Allen-Bradley 1746-NO4I – 4-Point Current-Sourcing Analog Output Module | SLC 500 Platform
Engineering Background
The Allen-Bradley 1746-NO4I is a current-sourcing analog output module designed for the SLC 500 modular I/O platform. Engineered by Rockwell Automation, this module addresses the demanding signal integrity requirements of industrial process control, where precise 4–20 mA loop-powered outputs are essential for driving control valves, variable-frequency drives, and proportional actuators. Its architecture eliminates the need for external signal conditioners in most standard loop configurations, reducing panel complexity and wiring overhead.
Product Positioning
The 1746-NO4I occupies the mid-density analog output tier within the SLC 500 ecosystem, offering four independently configurable current-sourcing channels in a single slot. It is the preferred choice for process engineers who require deterministic analog output performance within an existing SLC 5/03, 5/04, or 5/05 control architecture, without migrating to the ControlLogix platform. Konmask supplies this module as genuine Rockwell Automation hardware, sourced through verified industrial channels, with full traceability documentation available upon request.
Complete Technical Specifications
| Parameter | Specification |
|---|---|
| Catalog Number | 1746-NO4I |
| Platform | SLC 500 Modular I/O |
| Number of Output Channels | 4 (independently configurable) |
| Output Signal Type | Current-sourcing (4–20 mA) |
| Output Range | 4–20 mA DC |
| Resolution | 12-bit (0–4095 counts) |
| Accuracy | ±0.5% of full scale at 25°C |
| Maximum Load Resistance | 750 Ω at 20 mA |
| Output Isolation | Channel-to-backplane isolated |
| Backplane Current Draw (5V DC) | 150 mA |
| Backplane Current Draw (24V DC) | 0 mA |
| External Power Supply | Not required (backplane powered) |
| Operating Temperature | 0°C to +60°C (32°F to 140°F) |
| Storage Temperature | -40°C to +85°C |
| Relative Humidity | 5–95% non-condensing |
| Vibration | 2g @ 10–500 Hz |
| Shock | 30g operational |
| Enclosure Rating | Open-type (requires enclosure) |
| Certifications | UL Listed, CE Marked, CSA Certified |
| Module Slot Width | Single-slot SLC 500 chassis |
| Weight | Approx. 200 g |
| Compatible Processors | SLC 5/01, 5/02, 5/03, 5/04, 5/05 |
Proven Application Environments
- Process Control: Valve positioner control in oil & gas, chemical, and water treatment plants using 4–20 mA loop signals.
- Drive Speed Reference: Analog speed setpoint output to ABB, Siemens, and Danfoss VFDs in conveyor and pump systems.
- Batch Manufacturing: Proportional ingredient dosing in food & beverage and pharmaceutical production lines.
- HVAC Automation: Damper actuator and chiller capacity control in building management systems integrated with SLC 500 PLCs.
- Power Generation: Turbine governor and excitation control auxiliary output in legacy power plant DCS/PLC hybrid architectures.
- Material Handling: Tension control and web guide positioning in printing and converting machinery.
Engineering Advantages
- True Current-Sourcing Architecture: Eliminates the need for external loop power supplies in standard 2-wire transmitter configurations, simplifying panel design.
- 12-Bit Resolution: Provides 4096 discrete output steps across the 4–20 mA range, delivering sub-0.004 mA step resolution for fine process control.
- Channel-to-Backplane Isolation: Protects the SLC 500 backplane and processor from field-side ground loops and transient surges.
- Single-Slot Form Factor: Maximizes chassis density in space-constrained panels; compatible with all SLC 500 fixed and modular chassis configurations.
- Deterministic Update Rate: Output values are updated every RPI (Requested Packet Interval) scan cycle, ensuring predictable loop response times.
- RSLogix 500 Native Integration: Full tag-based programming support with I/O image table mapping; no custom function blocks required.
System Architecture & Signal Flow
The 1746-NO4I occupies a single slot in any SLC 500 modular chassis (1746-A4 through 1746-A13). The SLC processor writes 16-bit integer output words to the module’s output image table (O:x.0 through O:x.3 for channels 0–3). The module’s onboard DAC converts these digital values to proportional 4–20 mA current signals sourced from the backplane 5V DC supply. Each channel drives an independent current loop; field wiring connects to the removable terminal block (RTB) on the module face. Loop return wires connect to the common terminal. No external 24V DC field power is required for standard current-loop loads up to 750 Ω.
Wiring Summary: Channel output (+) → Field device (+) → Field device (–) → Module common (–). Shielded twisted-pair cable is recommended for runs exceeding 10 meters to minimize EMI-induced noise on the 4–20 mA signal.
Sourcing & Quality Verification
- Genuine Hardware: All 1746-NO4I units supplied by Konmask are sourced from verified industrial distributors and authorized surplus channels. Counterfeit or refurbished-as-new units are not accepted.
- Functional Testing: Each module undergoes bench-level power-on verification prior to shipment. Full loop calibration testing is available upon request.
- Traceability: Date codes, serial numbers, and sourcing documentation are retained and available for regulated industries (pharmaceutical, nuclear auxiliary, defense).
- Packaging: Shipped in anti-static ESD bags with foam cushioning. Original Rockwell Automation packaging preserved where available.
- Warranty: 90-day Konmask operational warranty covering DOA and early-life failure. Extended warranty options available for volume orders.
Procurement Process
- Confirm Compatibility: Verify your SLC 500 chassis model and processor firmware version support the 1746-NO4I (all SLC 5/01–5/05 processors are compatible).
- Request a Quote: Contact Konmask via email at support@konmask.com or call +0086 19859288691 with your required quantity and delivery timeline.
- Order Confirmation: Receive a formal quotation with unit price, lead time, and shipping options (DHL Express, FedEx International, or sea freight for bulk orders).
- Payment & Dispatch: Payment via T/T bank transfer or agreed terms. Modules are dispatched within 1–3 business days of payment confirmation.
- Documentation Package: Shipping invoice, packing list, and sourcing certificate provided with every order. CE/UL declarations available on request.
Technical FAQ
Q: Can the 1746-NO4I output voltage signals (±10V DC)?
A: No. The 1746-NO4I is a current-sourcing-only module (4–20 mA). For voltage output requirements, specify the 1746-NO4V (±10V DC voltage output variant).
Q: Is the module compatible with ControlLogix or CompactLogix chassis?
A: No. The 1746-NO4I is exclusively designed for the SLC 500 modular chassis backplane. For ControlLogix, the equivalent module is the 1756-OF4 or 1756-OF8.
Q: What is the maximum cable length for the analog output loops?
A: Rockwell Automation recommends a maximum of 300 meters (1000 ft) for shielded twisted-pair wiring, provided total loop resistance does not exceed 750 Ω at 20 mA.
Q: Does the module support HART protocol?
A: No. The 1746-NO4I does not support HART communication. It provides a standard 4–20 mA analog signal only.
Q: Can I hot-swap the module while the SLC system is powered?
A: Hot-swapping is not supported on the SLC 500 platform. The chassis must be powered down before inserting or removing any I/O module to prevent damage to the backplane or module.
Q: What RSLogix 500 version is required for configuration?
A: RSLogix 500 version 7.0 or later is recommended. The module is configured via the I/O configuration tree; no additional EDS file is required.
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