Overview
The IMDSO14 is a dedicated digital output module for the ABB Bailey INFI 90® OPEN Strategic
Process Management System, designed to transmit discrete control signals from the INFI 90 system
to industrial field devices (e.g., solenoid valves, relays, contactors). As a distinct model in the IMDSO
series (differentiated from IMDSO01/02/03/04/15), it offers unique advantages: dual voltage
compatibility (24 VDC/48 VDC), enhanced EMI protection, and direct replaceability for legacy
IMDSO04 modules—making it a versatile solution for upgrading or expanding INFI 90 systems.
Physically, the IMDSO14 occupies one slot in a standard INFI 90 Module Mounting Unit (MMU) and
features a single printed circuit board (PCB) with solid-state switching circuits. It provides 16
independent output channels: 12 fully isolated channels, plus 2 pairs of channels (Channels 7–8 in
Group A/B) that share common positive (+) terminals (optimizing connector pin usage while
maintaining isolation from module logic). The front panel includes 2 module status LEDs (red/green)
for operational feedback and 16 output status LEDs (red) to visualize each channel’s ON/OFF state—
simplifying on-site testing and troubleshooting.
Key design features include 1000 VDC dielectric isolation (CSA-certified) between outputs and logic
circuits, hot-swappable capability (install/remove without system power-off), and compliance with IEC
61000-4 series EMC standards for industrial robustness. It operates in harsh environments (0–70°C
ambient temperature, 5–95% non-condensing humidity) and communicates with INFI 90 control
modules (e.g., Multi-Function Processor/IMMFP01/02, Logic Master Module/IMLMM02) via the I/O
Expander Bus, using a unique 6-bit address (0–63, set via dipswitch S1) for data routing accuracy.
The module relies on termination devices (NTDI01/NTDO02 Termination Units, NIDI01 Termination
Module) for field wiring connections and uses Function Code (FC) 83 in the control module
configuration for signal access. It also includes fault-tolerant features like default output states
(configured via FC 128) to maintain process stability if communication with the control module fails.
Core Functionality
2.1 Dual-Voltage 16-Channel Digital Signal Output
The IMDSO14’s primary role is to convert digital control commands from INFI 90 control modules into physical switching signals for field devices, with key capabilities:
Dual Voltage Support: Optimized for 24 VDC and 48 VDC loads, with tailored current ratings to match industrial device requirements:
24 VDC: Maximum current 250 mA per channel (typical 150 mA), ideal for most low-power solenoids and indicators.
48 VDC: Maximum current 125 mA per channel (typical 75 mA), suitable for higher-voltage industrial actuators.
Voltage drop: Maximum 2 V @ 70°C (minimizes power loss); leakage current: Maximum 10 µA @ 70°C (prevents false device activation).
Solid-State Switching & Isolation: Uses open-collector transistors paired with optocouplers for output switching, providing 1000 VDC dielectric isolation between channels and between outputs and logic circuits. This design prevents fault propagation (e.g., field short-circuits affecting the INFI 90 system) and meets CSA C22.2 No. 1010.1-92 safety standards.
Channel Grouping: 16 outputs are divided into two groups (A/B, 8 channels each). Twelve channels are fully independent; the remaining two pairs (Channels 7–8) share common positive terminals (Table 5-4) and must use the same voltage configuration—balancing flexibility and connector efficiency.
2.2 Control Module Communication & Data Handling
The IMDSO14 acts as a slave device on the INFI 90 I/O Expander Bus (12-line synchronous parallel bus), enabling bidirectional data exchange with control modules:
Address & Function Code Integration: A unique 6-bit address (set via 8-position dipswitch S1; Positions 3–8 for address, Positions 1–2 = closed) links the module to the control module. Control modules access the IMDSO14 via FC 83 (specification S1 = module address), sending two 8-bit “output data bytes” (one per group) to set channel states (Logic 1 = ON, Logic 0 = OFF).
Status Feedback: The module transmits three 8-bit “status bytes” to the control module:
2 bytes for output readback (verifying actual ON/OFF states of Group A/B channels).
1 byte for module identification (4 MSBs) and status (1 LSB: 1 = ready, 0 = reset/fault)—ensuring communication integrity and configuration compatibility.
