ABB AO845 3BSE023676R1 – S800 I/O Analog Output Module for 4–20 mA Field Control

The ABB AO845 (order code 3BSE023676R1) is an analog output module in the S800 I/O family, typically used with AC 800M/800xA systems to drive control valves, dampers, VFD reference inputs, dosing pumps, and other current-driven actuators. From my experience, it’s a solid pick when you need stable 4–20 mA outputs with tight loop performance and neat integration into existing S800 I/O backplanes. You might notice that it’s often chosen as a drop-in replacement in brownfield upgrades because wiring and diagnostics stay familiar for maintenance teams.

Company’s Order Placement Process and Guarantees

• Warranty: 365 days
• Delivery: 1 week for in-stock items; no more than one month at the latest
• Payment: 50% advance payment, full payment before delivery
• Express options: FedEx, UPS, DHL

Key Features

• Analog current outputs (4–20 mA) – Suited for valve positioners, drive references, and process actuators where dependable loop control matters.
• Multi-channel density – Provides a practical number of channels for compact panels, typically minimizing cabinet footprint and I/O cost per point.
• S800 I/O backplane integration – Plugs onto TU8xx termination units on DIN rail; wiring stays clean and service-friendly.
• Engineering consistency in 800xA – Parameterization and diagnostics align with the S800 toolset, which usually shortens commissioning time.
• Robust loop driving capability – Designed to source current into common field loads; in many cases supports up to around 600 Ω loop resistance.
• Status and diagnostics – Channel and module status reporting helps pinpoint wiring faults or loop breaks faster.

Technical Specifications

Note: Exact limits (channels, loading, isolation) can differ by AO845 sub-variant and termination unit. If you need a precise match to an existing loop design, share your TU model and system revision and we’ll verify against the ABB datasheet.

Application Fields

• Oil & Gas and petrochemical units driving valve positioners (4–20 mA with position feedback on separate AI)
• Water & Wastewater dosing skids and aeration control, where stable current outputs keep PID loops calm
• Power and utilities: boiler draft control, feedwater control, and damper actuation
• Food & Beverage batching: analog references to VFDs and metering pumps
• Pharma and fine chemicals: precise analog control for reactors and environmental systems

A maintenance lead at a water treatment plant told us they swapped in AO845 units during a weekend outage and had loops tuned by Monday—no surprises in the wiring, which is usually the biggest time sink.

Advantages & Value

• Reliability – S800 I/O modules have a strong track record in continuous process environments.
• Compatibility – Works within ABB 800xA/AC 800M architectures; engineering and diagnostics are consistent across the family.
• Cost Control – High channel density typically reduces cabinet space, I/O baseplates, and wiring accessories.
• Serviceability – Module replacement is straightforward; you keep existing TU wiring intact in most cases.
• Technical Support – We can help check TU matching, channel allocation, and loop loading prior to shipment to avoid rework onsite.

Installation & Maintenance

• Cabinet environment – Mount on DIN rail inside an enclosure meeting typical industrial standards (e.g., IP54+). Keep ambient 0…55 °C with adequate ventilation.
• Wiring practices – Use shielded twisted pair for analog loops; ground shields at one end only to minimize noise. Verify loop polarity before powering.
• Load checks – Confirm total loop resistance is within the AO845’s drive capability (often up to ~600 Ω).
• Safety – De-energize the ModuleBus and isolate field power before inserting/removing modules. Observe ESD handling.
• Routine maintenance – Periodically function-test outputs with a calibrated meter, clean dust from ventilation paths, and review 800xA diagnostics. Keep controller/system firmware current for best stability.

Quality & Certifications

• CE compliant
• UL/cUL recognized (typical for S800 I/O modules)
• RoHS compliant
• Manufacturer’s standard warranty practices apply; our supply warranty is 365 days

Quick tip: If you’re matching an existing cabinet, share the termination unit (e.g., TU8xx) and channel count you’re using. We’ll validate the AO845 3BSE023676R1 fit and loop limits so commissioning stays smooth.