The DI814 is a high-performance, high-reliability digital input module, part of the ABB Ability™ System 800xA® and S800 I/O series hardware. Designed for industrial automation environments, this module provides 16 channels of 24 V DC current-sourcing inputs, suitable for connecting various field devices such as switches and sensors, enabling safe and accurate transmission of field digital signals to the control system.
The core design philosophy of the DI814 centers on modularity, isolation, and diagnostic capabilities. It divides the 16 input channels into two independent, electrically isolated groups of 8 channels each, with each group featuring its own dedicated power supervision input. This groupwise isolation design significantly enhances the system's noise immunity and reliability. Even if a power failure occurs in one group, it will not affect the normal operation of the other group, effectively preventing fault propagation and ensuring continuous acquisition of critical signals.
The module integrates comprehensive diagnostic functions, including per-channel status LED indicators and group power supply voltage supervision. The status of any channel or the loss of group power can be visually indicated via the front-panel LEDs. Furthermore, detailed fault information can be read through the ModuleBus, providing powerful support for preventive maintenance and rapid troubleshooting.
Additionally, the DI814 supports a variety of Module Termination Units (MTUs), including compact and extended types, offering users flexible system configuration and field wiring solutions to meet the requirements of different application scenarios, from simple to complex.
2. Core Features and Benefits
High-Density Current-Sourcing Inputs: Provides 16 channels of 24 V DC current-sourcing inputs, delivering stable detection current directly from the module to field devices, simplifying field wiring and improving signal reliability.
Enhanced Safety and Reliability:
Groupwise Electrical Isolation: Electrical isolation is implemented between the two groups of 8 channels and between each group and system ground, effectively suppressing ground loop interference and faults caused by potential differences, enhancing system stability in harsh electrical environments.
Dual Power Supervision: Each group has an independent 24 V process power supervision input. If the external 24 V power supply for a group is lost or abnormal, the module can immediately detect and report a group error, preventing signal misjudgment due to power loss.
Excellent Noise Immunity:
Programmable Digital Filtering: Each input channel supports software-selectable digital filters (2 ms, 4 ms, 8 ms, 16 ms). This feature effectively filters out short-duration noise pulses (width less than the set time) caused by field wire induction or switching actions, ensuring only valid, longer-duration signals are read by the system, greatly enhancing immunity to electromagnetic interference (EMI).
Built-in Protection: Each channel integrates current-limiting components and EMC protection components, effectively preventing overcurrent surges and transient voltage damage.
Optical Isolation Barrier: Each channel utilizes opto-isolation to completely separate the hazardous field side from the safe control system side, protecting core control system equipment.
Comprehensive Diagnostics and Status Indication:
Per-Channel Independent LED: Each input channel has a corresponding LED that indicates the channel's logic status ("1" or "0") in real-time, facilitating quick on-site viewing.
Module Status LEDs: The front panel provides F(ault), R(un), and W(arning) indicators, giving a clear overview of the module's overall health status.
Detailed ModuleBus Diagnostics: Detailed information such as all channel errors and group power loss errors can be read by the host control system via the ModuleBus, enabling centralized and refined system monitoring.
Flexible Mounting and Connection: Compatible with various Module Termination Units (MTUs). Users can select the most suitable model based on wiring preferences, space layout, and maintenance needs, enabling convenient screw terminal, spring terminal, or D-Sub connector wiring.
Robust Industrial Design: Wide operating temperature range, high protection class (IP20), compliance with multiple international safety and electromagnetic compatibility (EMC) standards, ensuring long-term stable operation in demanding industrial environments.
3. Module Termination Unit (MTU) Selection and Connection
The DI814 module must be installed on a Module Termination Unit (MTU) for use. The MTU is responsible for the physical and electrical connection between the module and the field cables. Users can choose from the following different types of MTUs based on project requirements:
| MTU Model | Type | Key Features & Application Scenarios |
| TU830/TU833 | Extended | Recommended for standard applications. Provides spring-clamp terminals, enabling 3-wire connection (+24V, Input, 0V) without additional terminal blocks, greatly simplifying cabinet wiring and saving space and installation time. |
| TU838 | Extended | Provides screw terminals. Every two channels share a maximum 3A fuse, offering additional overcurrent protection for the output process power. Suitable for applications requiring a higher level of protection. |
| TU810/TU814 | Compact | Compact structure, cost-effective. Provides terminals for 24V process power supervision but requires external terminal blocks to distribute 24V power to field devices. Suitable for space-constrained or cost-sensitive projects. |
| TU812 | Compact | Equipped with a D-Sub 25-pin (male) connector for quick connection to field devices via prefabricated cables. Suitable for applications requiring frequent plugging/unplugging or the use of prefabricated cables, such as test benches, mobile equipment, etc. |
Connection Diagram Overview:
Using TU830/TU838 Extended MTU: Wiring is most straightforward. The +24V and 0V for each group (L1, L2) are connected directly to the designated MTU terminals (e.g., L1+, L1-). Each channel's signal wire is connected to the corresponding input terminal (e.g., C1, B1, etc.).
Using TU810/TU814 Compact MTU: An external power distribution terminal block is required in addition to the MTU. The module's power supervision inputs and channel inputs are connected directly to the MTU, while the 24V power supply for field devices is routed from the external terminal block.
Using TU812 Compact MTU: All connections are made via the 25-pin D-Sub connector. Wiring must be done according to the pin assignment table.
(For specific terminal or pin numbers for each channel, power, and supervision signal under each MTU model, please refer to the "Process Connections" table and corresponding wiring diagrams in the product manual.)
4. Typical Application Areas
Leveraging its high reliability, strong noise immunity, and flexible configuration, the DI814 is widely used in the following industrial sectors:
Process Industries: Oil & Gas, Chemicals, Pharmaceuticals, Water/Wastewater Treatment, etc., for connecting level switches, pressure switches, flow switches, valve position feedback, etc.
Manufacturing & Machine Automation: Automotive, Packaging Machinery, Machine Tools, etc., for detecting limit switches, photoelectric sensors, safety door locks, pushbutton status, etc.
Energy & Power: Power Plants, Substations, for monitoring circuit breaker status, isolator positions, alarm contacts, etc.
Marine & Shipbuilding: Certified by multiple classification societies, suitable for ship automation systems, monitoring the status of doors, pumps, fans, etc.
Infrastructure: Building Automation, Rail Transportation, for monitoring run feedback of fans, pumps, lighting, etc.