Default State Management: To avoid process upsets during control module failures, the IMDSO14 stores default output values (configured via FC 128) in a dedicated register. If communication times out (detected by a 10 ms bus fault timer), the module automatically switches to default states (e.g., de-energize critical outputs) or holds current states (if “hold” is enabled in FC 83 specification S2).
2.3 Front-Panel Status Monitoring & Fault Detection
The IMDSO14 includes intuitive indicators and built-in diagnostics to simplify system maintenance:
Module Status LEDs:
Green ON, Red OFF: Normal operation (enabled and communicating with the control module).
Red ON, Green OFF: Bus fault (control module communication lost, outputs switched to default states).
Both OFF: No power or module not enabled (check address matching or bus connection).
Output Status LEDs: 16 red LEDs (Group A/B, 8 each)—lit = channel energized (ON), unlit = de-energized (OFF). This visual feedback allows technicians to quickly verify signal transmission to field devices (e.g., distinguishing between a module error and a faulty actuator).
Control Module Error Reporting: If the IMDSO14’s address (S1) does not match FC 83 specification S1, or if the I/O Expander Bus dipshunt is missing, the control module generates a “MISSING SLAVE MODULE” error. FC 83 output block N (Logic 0 = good, Logic 1 = bad) provides a digital status flag for remote monitoring via INFI 90 operator interfaces (OIS, EWS, CTT).
2.4 Termination & System Integration
The IMDSO14 integrates seamlessly with INFI 90 termination devices and supports flexible cabling configurations:
Termination Device Compatibility:
NTDI01/NTDO02 Termination Units (for panel mounting, use NKTU01/11/NKDO01/11 cables).
NIDI01 Termination Module (for rack mounting, use NKTM01/NKTU02/12 cables).
Dipshunt/jumper configurations on termination devices (e.g., NTDO02 XU01–XU10) enable advanced applications (e.g., one module output controlling multiple relays).
Bus Scalability: The I/O Expander Bus can be extended to 6 MMUs via cables, supporting large-scale system configurations. A custom gate array in the module handles address detection, function code decoding, and data filtering—ensuring high-speed, noise-free communication.
2.5 Hot-Swappable & Low-Maintenance Design
Hot-Swapping: The module can be installed or removed while the INFI 90 system is powered on, but requires disabling output signals first (to prevent edge connector damage). This minimizes downtime for replacement or maintenance.
Preventive Maintenance: Requires only periodic cleaning (static-safe vacuum for PCB/MMU dust removal) and tightening of power/ground connections (every 6 months or plant shutdown). No on-board fuses or calibration are needed, reducing lifecycle costs.
Legacy Compatibility: Directly replaces IMDSO04 modules (with identical mounting and communication protocols) while adding 48 VDC support and enhanced EMI protection—simplifying system upgrades without reconfiguring control logic.
ABB Bailey INFI 90 Series: System Structure & Key Components
The ABB Bailey INFI 90 series is a modular distributed process control system (DCS) tailored for
industrial automation and safety-critical scenarios, featuring a hierarchical architecture that connects
field equipment, slave modules, master controllers, and operator interfaces. At its core, the system
relies on master-slave communication to enable process monitoring and control: the Multi-Function
Processor (MFP: IMMFP01/02) and Network 90 Multi-Function Controllers serve as central master
units, while the IMASI02 (Analog Slave Input Module) acts as a dedicated slave component that
inputs 15 channels of analog signals from field devices (e.g., sensors, Bailey smart transmitters) to the
master controllers. Critical supporting components include termination devices (NTAI05 Termination
Unit, NIAI04 Termination Module) that configure and route field signals to the IMASI02 via specialized
cables (NKTU01, NKTM01), and the Slave Expander Bus (a backplane-mounted parallel bus in the
Module Mounting Unit/MMU) that enables real-time data exchange between the IMASI02 and MFP.
Operator interfaces like the Operator Interface Station (OIS), Configuration and Tuning Terminal (CTT),
and Smart Transmitter Terminal (STT) further integrate with the system—allowing users to configure
the MFP (via FC 132/133), send commands to smart transmitters through the IMASI02, and monitor
process status, while the Controlway and INFI-NET/Plant Loop provide redundant, plant-wide
communication for seamless scalability.
