Product Overview
The 1746sc-CTR4 is a 4-channel high-speed counter / flowmeter input module manufactured by Spectrum Controls, Inc., an Encompass partner of Rockwell Automation, and is designed specifically for the widely deployed Allen-Bradley SLC 500 programmable controller platform. As a member of the Spectrum Controls SLC 500 Specialty I/O family, the 1746sc-CTR4 captures fast pulse trains from incremental encoders, turbine flowmeters, magnetic pickups, and discrete sensing devices, then converts those signals into binary count and rate values that the SLC processor reads directly over the backplane.
The module provides four differential counter inputs, supports up to two channels of quadrature encoding for directional position tracking, and offers dedicated external enable control lines that gate counter execution in hardware — all within a single SLC 500 chassis slot. Inputs accept a broad range of signal formats, including AC 50 mV to 75 V peak as well as 5 V, 12 V, and 24 V DC sources, and counting rates up to 50 kHz on both AC and DC channels. Built-in K, M, and R scaling factors allow direct conversion of turbine-meter pulse frequencies into engineering units such as gallons, liters, or pounds without additional ladder programming.
Fully compatible with both fixed-hardware and modular-style SLC 500 chassis and with every SLC 500 processor from the 5/01 through the Ethernet-capable 5/05, the 1746sc-CTR4 integrates transparently into existing control schemes and can be deployed in local, remote (via 1747-ASB), or distributed I/O configurations. Front-panel status LEDs — one module indicator plus four individual input indicators — provide immediate visual feedback for commissioning and troubleshooting.
As legacy SLC 500 systems continue to operate reliably across thousands of process plants, batching facilities, and packaging lines worldwide, the 1746sc-CTR4 remains a critical spare-part item for maintenance teams, restoring failed counting and flow-measurement channels in minutes while preserving the substantial investment in proven Allen-Bradley SLC 500 control infrastructure.
Technical Specifications
| Parameter Name | Parameter Value |
|---|---|
| Product Model | 1746sc-CTR4 |
| Manufacturer | Spectrum Controls (Encompass Partner of Rockwell Automation) |
| Product Type | 4-Channel Counter / Flowmeter Input Module |
| Series / Platform | Allen-Bradley SLC 500 Specialty I/O |
| Number of Inputs | 4 differential counter inputs; 2 quadrature encoding channels; 2 enable control lines |
| Input Voltage Range | AC 50 mV to 75 V peak; 5 V DC, 12 V DC, 24 V DC |
| Input Frequency | 50 kHz maximum (AC and DC); 1 Hz to 50 kHz rate mode |
| Minimum Pulse Time | 8 µs (DC mode); enable/disable setup 20 µs |
| Input Impedance | 25 kΩ |
| Input Filters | Digital 50 kHz (default) / 30 kHz; Analog 15 kHz |
| Channel Update Time | 4.0 ms (OFF transition); 5.6 ms (ON transition) |
| Count Range | Low Range ±32,767; High Range ±8,388,607 |
| Count Accuracy | ±1 count; rate accuracy ±1% @ 50 kHz, 0.001% @ 1 Hz |
| Backplane Current (Max) | 225 mA @ 5V DC |
| Power Dissipation | 1.75 W maximum |
| Status Indicators | Module status LED plus 4 individual input LEDs |
| Termination | 24-pin removable connector; accepts one 12–28 AWG wire per terminal |
| Module Width | Single SLC 500 chassis slot |
| Compatible Hardware | SLC 500 fixed and modular style systems |
| Certifications | UL Listed, CE |
| Weight | 0.38 lbs (0.17 kg) |
| Country of Origin | Made in U.S.A. |
