Application Scenarios
A municipal wastewater treatment plant in the U.S. Northeast operated four return-activated-sludge pumps, three chemical-dosing metering pumps, and a chlorine-residual trim valve — all driven by analog references sourced from a single SLC 5/04 panel. The original panel relied on stacked 2-channel and 4-channel analog output modules, each with its own loop-power supply, external isolator, and set of calibration trimmers that had drifted with enclosure temperature swings. When the plant upgraded to the 1746-NO8V/A, all eight analog references consolidated onto a single software-configurable card, the per-loop isolator count dropped to zero, and seasonal calibration visits were eliminated because accuracy was maintained at 0.1% of full scale across the entire operating envelope.
The 1746-NO8V/A addresses three recurring pain points in SLC 500 analog control: the slot-count pressure created by low-density analog output cards that force multi-chassis expansion, the calibration drift of trimmer-based analog output cards installed in thermally cycling enclosures, and the wiring complexity that multi-card analog panels introduce at commissioning and every subsequent modification. Wherever an SLC 500 processor must drive voltage-referenced actuators in quantity — VFD speed references, I/P converter setpoints, valve positioners, damper actuators, recorder inputs — the 1746-NO8V/A provides the dense, software-configurable output backbone.rockwellautomation.com+1
Parameter
| Main Parameters | Value/Description |
|---|---|
| Product Model | 1746-NO8V/A (Series A revision of the 1746-NO8V) |
| Manufacturer | Rockwell Automation / Allen-Bradley (SLC 500 family) |
| Product Category | 8-Channel Analog Voltage Output Module |
| Output Channels | 8 individually configurable voltage outputs, one DAC per channel |
| Output Range | ±10.25 V DC bipolar; software-selectable unipolar and bipolar ranges |
| Resolution | 16-bit, 320 µV/count — high-fidelity signal reproduction for smooth actuator response |
| Output Coding | -32,768 to +32,767 (two’s complement integer) from the SLC data file |
| Accuracy | 0.1% of full scale at 25°C; 0.2% at 60°C — verified across the enclosure thermal range |
| DAC Architecture | Built-in R-2R ladder network per channel — no external converter required |
| Update Time | 540 µs for all 8 channels (≈1 ms full refresh) — fast enough for closed-loop analog control |
| Per-Channel Load | 10 mA per output channel — direct drive of VFD references and I/P converters |
| Backplane Current | 7 mA @ 5 V DC; 135 mA @ 24 V DC — modest draw against the SLC 500 chassis budget |
| External Power | User-supplied 24 V DC, 5.6 W maximum — isolated from backplane logic |
| Configuration | Fully software-configurable via the SLC processor — no DIP switches, no trimmers, no field calibration |
| Approximate Weight | 0.99 lb (~0.45 kg) |
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