ABB AO820 Analog Output Module (3BSE008546R1)

The ABB AO820 (article number 3BSE008546R1) is an 8-channel analog output module for the AC800M programmable logic controller platform. This module provides 8 independent current outputs, each configurable for 4-20 mA signals. It features 12-bit resolution and galvanic isolation between channels and the backplane. The AO820 is designed for precise control of actuators such as valve positioners, variable speed drives, and chart recorders in process automation. The module supports HART communication protocol (with optional hardware) for two-way digital communication with smart field devices. It is part of ABB’s S800 I/O family, known for high reliability and industrial ruggedness.

Technical Specifications

Number of output channels: 8. Output signal: 0-20 mA or 4-20 mA (software selectable). Load range: 0-750 Ω. Resolution: 12 bits (approximately 4.9 µA per bit). Accuracy: ±0.1% of full scale at 25°C, ±0.2% over temperature range. Update time: 10 ms for all channels (typical). Galvanic isolation: 500 V between channels and backplane. Power supply: 24 V DC (20.4-28.8 V) from backplane, consumption 50 mA plus loop power. Dimensions: 112 mm (H) × 45 mm (W) × 115 mm (D). Weight: 0.2 kg. Operating temperature: -40°C to +70°C (extended range). Storage: -40°C to +85°C. Humidity: 5-95% non-condensing. Protection rating: IP20. The module includes LED indicators for power and communication status. Certifications: CE, UL, ATEX, IECEx, RoHS.

Key Features

• 8 isolated analog output channels, 4-20 mA or 0-20 mA

• 12-bit resolution for precise actuator control

• Galvanic isolation between channels and backplane

• HART protocol support (requires external HART modem)

• Wide operating temperature range (-40°C to +70°C)

• Redundant I/O capability (optional)

• Hot-swappable in S800 I/O racks

• LED status indicators per channel

Integration with AC800M

The AO820 is installed in an S800 I/O rack and communicates with the AC800M CPU via the ModuleBus. The module’s output data is mapped directly to the CPU’s memory. Configuration is performed using ABB’s Control Builder M software. Each channel can be individually configured for range (4-20 mA or 0-20 mA), fail-safe value, and ramp rate. The module also supports signal monitoring and diagnostics (open loop detection).

Applications

The AO820 is used in process industries such as oil & gas, chemical, power generation, and water treatment. Typical applications include controlling I/P converters for pneumatic valves, speed reference for VFDs, and setpoint for chart recorders. The HART capability allows remote diagnostics and configuration of smart field devices.

Installation and Wiring

Mount the module in an S800 I/O rack (e.g., TU810, TU830). Connect the 24 V DC field power to the termination unit. For each channel, connect the positive output to the actuator’s + terminal and the negative to the common return (internal). Use shielded twisted-pair cables; ground the shield at the termination unit. The module is hot-swappable: it can be replaced without powering down the rack. After installation, download the configuration from Control Builder M.

Maintenance and Diagnostics

The module has LEDs: green (RUN) indicates normal operation, red (ERR) indicates a fault. If the red LED is on, check the ModuleBus connection and field power. The module diagnostics can be read via Control Builder M. No routine calibration is required; the module is factory-calibrated. Periodic cleaning of the module and rack is recommended.

Conclusion

The ABB AO820 analog output module provides reliable, high-precision control for up to 8 analog actuators. Its robust design, HART readiness, and wide temperature range make it a suitable choice for demanding process automation applications within the AC800M ecosystem.