ABB DO820 3BSE008514R1 Digital Output Module

The DO820 is a digital output module based on relay outputs. Its core function is to convert low-level logic signals from the control system into high-level power signals capable of directly driving field devices. The module adopts the standard S800 I/O architecture and can be seamlessly integrated with various ABB control system platforms (such as 800xA, Advant OCS, Compact Product Suite, etc.) to achieve centralized and reliable process control.

Core Product Positioning: To provide a safe, stable, and isolated discrete output solution for industrial field applications.

Key Feature Overview:

• 8 Independently Isolated Channels: Each channel features independent electrical isolation, effectively preventing inter-channel interference and field-side faults from affecting the system side, thereby enhancing system safety and reliability.

• Wide Voltage Load Driving Capability: Supports a broad voltage range of 5-250V AC/DC, with a maximum continuous load current of 3A, capable of directly driving various AC or DC loads.

• Comprehensive Diagnostics and Protection: Built-in output status indicators, supply voltage monitoring, fail-safe output preset (OSP) function, and supports reading diagnostic information via the ModuleBus.

• Flexible Installation and Configuration: Compatible with six different types of Module Termination Units (MTUs), meeting various wiring needs from compact designs to those with independent fuse protection.

• High-Reliability Design: Relay mechanical life exceeds 20 million operations, electrical life exceeds 1 million operations (at rated load), meeting long-term, high-frequency operation requirements.

  
  

2. Product Functions and Operating Principle

1. Channel Structure and Isolation

Each output channel consists of an optocoupler isolator, output status LED, relay driver, power relay, and EMC protection components. The optocoupler isolation forms the first isolation barrier, separating the internal logic circuit from the relay drive circuit. The relay contacts themselves provide complete electrical isolation between the output terminals and the module's internal circuitry. This dual-isolation design ensures high immunity to interference and system safety.

2. Diagnostics and Safety Functions

• Status Indication: Each channel has an independent LED for real-time display of the output ON/OFF state.

• Power Supply Monitoring: The module continuously monitors the 24V relay drive power from the ModuleBus. Upon loss of power, it immediately triggers an internal error signal, illuminates the "WARNING" indicator on the module, and uploads the fault information to the controller via the ModuleBus.

• Output Set as Predetermined (OSP): This is a key safety function. When the module detects a communication loss with the controller, internal fault, or power supply failure, it can automatically set all outputs to a user-predefined safe state (ON or OFF) according to a preset time (256/512/1024 ms), preventing unintended device operation and ensuring process safety.

3. Flexible Wiring Solutions

The DO820 must be used with a Module Termination Unit (MTU), which provides reliable field wiring terminals. Different MTU types can be selected based on application needs:

• TU811/TU813 (Compact): Compact structure, providing basic two-wire connection terminals.

• TU831/TU851 (Extended): Offer more wiring space and clearer terminal arrangement for easier cabling.

• TU836/TU837 (Extended with Fuses): TU836 integrates independent replaceable fuses (max. 3A) on the load output terminals of each channel, providing overcurrent protection for each load. TU837 further provides grouped process power supply input terminals (e.g., L1/N1, L2/N2), allowing the 8 channels to be divided into groups powered by different sources, enhancing power supply flexibility and safety.

  
  

3. System Integration and Compatibility

The DO820 is a core member of the ABB S800 I/O family, boasting extensive system compatibility:

• Control System Platforms: Fully compatible with major ABB control systems like 800xA (versions 5.0, 5.1, 6.0, etc.), Advant OCS (with Master and MOD 300 software), Compact Product Suite, and more.

• I/O System: Designed specifically for the S800 I/O system, it can be installed in any S800 I/O station.

• Networking and Communication: Communicates with the host communication module (e.g., CI854, CI871) of the S800 I/O station via the ModuleBus, thereby connecting to upper-level control networks (e.g., Profibus DP, Foundation Fieldbus, Ethernet).

This deep level of integration ensures the DO820 can seamlessly fit into existing ABB automation architectures, simplifying engineering design, configuration, and maintenance tasks.

4. Typical Application Scenarios

Thanks to its strong driving capability, reliable isolation, and flexible configuration, the DO820 is suitable for various industrial control applications:

1. Motor Control: Driving small AC/DC contactors to control the start/stop of pumps, fans, conveyor belts, etc.

2. Valve Control: Controlling solenoid valves or electric actuators for fluid on/off and regulation in process industries.

3. Alarm and Indication: Driving audible/visual alarms, indicator lights, buzzers, etc.

4. Heating Control: Switching power to heating elements or tapes.

5. Lighting Control: Controlling the switching of industrial lighting circuits.

6. Safety Circuits: Serving as the output unit for safety control systems (with appropriate logic), driving safety devices.

The DO820 is an ideal choice in applications requiring relays for electrical isolation, voltage conversion, or driving relatively high-power inductive/resistive loads.

5. Installation and Configuration Key Points

1. Module Installation: Insert the DO820 into an S800 I/O base unit, ensuring it is firmly seated. Select the correct MTU keying code (AD code) and install the corresponding MTU.

2. Power Connection: Ensure the ModuleBus provides stable +5V and +24V power. If using TU836/TU837, also connect the process power supply (L1/N1, L2/N2) as required.

3. Field Wiring: Connect the loads to the appropriate terminals on the MTU according to the terminal wiring diagrams (see product manual). For TU836/TU837, install fuses with the correct ratings.

4. Software Configuration: In the respective control system engineering software (e.g., Control Builder), add the DO820 module and set relevant parameters, such as OSP time, power supervision enable, safe state for each channel, etc.

5. Diagnostics and Maintenance: Monitor module status, channel output values, and diagnostic information in real-time via the software. The LEDs on the module provide intuitive local status indication.