ABB Bailey IIMLM01 Multibus Loop Module

This multibus loop module provides redundant communication capability for ABB Bailey INFI 90 systems. It manages data exchange on the multibus loop between multiple processors and I/O stations. Therefore, it ensures fault-tolerant control for critical power generation applications.

Physical and Network Specifications

The ABB Bailey IIMLM01 measures 25.0 cm in length and 18.0 cm in width. Moreover, its module weight equals approximately 0.88 kg for rack mounting. A single 48-pin male connector links this module to the INFI 90 backplane. Additionally, the unit includes two independent multibus loop interface ports.

Parameter	Specification
Brand	ABB Bailey
Full Model	IIMLM01
Category	Multibus Loop Module
Dimensions (L x W x H)	25.0 cm x 18.0 cm x 5.5 cm (9.84″ x 7.09″ x 2.17″)
Module Weight	0.88 kg (1.94 lbs)
Backplane Interface	1 x 48-pin Male Connector (INFI 90 Rack)
Power Supply Input	5 VDC from Backplane (1.2 A Typical)
Power Consumption	6.0 W (Typical)
Processor Type	16-bit Microcontroller (20 MHz)
Program Memory	128 kB ROM (Firmware)
Data Memory	64 kB RAM (Battery Backed)
Backup Battery	Internal Lithium (3V, 5 Year Life)
Loop Ports	2 x 9-pin D-Sub Female (RS-485, Isolated)
Loop Protocol	Bailey Multibus (Proprietary)
Baud Rate	1 Mbps (Fixed)
Loop Topology	Redundant Ring (Dual Cables)
Maximum Nodes per Loop	32 Devices
Maximum Cable Length per Segment	500 meters (1640 feet)
Loop Redundancy	Automatic Failover (Hot Standby)
Failover Time	< 10 ms
On-Board Components	1 Microcontroller + 4 Memory Chips + 2 UARTs + 2 Isolated Transceivers + 4 Optocouplers + 2 Isolation Transformers + 6 Protection Diodes + 1 Voltage Regulator + 1 Real-Time Clock + 1 Watchdog Timer IC
Energy Storage	3 x 220 µF Electrolytic Capacitors (35V) + 2 x 10 µF Tantalum (25V) + 1 x CR2032 Backup Battery
Battery Backup Time	5 Years (Typical for RAM and RTC Retention)
Isolation Rating	2500 Vrms (Each Loop Port to Backplane)
Operating Temperature	0°C to +55°C (32°F to 131°F)
Storage Temperature	-25°C to +85°C (-13°F to 185°F)
Mounting Type	INFI 90 Rack (Single Slot)
Status Indicators	1 Green LED (Power) + 1 Green LED (Run) + 2 Green LEDs (Loop A Active) + 2 Green LEDs (Loop B Active) + 2 Yellow LEDs (Data Activity) + 1 Red LED (Fault)

Multibus Loop Features and Redundancy

The ABB Bailey IIMLM01 manages redundant communication on the INFI 90 multibus loop. Specifically, the module operates two independent loop cables for fault tolerance. In addition, the automatic failover activates within 10 milliseconds when a cable breaks. Moreover, the 1 Mbps baud rate ensures deterministic data exchange for critical I/O. Furthermore, the module supports up to 32 nodes on each redundant loop segment. Consequently, this loop module provides uninterrupted communication for critical turbine control applications.

Isolated Loop Ports and Noise Immunity

Two fully isolated RS-485 ports provide robust loop connectivity for industrial environments. For instance, the 2500 Vrms isolation protects the backplane from electrical surges. In addition, each redundant loop cable operates independently without interference. Moreover, the isolated transceivers prevent ground loops between different rack locations. Furthermore, the proprietary Bailey multibus protocol includes error checking and retransmission. Thus, the ABB Bailey IIMLM01 performs reliably in high-voltage turbine control rooms.

Energy Storage and Data Retention

This multibus loop module stores energy using five onboard capacitors for power filtering. Specifically, three electrolytic capacitors smooth the 5 VDC supply for stable processor operation. In addition, two tantalum capacitors provide high-frequency noise suppression for loop transceivers. Moreover, a real-time clock with battery backup timestamps loop events. Furthermore, a lithium battery retains configuration parameters and loop statistics. Therefore, this module preserves loop settings for up to five years without external power.

Installation and Diagnostic Indicators

Nine LED indicators provide operational status at a glance on this module. First, a green Power LED lights when the 5 VDC backplane supply is present. Second, a green Run LED flashes during normal firmware execution. Third, two green Loop A Active LEDs illuminate when each redundant loop cable is operational. Fourth, two green Loop B Active LEDs show secondary loop status. Fifth, two yellow Data Activity LEDs flash during data transmission or reception. Finally, a red Fault LED indicates hardware errors, loop breaks, or node failures. Additionally, the module includes a locking ejector for secure backplane insertion. Thus, you can diagnose multibus loop status instantly without external tools