Overview
The IMDSO01 is a dedicated digital output module for the ABB Bailey INFI 90® OPEN Strategic
Process Management System, designed to convert digital control commands from INFI 90 control
modules (e.g., Multi-Function Processor/IMMFP01/02, Logic Master Module/IMLMM02) into physical
switching signals for industrial field devices (e.g., relays, solenoids, contactors). As a foundational
model in the IMDSO series (alongside IMDSO02/03/14/15), it focuses on reliable 24 VDC digital
switching, with distinct differences from later models like the IMDSO14 (e.g., fixed voltage vs. dual
voltage, basic vs. enhanced EMI protection).
Physically, the IMDSO01 occupies one slot in a standard INFI 90 Module Mounting Unit (MMU) and
features a single printed circuit board (PCB) with solid-state switching circuitry. 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 1000 VDC dielectric isolation (CSA-certified) between outputs and 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 compatibility with INFI 90 termination devices (NTDI01 Termination Unit,
NIDI01 Termination Module), hot-swappable capability (install/remove without system power-off),
and compliance with industrial safety standards (CSA C22.2 No. 1010.1-92 for non-hazardous
locations, FM Class I Division 2 Groups A–D). It operates in harsh environments (0–70°C ambient
temperature, 5–95% non-condensing humidity) and communicates with control modules via the I/O
Expander Bus, using a unique 6-bit address (0–63, set via dipswitch S1) for accurate data routing.
Notably, the IMDSO01 is fixed for 24 VDC loads (unlike the dual-voltage IMDSO14) and has basic EMI
protection (vs. enhanced protection in the IMDSO14). It relies on termination devices for field wiring
connections and uses Function Code (FC) 83 in the control module configuration for signal access,
ensuring seamless integration into existing INFI 90 systems.
Core Functionality
2.1 16-Channel 24 VDC Digital Switching
The IMDSO01’s primary role is to reliably switch 24 VDC power to field devices, with key capabilities tailored to industrial control needs:
Fixed 24 VDC Output: Optimized for 24 VDC field devices, with strict electrical specifications to ensure stable operation:
Maximum sink current: 250 mA per channel (typical 150 mA), sufficient for most low-to-medium power industrial actuators.
Voltage drop: Maximum 2 V @ 70°C (minimizes power loss and device overheating).
Leakage current: Maximum 10 µA @ 70°C (prevents unintended activation of sensitive field devices).
Solid-State 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 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 24 VDC—balancing flexibility and connector efficiency for standard industrial setups.
2.2 Control Module Communication & Data Handling
The IMDSO01 operates 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 IMDSO01 via Function Code (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, ensuring command execution accuracy).
1 byte for module identification (4 MSBs) and status (1 LSB: 1 = ready, 0 = reset/fault)—confirming communication integrity and control module configuration compatibility.
Default State Management: To avoid process upsets during control module failures, the IMDSO01 supports default output states (configured via FC 128 in the control module). If communication times out (detected by a 10 ms bus fault timer), outputs automatically switch to preconfigured defaults (e.g., de-energize critical devices) or hold current states (if “hold” is enabled in FC 83 specification S2).
2.3 Front-Panel Status Monitoring & Fault Detection
The IMDSO01 includes intuitive indicators and built-in diagnostics to ensure operational reliability and simplify troubleshooting:
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 switch to defaults).
Both OFF: No power, module not seated, or critical hardware fault (check MMU backplane connection or replace module).
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 IMDSO01’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 IMDSO01 integrates seamlessly with INFI 90 termination devices and supports standardized cabling for easy deployment:
Termination Device Compatibility:
NTDI01 Termination Unit (panel-mounted, uses NKTU01/NKTU11 cables) and NIDI01 Termination Module (rack-mounted, uses NKTM01/NKTU02/NKTU12 cables). These devices provide terminal blocks for field wiring, ensuring proper 24 VDC signal polarity and isolation.
Dipshunt/jumper configurations on termination devices (e.g., NTDI01 XU1-XU16) enable customization for field-powered or system-powered loads, aligning with diverse industrial wiring practices.
I/O Expander Bus Scalability: The 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 (synchronous) communication with control modules.
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 (via control module or stop/reset button) to prevent edge connector damage. This minimizes downtime for maintenance or replacement.
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 interchangeable with IMDSO02/03 modules (same mounting, communication protocol, and FC 83 configuration) for system upgrades or replacements without reconfiguring control logic. It is also a predecessor to the IMDSO14, with the latter offering dual-voltage support (24/48 VDC) and enhanced EMI protection for more demanding applications.
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.
