GE IC687BEM742｜FIP Bus Controller｜

Product Overview
IC687BEM742 is a communication hardware specifically designed for Genius remote I/O rack expansion in GE 90-70 systems. Its core function is to connect the high-speed backplane bus link between the PLC local CPU rack and the remote expansion rack, breaking through the limitations of single rack I/O points and physical slots, and achieving the expansion of the entire control system I/O scale. It is widely used in large-scale chemical, power plant, water treatment, large-scale assembly line and other project sites in the early years.
This module is not a CPU module and does not have the ability to independently run control programs. It only undertakes the work of bus signal forwarding, data exchange, and remote rack management. It must be combined with 90-70 series CPUs, supporting racks, and dedicated expansion cables to form a complete system before it can work.
Detailed explanation of core functions
Rack bus expansion
The module is installed in the local CPU rack slot and connected to the same series expansion module paired on the remote rack through a dedicated Genius expansion cable. Under one bus link, up to 16 racks (1 main rack+15 remote slave racks) can be expanded, greatly increasing the I/O carrying capacity of the entire PLC system. The system can support up to 32768 digital signals or 8192 analog signals.
Genius Bus Protocol Processing
Running GE’s proprietary Enhanced Genius synchronous serial bus protocol, the bus communication rate can reach 2Mbps, and the communication delay between adjacent racks is low, ensuring that remote I/O data can participate in CPU scanning cycles synchronously with local rack I/O. The remote point response performance is close to that of the local board, and there will be no significant lag.
Status diagnosis and fault reporting
The module board comes with multiple sets of LED status indicator lights, corresponding to power, operation, bus communication, link faults, and other statuses. The module’s working status can be quickly judged with the naked eye on site. Once there are faults such as cable disconnection, remote rack power failure, module abnormality, etc., the fault information will be uploaded to the PLC CPU, which can be read and alarmed in programming software or upper HMI, making it convenient for operation and maintenance personnel to identify the fault point and reduce downtime.
Pure software configuration, no hardware dialing
All parameters of the module, master-slave mode, and rack address are configured through programming software. There is no DIP dip switch on the board to avoid system abnormalities caused by manual dip errors. During the debugging phase, the bus architecture planning and remote I/O point mapping can be directly completed in the software before it can be put into use.
Hardware and electrical specifications
Installation position: 90-70 series VME standard rack, occupying 1 standard slot position
Backboard power supply: Powered by the PLC rack backplane 5VDC, with a working current of approximately 1.3A, no additional external power supply is required
External interface: Genius bus dedicated expansion cable interface, used for docking with remote racks; Debug and upgrade serial port, support online firmware upgrade, no need to disassemble chip ROM
Working environment temperature: 0 ℃~+60 ℃; Storage temperature -40 ℃~+85 ℃
Humidity conditions: 5% -95% RH, non condensing environment
Supporting cable: IC687CBL series dedicated Genius expansion cable, both ends of the host rack and remote rack must be equipped with BEM742 type expansion modules for pairing use.
System compatibility
Compatible with CPU: 90-70 full series CPUs, including IC697CP771, IC697CPX928-FE, IC697CPM790 and other models of CPUs
Compatible racks: IC697RACK104, IC697RACK208, IC697RACK302, IC697RACK404 and other 90-70 racks
Backward compatibility: It can be compatible with the Genius bus architecture composed of old BEM713 modules, and old project modifications can be mixed (note firmware version matching)
Programming software: Use GE Proficy Logic Developer and early MS DOS version programming software for hardware configuration and parameter settings