Bus Switching Modules | GE Fanuc IC660BSM120

The IC660BSM120 is a dual-bus interface switching unit developed for the GE Fanuc Genius I/O system. Operating at 115 VAC or 125 VDC nominal supply, this module allows a cluster of up to 8 Genius I/O blocks to interface simultaneously with two redundant serial communications buses. It provides physical channel switching to ensure high system availability, maintaining bus communication link integrity in redundant control topologies.

Dual Serial Bus Switching Mechanism

The module serves as an automated relay interface between primary (Bus A) and secondary (Bus B) serial channels. When de-energized, internal switching connections default directly to Bus A. The internal switching coil energizes only when Bus B selection is mandated, switching control over to the backup line. Bus switching commands can be initiated directly via the system CPU or manually using a Genius Handheld Monitor (HHM). An integrated front-panel LED illuminates specifically when Bus B is active, offering immediate visual status to site maintenance technicians.

Power Specifications and Line Differentiation

Designed for AC/DC control environments, the module operates across a input voltage window of 90 to 130 VAC or 95 to 150 VDC. Power draw is rated at 60 mA under 115 VAC operation and 12 mA under 120 VDC conditions. System designers should note that while the IC660BSM120 shares identical functional logic and capacity with its sister model IC660BSM021, the IC660BSM021 relies on a low-voltage 24/48 VDC power input. Both units maintain a minimum contact switching reliability rating of 500,000 operations with a fast switching response time under 20 milliseconds.

Technical Specifications

Frequently Asked Questions

Q: What is the main difference between IC660BSM120 and IC660BSM021?A: Both modules offer identical dual-bus switching functions for up to 8 Genius I/O blocks, but they use different power supplies. The IC660BSM120 requires 115 VAC or 125 VDC, whereas the IC660BSM021 operates on 24/48 VDC.

Q: Which serial bus is selected by default when the module loses power?A: When de-energized, the module automatically routes connected I/O blocks to Bus A. Internal switching relays energize only when switching to Bus B is requested.

Q: How can maintenance personnel command a bus switch on this module?A: Bus switching can be triggered automatically by the host PLC CPU upon communication failure or initiated manually via a Genius Handheld Monitor (HHM).