 250 mA at 5 V. It works with all SLC 500 CPU modules and with the 1747-ASB remote I/O adapter as a RIO component.
Installation and Wiring Notes
Mount the module in any single SLC 500 slot. Connect inputs using the specified I/O connection. Keep input cables away from noise sources, especially when using low-frequency signals. The module may accept false pulses from noise; route cables to lead current away from noise. Follow the manufacturer’s wiring diagram for the 1746-RT25G connection.
Maintenance and Reliability
Inspect connections periodically for tightness and corrosion. Verify that the thermal cut-out has not tripped after an overload event. Keep the enclosure free of dust and moisture. The module has no moving parts, so wear is minimal. Replace only if diagnostics indicate a failure.
Compatibility and Integration
The 1746-HSCE2 works with all SLC 500 CPU modules. It also functions as a remote I/O component with the 1747-ASB adapter. This flexibility lets you place the counter near the process and reduce wiring runs.
Selection Checklist
Before ordering, confirm your input signal type (single-ended or differential), voltage range, and required output count. Verify that your SLC 500 chassis has an open slot and sufficient backplane current. If you need a replacement or spare, SpareTechPLC stocks this module and can confirm availability. Please verify current lifecycle status and availability with SpareTechPLC before ordering.
Frequently Asked Questions
What is the maximum input frequency of the 1746-HSCE2?
The maximum input frequency is 1 MHz.
How many real outputs does the 1746-HSCE2 provide?
It provides four real outputs and four virtual outputs.
Can the 1746-HSCE2 count in both directions?
Yes, it can be configured to count in both directions.
What is the backplane current draw at 5 V?
The backplane current at 5 V is 250 mA.
Does the 1746-HSCE2 work with all SLC 500 CPUs?
Yes, it is compatible with all SLC 500 CPU modules.
