Overview
The Digital Slave Input Module (IMDSI02) is a dedicated interface component for the Infi 90 Process
Management System, primarily designed to acquire and transmit digital process signals from
industrial field devices to the system. It supports 16 independent digital input channels, enabling the
integration of discrete field signals into the Infi 90 system for real-time processing, monitoring, and
process control.
These digital inputs—typically generated by field devices such as contact closures, mechanical
switches, or solenoids—serve as critical data sources for Infi 90 master modules (e.g., Multi-Function
Processor/IMMFP01/02, Logic Master Module/IMLMM02). In the system hierarchy, master modules
handle core control logic (e.g., loop control, sequence logic), while the IMDSI02 acts as the "I/O
bridge": it receives digital signals from the field, isolates and conditions them to ensure signal
integrity, and transmits them to master modules for use in process monitoring and control decisions.
By bridging field devices and the Infi 90 system, the IMDSI02 ensures reliable communication of
discrete state information (e.g., "device energized" or "device de-energized"), supporting essential
industrial operations like equipment status monitoring, interlock triggering, and sequence control.
Core Functionality
1. 16-Channel Digital Signal Acquisition & Integration
The IMDSI02 serves as a dedicated interface to collect 16 independent digital process field signals
(e.g., from contact closures, switches, or solenoids) and transmit them to the Infi 90 Process
Management System. It supports three common digital input voltage types: 24 VDC, 125 VDC, and
120 VAC, with each channel configurable via jumpers to match the specific voltage of the connected
field device. This enables the module to adapt to diverse industrial field scenarios, ensuring seamless
integration of discrete state signals (e.g., "device on/off") into the Infi 90 system for processing and
monitoring .
2. Signal Isolation & Conditioning for Integrity
To protect the Infi 90 system’s internal logic circuitry and ensure signal reliability, the IMDSI02
incorporates 300 V RMS isolation between input channels and between input circuits and logic
circuitry (CSA-approved). It also uses current limiters and optocouplers in the input isolation block to
separate field signals from module electronics, mitigating interference and preventing fault
propagation. Additionally, the module includes threshold detection circuits that verify if input
voltages meet "ON/OFF" criteria (e.g., minimum 21.4 VDC for 24 VDC "ON" state, maximum 12 VDC
for 24 VDC "OFF" state) to avoid false signals, ensuring accurate transmission of field device status .
3. Configurable Response Time for DC Inputs
For DC input channels (24 VDC, 125 VDC), the IMDSI02 offers selectable response times via jumpers
to address contact debounce (a common issue with mechanical field devices). Users can choose a
"fast" setting (1.5 ms response time) for time-critical applications or a "slow" setting (17 ms response
time) to filter out transient noise. This flexibility allows the module to balance responsiveness and
signal stability, adapting to different process requirements (e.g., fast-acting solenoids vs. slow
mechanical switches) .
4. Communication with Infi 90 Master Modules
The IMDSI02 acts as a slave component, communicating with Infi 90 master modules (e.g.,
IMMFP01/02, IMLMM02) via the Slave Expander Bus (a high-speed synchronous parallel bus on the
Module Mounting Unit/MMU backplane). It uses a unique address (0–63, set via dipswitch S1) to
identify itself to the master, ensuring data is routed correctly. The master module accesses the
IMDSI02’s input data and status via Function Code (FC) 84, reading two 8-bit "point data bytes"
(corresponding to 2 groups of 8 channels) that reflect each input’s "ON/OFF" state, and a "status
byte" to verify communication and configuration integrity .
5. Front-Panel Status Indication for Diagnostics
To simplify system testing and troubleshooting, the IMDSI02 features 16 front-panel LED indicators
(divided into Group A and Group B, 8 LEDs each). A lit red LED indicates an energized ("ON") input,
while an unlit LED indicates a de-energized ("OFF") input. This visual feedback allows technicians to
quickly verify field signal reception at the module level, distinguishing between field device issues
(e.g., a failed switch) and module/communication issues (e.g., no LED response despite a functional
device) .
6. Hot-Swappable & Maintenance-Friendly Design
The IMDSI02 supports hot-swapping—it can be installed or removed from the MMU without
powering down the Infi 90 system—minimizing downtime during module replacement or
maintenance. It occupies a single slot in a standard Infi 90 MMU, with captive screws on the front
panel for secure mounting. Additionally, the module’s wiring is simplified via three card-edge
connectors: P1 (logic power, +5 VDC), P2 (Slave Expander Bus communication), and P3 (digital inputs,
connected to termination units/modules like NTDI01/NIDI01 via dedicated cables), reducing 、
installation complexity .
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.
